Glossary

Term Acronym Definition Source
Aggregate Price Node APNode A collection of Price Nodes (PNodes) whose prices are averaged with a defined weighting component to determine an aggregate price. IMP Glossary
Aggregating Entity AE The entity responsible for end-use meter reading aggregation and application of transmission and distribution losses from tariff filings. Glossary Page
Ancillary Service Plan AS Plan The AS Plan (also referred to as the AS Capacity Plan) is submitted by each Transmission Customer (TC) to enable the SPP Market Operations System (MOS) to confirm each TC is satisfying its ancillary service requirements. The AS Plan indicates transfers of obligations between TCs and, when self-arranged, which resources are providing these services. Glossary Page
Ancillary Services AS Generally refers to the services necessary to support the transmission of capacity and energy from resources to loads while maintaining reliable operation of the transmission system. The Integrated Marketplace will set prices for certain ancillary services such as Operating Reserves, as part of both the Day-Ahead Market and the Real-Time Balancing Market. IMP Glossary SPP Tariff
Approved Scheduling Entity ASE Entity responsible for submission of schedules on behalf of transmission users Glossary Page
Area Control Error   ACE A Control Area's (CA's) error in meeting its obligation to match load and generation and support the interconnection frequency. It’s the number of minutes from the last time a CA (aka Balancing Authority) crossed zero. Glossary Page
Area Interchange Error   AIE Calculated as the amount of Inadvertent that is caused by the Control Area outside its obligations to the interconnection. Glossary Page
Asset Owner AO An owner of any combination of: (1) registered physical assets (Resource, Load, Import Interchange Transaction, Export Interchange Transaction, Through Interchange Transaction); (2) Transmission Congestion Rights (TCRs); or (3) any combination of financial assets (Virtual Energy Offer, Virtual Energy Bid, Bilateral Settlement Schedules) within the SPP Balancing Authority Area. IMP Glossary
Assets Can include individual units (generators), plants, loads acting as a resource (controllable load and demand response resource) and load zones. Transmission Customers (TCs) can aggregate units into plants if the units are co-located (in relation to their injection points into the grid) and electrically equivalent (meaning they are injecting at the same voltage). A TC should have their units registered with SPP. Glossary Page
Auction Clearing Price ACP The prices generated at each source and sink Settlement Location in each round of the Annual Transmission Congestion Rights (TCR) Auction and Monthly TCR Auction based upon the TCR offers and bids submitted. IMP Glossary
Auction Revenue Right ARR A financial right, awarded during the Annual ARR Allocation Process that entitles the holder to a share of the auction revenues generated in the applicable Transmission Congestion Rights (TCR) Auction(s) and/or entitles the holder to self-covert the ARRs into TCRs. IMP Glossary
Auction Revenue Right Nomination Cap ARR Nomination Cap The maximum total amount of Auction Revenue Rights (ARRs) that an eligible entity may nominate in each month and season during the Annual ARR Allocation Process and the Monthly ARR Allocation Process. IMP Glossary
Automated Generation Control   AGC Equipment that automatically adjusts generation in a Balancing Authority (BA) area from a central location to maintain the BA’s interchange schedule plus Frequency Bias. AGC may also accommodate automatic inadvertent payback and time error correction. Glossary Page NERC Glossary
Available Flowgate Capability AFC A measure of the flow capability remaining on a Flowgate for further commercial activity over and above already committed uses. It is defined as Total Flowgate Capability less Existing Transmission Commitments, less a Capacity Benefit Margin, less a Transmission Reliability Margin, plus Postbacks, and plus counterflows. Glossary Page NERC Glossary
Available Transfer Capability  ATC A measure of the transfer capability remaining in the physical transmission network for further commercial activity over and above already committed uses. Glossary Page
Balancing Authority BA The responsible entity that maintains load interchange-generation balance within a Balancing Authority Area. Also known as Control Area or Settlement Area. Glossary Page IMP Glossary
Balancing Authority Area BAA The collection of generation, transmission, and loads within the metered boundaries of the Balancing Authority. IMP Glossary
Behind the Meter Commonly refers to the flow of electricity before it hits the meter on the transmission system wires. IMP Glossary
Bid A commitment to pay a specific maximum price for a quantity of Energy or Transmission Congestion Rights (TCRs), such as a Demand, Virtual Energy, or Export Interchange Transaction Bids, and/or a TCR Bid. IMP Glossary
Bilateral Contract A direct contract between the power producer and user or broker outside of a centralized power pool or power exchange. Glossary Page FERC Order 888
Bilateral Settlement Schedule BSS A financial arrangement between two Market Participants: (1) designating the buyer, seller, MW amount and Settlement Location for Energy transactions, or (2) designating the buyer, seller, obligation percentage, and Reserve Zone for Operating Reserve obligation transfer transactions. IMP Glossary
Block Demand Response BDR A behind-the-meter load reduction that requires a calculated response. IMP Glossary
Block Demand Response Resource BDR Resource A controllable load, including controllable load of an aggregator of retail customers, that is not a dispatchable resource and that can reduce the withdrawal of Energy from the transmission grid when directed by SPP. IMP Glossary
Board of Trustees BOT An appointed or elective board that supervises the affairs of a public or private organization. Glossary Page Dictionary.com
Calibration The load-ratio share distribution of unaccounted-for Energy within a settlement area. IMP Glossary
Capability The maximum load that a generating unit, generating station or other electrical apparatus can carry under specified conditions for a given period of time without exceeding approved limits of temperature and stress. Glossary Page NERC
Capacity Amount of electric power delivered or required for which a generator, turbine, transformer, transmission circuit, station or system is rated by the manufacturer. Glossary Page NERC
Capacity (Purchased) Amount of Energy and capacity available for purchase from outside the system. Glossary Page
Capacity Benefit Margin   CBM Amount of transmission interconnection capability reserved by Load Serving Entities to ensure access to generation from interconnected systems to meet generation reliability requirements. Intended only for emergency generation deficiencies. Glossary Page
Central Prevailing Time CPT Clock time for the season of a year, i.e., Central Standard Time and Central Daylight Time. IMP Glossary
Change Working Group   CWG Coordinates and schedules any changes to the interfaces between SPP systems, processes, practices and the members/Market Participants required to implement or enhance needed functions. The CWG will recommend any process improvements or project management to other working groups to facilitate these interfaces. Glossary Page
Cleared Energy The total net quantity and Energy represented by an Asset Owner’s Day-Ahead (DA) Market-cleared Resource Offers and Demand Bids in the DA Market at Settlement Location for the hour. IMP Glossary
Close Out The end-of-the-year process used to allocate any excess congestion fund dollars to the holders of the Candidate Auction Revenue Rights (ARRs), on a pro rate share based on the Nomination Cap. IMP Glossary
Combined Cycle CC A resource configured using both gas turbines or engines and steam generators. IMP Glossary
Commercial Model A representation of the attributes of and the relationships between Market Participants, Asset Owners, resource and load assets, and PNodes for use in the Energy and Operating Reserve Markets, and Transmission Congestion Rights (TCR) Markets. IMP Glossary
Commercial Operations System COS Provides a "one-stop shop" interface to market users, receives and validates settlement data submissions (e.g., meter actuals), stores commercial data including customer information, Settlement Locations, etc. Hosted at Accenture. Glossary Page IMP Glossary
Commit Time The time specified by SPP or a local transmission operator in a commit order at which a resource should be synchronized and at or above Minimum Economic Capacity Operating Limit. IMP Glossary
Commitment Period The contiguous period of time between a resource’s Day-Ahead Market commit time and the same market’s de-commit time. See also Day-Ahead Market Commitment Period. IMP Glossary
Commitment Status A parameter submitted as part of a Resource Offer that specifies the option under which the resource is to be committed. IMP Glossary
Common Bus A single bus to which two or more resources owned by the same Asset Owner are connected in an electrically equivalent manner, where such resources may be treated as interchangeable for certain compliance monitoring purposes. IMP Glossary
Common Gateway Interface   CGI A standard for running programs over a web server. Glossary Page
Competitive Transition Charge   CTC Transition charge used to recover costs stranded by customer freedom. Glossary Page
Congestion Situation where the desired amount of electricity is unable to flow due to physical limitations (line, bus, storm damages) or regulated limitations, such as Contingency Reserves. Congestion impairs the ability to use least-cost electricity to meet demand, and a price difference between source and sink. IMP Glossary
Congestion Hedging A strategy used to reduce the risk of adverse price movements in an asset due to transmission overcrowding. IMP Glossary
Congestion Management Event CME An event during which constraints are activated in the Real-Time Balancing Market in order to re-dispatch the system to reduce the impact of SPP Market Flow on a Coordinated Flowgate or Reciprocal Coordinated Flowgate (RCF) or in order to redispatch the system to remove projected limit violation on flowgates other than a Coordinated Flowgate or RCF. This event may entail a parallel issuance of Transmission Loading Relief (TLR). IMP Protocols
Consolidated Balancing Authority CBA Assumes SPP footprint has retained existing Settlement Areas for determining residual load while supplying Net Scheduled Interchange and Net Actual Interchange for the entire footprint to calculate the impact of Net Inadvertent. IMP Protocols
Constraints Caused by a line or flowgate being overloaded or no longer available. Glossary Page
Contingency The unexpected failure or outage of a system component, such as a generator, transmission line, or other electrical element. IMP Glossary
Contingency Reserve Deployment Instruction CRD Instruction An instruction issued by SPP to resources cleared for Contingency Reserve in the Real-Time Balancing Market to deploy a specific MW quantity of Contingency Reserve as communicated as a component of the Setpoint Instructions. IMP Glossary
Contingency Reserve Deployment Period CRD Period The time period following the issuance of a Contingency Reserve Deployment Instruction within which a Resource has to deploy Contingency Reserve which is set at ten (10) minutes. IMP Protocols
Contingency Reserve Ramp Rate A curve specifying MW/minute ramp rates that are used to determine a resource’s maximum Spinning Reserve quantities or Online Supplemental Reserve quantities. IMP Glossary
Contract Header Mechanism used by Market Participants to create Bilateral Settlement Schedules for Energy and Operating Reserve obligation by registering and confirming the parameters of the agreement between buyer and seller (such as schedule ID, Settlement Location, Reserve Zone, etc.) and the effective and termination dates. The contract header is validated and entered into the system. IMP Glossary
Contract Price Price of fuels marketed on a contract basis covering a period of one (1) or more years. Contract prices reflect market conditions at the time the contract was negotiated and therefore remain constant throughout the life of the contract or are adjusted through escalation clauses. Generally, contract prices do not fluctuate widely. Glossary Page
Control Area CA A North American Reliability Corporation (NERC) operating entity bounded by interconnection (tie-line) metering or telemetering, and directly controlling generation to regulate the interconnection’s frequency. The Control Area (CA) balances schedules with load and generation to maintain its interchange schedules with other CAs. IMP Glossary
Control Area Operator   CAO Operator for Control Area. Glossary Page
Control Performance Standard   CPS Required measurement of performance of a Control Area defined in NERC Operating Policy 1. Glossary Page NERC
Control Status A parameter communicated electronically to SPP by a Market Participant at any time during an Operating Hour, indicating a resource’s ability to follow Setpoint Instructions. IMP Glossary
Controllable Load CLD Wholesale market load that can be at least partially curtailed in response to a deployment instruction. IMP Glossary
Cooperative Electric Utility   COOP An electric utility legally established to be owned by and operated for the benefit of those using its service. The utility company will generate, transmit and/or distribute supplies of electric energy to a specified area not being serviced by another utility. Such ventures are generally exempt from Federal income tax laws. Most electric cooperatives have been initially financed by the Rural Electrification Administration (REA), U.S. Department of Agriculture. Glossary Page
Co-Optimization The simultaneous/joint clearing of Energy and Operating Reserve to produce the least operational cost solution. IMP Glossary
Cost Amount paid to acquire resources, such as plant and equipment, fuel, or labor services. Glossary Page
Counter Party The opposing entity in a financial schedule. IMP Glossary
Critical Cyber Asset   CCA Asset essential to the reliable operation of Critical Assets. Critical Assets are facilities, systems, and equipment which, if destroyed, degraded, or otherwise rendered unavailable, would affect the reliability or operability of the Bulk Electric System. Glossary Page NERC Glossary
Current Operating Plan COP SPP’s internal hourly resource commitment schedule for the Operating Day resulting from the various Day-Ahead (DA) Market and DA Reliability Unit Commitment (RUC) Processes and updated, as required, during the Intra-Day RUC Process that is used as input into the Real-Time Balancing Market. IMP Glossary
Day-Ahead DA The time period starting at 0001 and ending at 2400 on the day prior to the Operating Day. IMP Glossary
Day-Ahead Make Whole Payment Amount DA MWP Amount A credit or charge to an Asset Owner, calculated for each resource with an associated Day-Ahead Market commitment period. IMP Glossary
Day-Ahead Market DA Market The financially binding market for Energy and Operating Reserve that is conducted on the day prior to the Operating Day. IMP Glossary
Day-Ahead Market Commitment Period DA Market Commitment Period The contiguous period of time between a resource’s Day-Ahead (DA) Market commit time and DA Market de-commit time. See all Commitment Period. IMP Glossary
Day-Ahead Reliability Unit Commitment DA RUC The SPP process following the Day-Ahead Market’s close and prior to the Operating Day (OD) to assess resource and Operating Reserve adequacy for the OD, commit and/or de-commit resources as necessary, and communicate resource commitments or de-commitments to the appropriate Market Participants, when necessary. IMP Glossary
Day-Ahead Schedule DA Schedule Schedule prepared by a scheduling coordinator or the Independent System Operator (ISO) before the beginning of each trading day. This schedule indicates the generation levels and demand scheduled for each settlement period that trading day. IMP Glossary
De-Commit Time The time specified by SPP or a local transmission operator in a de-commit order at which a resource should begin de-synchronization procedures. IMP Glossary
Demand Bid A Market Participant proposal associated with a physical load to purchase a fixed or price-sensitive amount of Energy at a specified location and period of time in the Day-Ahead Market. IMP Glossary
Demand Curve A series of quantity/price points used to set Operating Reserve Market Clearing Prices when there is an Operating Reserve supply shortage, and to set Locational Marginal Prices when there is shortage of capacity to meet Energy requirements. IMP Glossary
Demand Response Load DRL A measurable load capable of being reduced at the SPP operator’s instruction, and subsequently increased at the instruction of the SPP operator that is identified in the registration of a Dispatchable Demand Response Resource or a Block Demand Response Resource. IMP Glossary
Demand Response Resource DRR A Dispatchable Demand Response Resource or a Block Demand Response Resource. See Controllable Load. Glossary Page IMP Glossary
Deployment Intervals   DI A 5-minute period. Each Operating Hour has 12 deployment intervals. Glossary Page
Designated Agent   DA The Transmission Customer (TC), if preferred, can designate another TC, referred to as the Designated Agent (DA) to be responsible for its Market Participants (MPs). The DA is an SPP TC who is financially responsible for assets within the SPP footprint that it does not legally own. This is typically seen in the transmission market. Glossary Page
Designated Resource Any designated generation resource owned, purchased, or leased by a Transmission Customer (TC) to serve load in the SPP region. Designated resources do not include any resource, or any portion thereof, that is committed for sale to third parties or otherwise cannot be called upon to meet the TC's load on a non-interruptible basis. IMP Glossary
Desired Dispatch A MW value calculated from a resource’s Real-Time Balancing Market (RTBM) Energy Offer curve that represents the point at which the resource’s incremental Energy Offer is equal to the resource’s RTBM Locational Marginal Price (LMP). IMP Glossary
Direct Current   DC An electric current flowing in one direction only and substantially constant in value. Glossary Page Merriam-webster.com
Dispatch Instruction The communicated resource target Energy MW output level at the end of the Dispatch Interval. SPP sends Dispatch Instructions to each resource in the market. Glossary Page IMP Glossary
Dispatch Interval The period of time for which SPP issues Energy Dispatch Instructions and clears Operating Reserve in the Real-Time Balancing Market. The Dispatch Interval is currently five minutes. IMP Glossary
Dispatch Status A parameter submitted as part of a Resource Offer that specifies the option under which the resource is to be dispatched, once the resource has been committed and becomes a synchronized resource. IMP Glossary
Dispatchable Controllable Load A registered load Settlement Location within which the associated Demand Response Load resides, associated with a Dispatchable Demand Response Resource. IMP Glossary
Dispatchable Demand Response DDR Load reduction which can be metered. IMP Glossary
Dispatchable Demand Response Resource DDR Resource A controllable load, including behind-the meter generation, that is a dispatchable resource and can reduce the withdrawal of Energy from the transmission grid when directed by SPP. IMP Glossary
Dispatchable Resource A resource for which an Energy Offer curve has been submitted and that is available for dispatch by SPP on a dispatch interval basis. IMP Glossary
Dispatchable Variable Energy Resource DVER A variable energy resource capable of being incrementally dispatched down by the transmission provider. IMP Glossary
Distributed Common Object Model   DCOM A technology for component-based development of software that is network-aware. Using Distributed Component Object Mode (DCOM)l, developers can create network-aware applications using Component Object Model components. DCOM works under various network transports, including Transmission Control Protocol/Internet Protocol (TCP/IP). Glossary Page thenetworkencyclopedia.com
Disturbance Control Standard  DCS Standard to measure the application of Contingency Reserves. Glossary Page NERC
Disturbance Monitoring Equipment   DME That equipment that monitors power system disturbances. Glossary Page
Dynamic Schedule A telemetered reading or value that is updated in real time and used as a schedule in the Automatic Generation Control (AGC) and Area Control Error (ACE) equation. The integrated value is treated as a schedule. Commonly used for "scheduling" jointly owned generation or remote load to or from another Control Area. Glossary Page
Electric Industry Registry EIR Serves as a central repository of information that is required for commercial interactions. IMP Protocols
Electric Plant (Physical) A facility containing prime movers, electric generators, and auxiliary equipment for converting mechanical, chemical and/or fission energy into electric energy. Glossary Page
Electric Utility A corporation, person, agency, authority or other legal entity or instrumentality that owns and/or operates facilities within the United States, its territories, or Puerto Rico for the generation, transmission, distribution, or sale of electric energy primarily for use by the public and files forms listed in the Code of Federal Regulations, Title 18, Part 141. Facilities that qualify as co-generators or small power producers under the Public Utility Regulatory Policies Act (PURPA) are not considered electric utilities. Glossary Page
Electrical Node ENode A physical node represented in the Network Model where electrical equipment and components are connected. IMP Glossary
Eligible Entity A Transmission Customer or Market Participant eligible to nominate Auction Revenue Rights (ARRs) during the Annual ARR Allocation Process. IMP Glossary
Emergency An abnormal system condition requiring manual or automatic action to maintain system frequency, or to prevent loss of firm load, equipment damage, or tripping system elements that could adversely affect the electric system’s reliability or the safety or persons or property. IMP Glossary
Energy An amount of electricity that is bid or offered, produced, purchased, consumed, sold or transmitted over a period of time, which is measured or calculated in megawatt hours (MWh). IMP Glossary SPP Tariff
Energy and Operating Reserve Markets The Day-Ahead Market and Real-Time Balancing Market. IMP Glossary
Energy Charge That portion of the charge for electric service based upon the electric energy (kWh) consumed or billed. Glossary Page
Energy Emergency Alert   EEA Procedure initiated by the Load Serving Entity’s (LSE's) Reliability Coordinator, who declares various Energy Emergency Alert levels as defined in Attachment 1-EOP-002 of the NERC Standards. Energy Emergency Alert Levels provide assistance to the LSE when it can no longer provide its customers' expected energy requirements. Glossary Page NERC Standards
Energy Management System   EMS The software system used by SPP for the real-time acquisition of operating data and operations. The EMS gathers and analyzes data sent to it from many locations within and external to the Regional Transmission Organization (RTO) footprint. It analyzes data and alerts coordinators of problems (e.g., line overloads) that may threaten the reliability of the system. Glossary Page IMP Glossary
Energy Market Exists when competing generators/suppliers offer their electricity output to customers. SPP facilitates the Integrated Marketplace, overseeing the activities of the Marketplace, insuring reliability and forecasting supply requirements. Glossary Page
Energy Offer Curve A set of price/quantity pairs that represents the offer to provide Energy from a resource. IMP Glossary
Energy Schedules There are two primary types of schedules: (1) "energy schedules" which itemize the estimate of flow in MW-hour units, and (2) "capacity schedules" which itemize the estimate of flow in MW units. SPP currently uses only energy schedules in the WebTrans. Energy schedules reflect bilateral and self-scheduled activities. Glossary Page
Energy Source The primary source that provides the power that is converted to electricity through chemical, mechanical or other means. Energy sources include coal, petroleum and petroleum products, gas, water, uranium, wind, sunlight, geothermal and other sources. Glossary Page
Excess Regulation-Down Mileage Settled Regulation-Down mileage that exceeds the amount of Expected Regulation-Down Mileage. IMP Protocols
Excess Regulation-Up Mileage Settled Regulation-Up mileage that exceeds the amount of Expected Regulation-Up Mileage. IMP Protocols
Expected Regulation-Down Mileage Regulation-Down mileage included as part of the market clearing that is equal to the amount of Regulation-Down cleared multiplied by the Regulation-Down Mileage Factor. IMP Protocols
Expected Regulation-Up Mileage Regulation-Up mileage included as part of the market clearing that is equal to the amount of Regulation-Up cleared multiplied by the Regulation-Down Mileage Factor. IMP Protocols
Export Interchange Transaction A Market Participant schedule for exporting Energy out of the SPP Balancing Authority Area. IMP Glossary
Export Interchange Transaction Bid A Market Participant proposal to purchase a fixed or price-sensitive amount of Energy in the Day-Ahead Market, or a fixed amount of Energy in the Real-Time Balancing Market for delivery outside of the SPP Balancing Authority Area at a specified external interface and period of time. IMP Glossary
Extensible Markup Language Schema Definition   XSD Ensures that the information in your XML document is in a correct and consistent format and that all the necessary information has been included. Glossary Page
Extensible Markup Language   XML A flexible way to create standard information formats and share both the format and the data on the World Wide Web. Glossary Page
External Contingency Reserve The sum of the external Spinning Reserve and external Supplemental Reserve. IMP Glossary
External Interface A Settlement Location representing a physical interconnection point(s) between the SPP Balancing Authority Area (BAA) and an external BAA. IMP Glossary
External Reserve Zone Obligation Transfer Schedule A schedule from a Balancing Authority (BA) external to the SPP BA, into a Reserve Zone support by firm transmission service to the SPP border and that allows a Market Participant to reduce its Operating Reserve obligation in that Reserve Zone. IMP Glossary
External Spinning Reserve Spinning Reserve contracted by a Market Participant (MP) being supplied from an external Balancing Authority (BA) to a Reserve Zone within the SPP BA to meet the MPs’ Spinning Reserve obligation in that zone. IMP Glossary
External Supplemental Reserve Supplemental Reserve contracted by a Market Participant (MP) and supplied from an external BA to a Reserve Zone within the SPP BA to meet the MPs’ Supplemental Reserve obligation within the zone. IMP Glossary
Extra High Voltage   EHV Voltage in excess of 345 kilovolts, or 345,000 volts. Glossary Page Dictionary.com
Federal Energy Regulatory Commission   FERC Quasi-independent regulatory agency within the Department of Energy having jurisdiction over interstate electricity sales, wholesale electric rates, hydroelectric licensing, natural gas pricing, oil pipeline rates and gas pipeline certification. Glossary Page NERC
Firm Point-to-Point Auction Revenue Rights Nomination Cap Firm PTP ARR Nomination Cap The maximum total amount of Firm Point-to-Point (FPTP) Candidate Auction Revenue Rights (ARRs) that an eligible entity may nominate in each month and season in the Annual ARR Allocation Process. IMP Glossary
Firm Point-to-Point Transmission Service Firm PTP Transmission Service The highest quality or priority service offered to customers under a filed rate schedule that anticipates no planned interruption. Point-to-point transmission service is the transmission of capacity and Energy from the point(s) of receipt to the point(s) of delivery. IMP Glossary
Firm Power The power or power-producing capacity intended to be available at all times during the period covered by a guaranteed commitment to deliver, even under adverse conditions. Glossary Page
Flowgate A transmission facility or transmission element(s) that has been identified as limiting the amount of power that can be reliably transferred over the bulk transmission system. IMP Glossary
Forced Outage The shutdown of a generating unit, transmission line or other facility, for emergency reasons or a condition in which the generating equipment is unavailable for load due to unanticipated breakdown. Glossary Page
Generating Unit Any combination of physically connected generator(s), reactor(s), boiler(s), combustion turbine(s) or other prime mover(s) operated together to produce electric power. Glossary Page
Generation (of Electricity) The process of producing electric energy by transforming other forms of energy; also, the amount of electric energy produced, expressed in watthours (Wh). Glossary Page
Generation Company  GenCo A regulated or non-regulated entity (depending upon the industry structure) that operates and maintains existing generating plants. The generation company may own the generation plants or interact with the short-term market on behalf of plant owners. In the context of restructuring the market for electricity, the generation company is sometimes used to describe a specialized "marketer" for the generating plants formerly owned by a vertically-integrated utility. Glossary Page
Generation Control Area GCA The Control Area or Settlement Area in which the schedule originates. IMP Glossary
Generator Nameplate Capacity The full-load continuous rating of a generator, prime mover or other electric power production equipment under specific conditions as designated by the manufacturer. Installed generator nameplate rating is usually indicated on a nameplate physically attached to the generator. Glossary Page
Grandfathered Agreement GFA Transmission agreements executed prior to the SPP Open Access Transmission Tariff’s effective date. IMP Glossary
Grandfathered Firm Point-to-Point Candidate Auction Revenue Right All or a portion of the MW quantity of the Grandfathered Agreement's (GFA’s) transmission service component providing service equivalent to Firm Point-to-Point (FPTP) transmission service, as defined in the SPP Tariff, verified prior to the start of the Annual Auction Revenue Right (ARR) Allocation Process, that the applicable eligible entity can nominate for conversion into an ARR in the Annual ARR Allocation Process. IMP Glossary
Grandfathered Network Integration Transmission Service Auction Revenue Right Nomination Cap GFA NITS ARR Nomination Cap The maximum total amount of Grandfathered Agreement Network Integration Transmission Service (NITS) Candidate Auction Revenue Rights (ARRs) an eligible entity may nominate in each month and season in the Annual ARR Allocation Process. IMP Glossary
Grandfathered Network Integration Transmission Service Candidate Auction Revenue Right GFA NITS Candidate ARR All or a portion of the MW quantity of a Grandfathered Agreement's (GFA's) transmission service component providing service equivalent to Network Integration Transmission Service (NITS), as defined in the SPP Tariff, verified prior to the start of the Annual Auction Revenue Right (ARR) Allocation Process, that the applicable eligible entity can nominate for conversion into an ARR. IMP Glossary
Grid A term often referring to one or more interconnected electrical systems. Glossary Page
Gross-Up Load Amount by which a dispatchable controllable load or a block controllable load is increased to account for the load reduction associated with the dispatch of a Dispatchable Demand Response Resource or Block Demand Response Resource. IMP Glossary
Hub A Settlement Location consisting of an aggregation of Price Nodes developed for financial and trading purposes. See Resource Hub, Trading Hub, or Market Hub. IMP Glossary
Hypertext Transfer Protocol   HTTP The set of rules for exchanging files (text, graphic images, sound, video and other multimedia files) on the World Wide Web (WWW). Glossary Page
Imbalance Energy   IE The difference between what actually happens for each generator and load and what they prearranged through schedules. Mathematically the IE can be expressed as follows: IE = Actual Production or Usage - Scheduled Production or Usage. Glossary Page
Import Interchange Transaction A Market Participant schedule for importing Energy into the SPP Balancing Authority Area. IMP Glossary
Import Interchange Transaction Offer A Market Participant proposal to purchase a fixed or price-sensitive amount of Energy in the Day-Ahead Market or a fixed amount of Energy in the Real-Time Balancing Market for delivery into the SPP Balancing Authority Area at a specified external interface and period of time. IMP Glossary
Incremental Energy Cost The cost of producing and transporting the next available unit of electrical power. IMP Glossary
Independent Power Producer  IPP An entity that is also considered non-utility power producer in the United States. IPPs are wholesale electricity producers that operate within the franchised service territories of host utilities and are usually authorized to sell at market-based rates. Unlike traditional electric utilities, IPPs do not possess transmission facilities or sell electricity in the retail market. Glossary Page
Independent System Operator ISO An independent entity regulated by the Federal Government that coordinates regional transmission in a non-discriminatory manner and ensures the safety and reliability of the electric system. Glossary Page
Injection The input of energy into the grid; the MW quantity is denoted as negative (-) in the imbalance energy equation. Glossary Page
Interchange Distribution Calculator   IDC System used to assist Security Coordinators in determining what transmission service and schedules are affecting critical transmission system constraints. Glossary Page NERC
Interchange Schedule An arrangement between parties for electrical transactions that cross Control Area boundaries. It is an agreed upon transaction that includes size (MWs) start and end time, ramp times and type of service for delivery and receipt of power and energy between source and sink entities. Glossary Page
Interchange Transaction Any Energy transaction crossing the boundary of the SPP Balancing Authority Area (BAA) and requires checkout with one or more external BAAs. This includes any import-interchange transaction, export-interchange transaction, and/or through-interchange transaction. IMP Glossary
Inter-Control Center Communications Protocol ICCP Provides a communication protocol for real-time data exchange between control centers. The electric power industry depends on real-time information exchange and communication of operating data to for the generation, transmission and distribution of electricity. Glossary Page International Electrotechnical Commission (IEC)
Inter-Regional Security Network Data Definition Fi   ISNDDF A list of all data that can be exchanged in real-time by using the ICCP Protocol. Glossary Page IEC
Interruptible Load Refers to program activities that, in accordance with contractual arrangements, can interrupt consumer load at times of seasonal peak load by direct control of the utility system operator or by action of the consumer at the direct request of the system operator. It usually involves commercial and industrial consumers. In some instances the load reduction may be affected by direct action of the system operator (remote tripping) after notice to the consumer in accordance with contractual provisions. For example, loads that can be interrupted to fulfill planning or Operating Reserve requirements should be reported as Interruptible Load. Interruptible Load as defined here excludes Direct Load Control and Other Load Management. (Interruptible Load, as reported here, is synonymous with Interruptible Demand reported to the North American Electric Reliability Council on the voluntary Form EIA-411, "Coordinated Regional Bulk Power Supply Program Report," with the exception that annual peak load effects are reported on the Form EIA-861 and seasonal (i.e., summer and winter) peak load effects are reported on the EIA-411). Glossary Page
Intra-Day Reliability Unit Commitment Intra-Day RUC or ID RUC SPP process following the completion of the Day-Ahead (DA) Reliability Unit Commitment (RUC) and throughout the Operating Day (OD) to assess resource and Operating Reserve adequacy for the OD, commit and/or de-commit resources as necessary, and communicate commitment or de-commitment of resources to the appropriate Market Participants, as necessary. IMP Glossary
Joint Transmission Services Network   JTSIN Group of regional councils and transmission providers that jointly developed the "JTSIN" OASIS which gives customers single logins and a common interface. Glossary Page
Jointly Owned Resource JOU A resource owned by more than one Asset Owner. IMP Glossary
Kilovolts kV Measure of voltage for transmission, thousands of volts. Glossary Page
Line Outage Distribution Factor   LODF Represents the percentage of flow on a contingent facility that will flow on the monitored elements, if the contingent facility is outaged Glossary Page NERC
Load The amount of electric power delivered or required at any specific point or points on a system. The requirement originates at the consumers’ Energy-consuming equipment. IMP Glossary
Load Control Area LCA The Control Area or Settlement Area in which the schedule sinks. IMP Glossary
Load Forecast Data used to determine obligation calculations and accessed through the Marketplace Portal. Load forecasts include weather data and hourly load data. IMP Glossary
Load Ration Share The percentage of load at a single Settlement Location relative to SPP’s total load. IMP Glossary
Load Serving Entity LSE The entity that serves the end-use customer’s Energy requirements. IMP Glossary
Locational Marginal Price LMP The market-clearing price for Energy at a given Price Node equivalent to the marginal cost of serving demand at the Price Node while meeting SPP Operating Reserve requirements. IMP Glossary
Loss Pool A collection of Settlement Locations dynamically determined for each Asset Owner based on that owner’s transactional activity, used to determine the Asset Owner’s allocation of over-collected loss revenues. IMP Glossary
Loss Rebate Factors constructed by multiplying the portion of the net withdrawal served from within the loss pool at the Settlement Location by the delta between the local Marginal Loss Component (MLC) and the local loss pool’s injection weighted average MLC, and summing that portion of the net withdrawal served by the exchange at the Settlement Location by the delta between the local MLC and the exchange injection weighted average MLC. IMP Glossary
Manual Dispatch Instruction A Dispatch Instruction created outside of the normal Real-Time Balancing Market (RTBM) Security Constrained Economic Dispatch (SCED) Dispatch Instruction solution to address a system reliability condition that could not be resolved by the RTBM SCED. IMP Glossary
Marginal Congestion Component MCC A Locational Marginal Price (LMP) component representing congestion’s marginal cost. IMP Glossary
Marginal Energy Component MEC A Locational Marginal Price (LMP) component representing Energy’s marginal cost. IMP Glossary
Marginal Loss Component MLC A Locational Marginal Price (LMP) component representing the marginal losses at Price Node relative to the network distributed load bus. IMP Glossary
Market Activities The day-ahead, Operating Day, hour-ahead and Operating Hour market activities are represented using this animation module. Glossary Page
Market Clearing Price MCP The price used for settlements of an Operating Reserve product in each Reserve Zone. A separate price is calculated for Regulation-Up, Regulation-Down, Spinning Reserve, and Supplemental Reserve. IMP Glossary
Market Flow The impact on transmission system flowgate flows resulting from an operational entity’s Resources serving market load within a defined market footprint. IMP Protocols
Market HUB A Resource Hub or Trading Hub. IMP Protocols
Market Operations System   MOS A real-time system which performs Security Constrained Economic Dispatch (SCED), generates setpoint Dispatch Instructions for each resource, computes nodal price for each Price Node (generator or load location). MOS provides Ancillary Service (AS) Plan, Resource Offer, offer curve input and analysis functions. Glossary Page
Market Participant MP Any person or entity that directly participates in and/or receives services from SPP markets and services. An MP can buy and sell SPP services under its Open Access Transmission Tariff. IMP Glossary
Market Portal Web-based interface for users to upload meter actual submissions, view Settlement Statements, access user "roles" (privileges), track service requests, change registration information and file disputes with Settlement Statements. Glossary Page
Market Power The ability to cause prices to deviate from competitive levels by controlling the provision of generation capacity or transmission capacity to the market, whether by "physical" withholding or "economic" withholding. Glossary Page
Market Protocols Detailed procedures that implement SPP’s governing documents relating to Energy and Operating Reserve markets operations, Transmission Congestion Rights (TCR) Market, settlements, and market mitigation. IMP Glossary
Market Re-dispatch  MRD Defines the provision by a marketing entity of a re-dispatch of generation to create Available Transfer Capability in order to allow another schedule to flow that would otherwise have been curtailed. Glossary Page
Market User Interface   MUI or Market UI Provides interactive screens to the Portal to view Resource Offers, Ancillary Service (AS) Plans and offer information. The MUI also provides an Application Programmable Interface (API) for automated data submission and sends out resource set points. Glossary Page
Market Working Group   MWG Responsible for the development and coordination of changes necessary to support any SPP administered wholesale market(s), including energy, congestion management and market monitoring consistent with direction from the Board of Directors including FERC Order 2000. MWG information (such as the calendar of events, meeting minutes, project status, etc.) can be located on the Market Working Group's Committee Page. Glossary Page
Maximum Daily Energy The maximum amount of Energy in MWh available to be produced in an Operating Day from a particular resource. IMP Glossary
Maximum Daily Starts The maximum number of times a resource can be started within an Operating Day. IMP Glossary
Maximum Demand The greatest of all demands of the load that has occurred within a specified period of time. Glossary Page
Maximum Economic Capacity Operating Limit An economic MW level at or below a resource’s Maximum Normal Capacity Operating Limit, used for constraining Energy dispatch and Contingency Reserve clearing during normal system conditions. IMP Glossary
Maximum Emergency Capacity Operating Limit The maximum MW level at which a resource, other than a Block Demand Response Resource, may operate under emergency system conditions. IMP Glossary
Maximum Emergency Capacity Run The maximum length of time a resource can operate below its Minimum Normal Capacity Operating Limit down to its Minimum Emergency Capacity Operating Limit. IMP Glossary
Maximum Normal Capacity Operating Limit The maximum MW level at which a resource may operate continuously. IMP Glossary
Maximum Normal Capacity Run Time The maximum length of time a resource can operate above its Maximum Normal Capacity Operating Limit up to its Maximum Emergency Capacity Operating Limit.
Maximum Quick-Start Response Limit The maximum amount of Supplemental Reserve that can be provided by a Quick-Start resource from an offline state. IMP Glossary
Maximum Regulation Capability A resource’s regulation ramp rate multiplied by the regulation response time. IMP Glossary
Maximum Regulation Capacity Operating Limit The maximum MW level at which a regulation-qualified resource, a regulation-up qualified resource, or a regulation-down qualified resource may operate while providing Regulation deployment. IMP Glossary
Maximum Run Time The maximum length of time a resource can run from the time it is synchronized to the time it is offline. IMP Glossary
Maximum Weekly Starts The maximum number of times a resource can be started within a rolling seven-day period. IMP Glossary
Mega Volt Amperes   MVA Apparent Power [volt-amperes]. Glossary Page
Megavar   MVAR Defined as the reactive part of complex power [volt-amp reactive]. Glossary Page
Megawatt   MW A watt is the unit of measure of the instantaneous demand for energy, or rather, for electrical work. One MW is equal to one million watts. Glossary Page IMP Glossary
Megawatthour   MWh A measurement unit of the demand for energy over the time period of one hour. One MWh is equivalent to 1,000,000 watts of electric energy used for one hour. Glossary Page
Member Test Environment MTE A hardware and software environment that will be loaded with full application instances, enabling business validations and system processing. spp.org
Memorandum of Understanding   MOU Agreement of understanding to work together for certain goals. Glossary Page
Meter Agent MA Entity responsible for submittal of revenue quality interchange, resource, and load meter data into Settlements through the Market Portal. IMP Glossary
Meter Data Submittal Location MDSL One or more meter Settlement Locations for which meter data is submitted to SPP by the Meter Agent for settlement purposes. IMP Glossary
Meter Settlement Location MSL The effective point at which a Market Participant's registered load and resources interchange Energy with the Real-Time Balancing Market. IMP Glossary SPP Tariff
Metering Parties All parties identified in a transmission service agreement that have a vested interest in the meter data’s accuracy. IMP Glossary
Mid-America Regulatory Conference   MARC Represents an association of regional organizations of utility and energy regulatory agencies from 14 states that include: Arkansas, Kansas, Illinois, Indiana, Iowa, Michigan, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, South Dakota, Texas and Wisconsin. The MARC sponsors an annual meeting and conference of Commissioners and staff from member state agencies, as well as representatives of regulated industries and the public at large, to share ideas and discuss regulatory and policy issues affecting their states, region and the nation. Glossary Page marc-conference.org
Mid-Term Load Forecast MTLF A Settlement Area load forecast developed by SPP on a rolling hourly basis for the next seven days for input into Reliability Unit Commitment. IMP Glossary
Minimum Down Time The minimum length of time required following de-synchronization that a resource must remain offline prior to a subsequent synchronization. IMP Glossary
Minimum Economic Capacity Operating Limit A MW level, at or above a resource’s Minimum Normal Capacity Operating Limit, used for Energy dispatch at a minimum level during normal operating conditions. IMP Glossary
Minimum Emergency Capacity Operating Limit The minimum MW level at which a resource other than a Block Demand Response Resource may operate under emergency system conditions. IMP Glossary
Minimum Emergency Capacity Run Time The maximum length of time a resource can operate below its Minimum Normal Capacity Operating Limit down to its Minimum Emergency Capacity Operating Limit. IMP Glossary
Minimum Normal Capacity Operating Limit The minimum MW level at which a resource may operate continuously. IMP Glossary
Minimum Regulation Capacity Operating Limit The minimum MW level at which a regulation-qualified resource, a regulation-up qualified resource, or a regulation-down qualified resource may operate while providing Regulation deployment. IMP Glossary
Minimum Run Time The minimum length of time a resource must run from the time it is put online to the time it is shut down. IMP Glossary
Min-to-Off-Time The time for a resource to de-synchronize from the grid starting from the resource’s Minimum Economic Capacity Operating Limit. IMP Glossary
Mitigated Energy Offer Curve A set of price/quantity pairs that represents the Mitigated Energy Offer, where such offers are developed in accordance with guidelines detailed in Integrated Marketplace Protocols Appendix G, to provide Energy from a resource. IMP Glossary
Mitigated No-Load Offer The mitigated compensation request in a Mitigated Resource Offer, where such compensation offers are developed in accordance with guidelines detailed in Appendix G, in dollars, by a Market Participant representing the hourly fee for operating a synchronized resource at zero MWs. IMP Glossary
Mitigated Regulation-Down Mileage Offer The Mitigated Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a regulation-qualified resource or a regulation-down qualified resource offers sell Expected Regulation-Down in dollars per MW. IMP Protocols
Mitigated Regulation-Down Offer The Mitigated Resource Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a regulation-qualified resource or a regulation-down qualified resource offers to sell Regulation-Down in dollars per MW. IMP Glossary
Mitigated Regulation-Up Mileage Offer The Mitigated Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a regulation-qualified resource or a regulation-up qualified resource offers to sell Expected Regulation-Up in dollars per MW. IMP Protocols
Mitigated Regulation-Up Offer The Mitigated Resource Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a regulation-qualified resource or a regulation-up qualified resource offers to sell Regulation-Up in dollars per MW. IMP Glossary
Mitigated Resource Offer The combination of a resource’s Mitigated Start-Up Offer, Mitigated No-Load Offer, Mitigated Energy Offer Curve, Mitigated Regulation-Up Offer, Mitigated Regulation-Down Offer, Mitigated Spinning Reserve Offer, and Mitigated Supplemental Reserve Offer. Mitigated Resource Offer parameters are developed in accordance with guidelines detailed in Appendix G and are intended to capture the incremental cost, including the appropriate application of opportunity costs, of providing each service to the SPP Energy and Operating Reserve Markets. IMP Glossary
Mitigated Spinning Reserve Offer The Mitigated Resource Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a spin-qualified resource offers to sell Spinning Reserve in dollars per MW. IMP Glossary
Mitigated Start-Up Offer The mitigated compensation request in a Mitigated Resource Offer, where such compensation offers are developed in accordance with guidelines detailed in Appendix G, required by a Market Participant for bringing an offline resource online or for reducing consumption of a Dispatchable Demand Response Resource or Block Demand Response Resource. IMP Glossary
Mitigated Supplemental Reserve Offer The Mitigated Resource Offer, where such offers are developed in accordance with guidelines detailed in Appendix G, at which a supplemental-qualified resource offers to sell Supplemental Reserve in dollars per MW. IMP Glossary
Multi-Day Reliability Assessment MDRA The process performed prior to the Operating Day (OD) to assess resource adequacy for the OD, commit resources with long start-up times that cannot be considered as part of the Day-Ahead (DA) Market or DA Reliability Unit Commitment (RUC), and communicate commitment of such resources as necessary. IMP Glossary
National Information Protection Center   NIPC Center where critical infrastructure incidents are detected and analyzed. Glossary Page
Native Load Schedule   NLS A type of schedule that is within a Control Area from a customer's designated resource to its designated load. Glossary Page
Net Actual Interchange NAI The algebraic sum of all metered interchange over all interconnections between two physically adjacent Balancing Authority areas. IMP Glossary
Net Capability The maximum load-carrying ability of the equipment, exclusive of station use, under specified conditions for a given time interval, independent of the characteristics of the load. Capability is determined by design characteristics, physical conditions, adequacy of prime mover, energy supply, and operating limitations such as cooling and circulating water supply and temperature, headwater and tailwater elevations and electrical use. Glossary Page
Net Generation Gross generation minus plant use from all electric utility owned plants. The energy required for pumping at a pumped-storage plant is regarded as plant use and must be deducted from the gross generation. Glossary Page
Net Inadvertent The difference between the Balancing Authority's Net Actual Interchange and Net Scheduled Interchange. IMP Glossary
Net Scheduled Interchange NSI The algebraic sum of all Interchange Schedules across a given path or between Balancing Authorities for a given period or instant in time. IMP Glossary NERC Glossary
Network Integrated Transmission Service   NITS Transmission service provided under Part II of the Tariff. IMP Glossary
Network Model A representation of the interconnected SPP transmission system’s transmission, generation, and load elements and the transmission systems of other regions in the Eastern Interconnection. IMP Glossary
Node A specific electrical bus location in the SPP EMS transmission model for which a settlement price is calculated. Glossary Page IMP Glossary
No-Load Offer The compensation request in a Resource Offer, in dollars, by a Market Participant representing the hourly fee for operating a synchronized resource at zero (0) MW output. No-load Offers are generally representative of a combination of the fuel expense required to maintain synchronous speed at zero (0) MW output for behind the meter generation (i.e. the resource is operating under a “no-load” condition) and/or ongoing hourly costs associated with manufacturing process changes associated with load consumption reductions for Dispatchable Demand Response Resources or Block Demand Response Resources. IMP Glossary
Non Performance A penalty charged to resources cleared for Regulation in the Real-Time Balancing Market (RTBM), but not following dispatch. IMP Glossary
Non-Dispatchable Variable Energy Resource NDVER A Variable Energy Resource not capable of being incrementally dispatched down by the transmission provider. IMP Glossary
Non-Firm Power The power or power-producing capacity supplied or available under a commitment having limited or no assured availability. Glossary Page
North American Electric Reliability Corporation   NERC A non-profit organization whose mission is to ensure that the Bulk Electric System in North America is reliable, adequate and secure. See www.nerc.com for more information. Glossary Page
OASIS Standards & Communication Protocol   S&CP OASIS data communication standard. Glossary Page
Offer A commitment to sell (i) a quantity of Energy at a specific minimum price such as a Resource Offer, a Virtual Energy Offer and/or an Import Interchange Transaction Offer, or (ii) a quantity of Transmission Congestion Rights at a specific minimum price, where such quantities may be submitted in 0.1 MW increments. IMP Protocols
Off-Peak The hours or other periods defined by North American Energy Standards Board (NAESB) business practices, contract, agreements, or guides as periods of lower electrical demand. IMP Glossary
On-Peak The hours or other periods defined by North American Energy Standards Board (NAESB) business practices, contract, agreements, or guides as periods of higher electrical demand. IMP Glossary
Open Access Same-Time Information System   OASIS Required method to provide information and request submission for transmission service and to allow all Transmission Customers to simultaneously view the data. Glossary Page IMP Glossary
Open Access Transmission Tariff   OATT A regulatory mandate to allow others to use a utility's transmission and distribution facilities to move bulk power from one point to another on a nondiscriminatory basis for a cost-based fee. Glossary Page FERC Order 888
Operating Day   OD The daily period beginning at midnight for which transactions within SPP are scheduled. Glossary Page IMP Glossary
Operating Hour OH A 60-minute period of time during the Operating Day corresponding to a clock hour, typically expressed as hour-ending. IMP Glossary
Operating Reserve OR Resource capacity held in reserve for resource contingencies and NERC control performance compliance which includes the following products: Regulation-Up, Regulation-Down, Spinning Reserve, and Supplemental Reserve. IMP Glossary
Operating Reserve Only Resource A resource that cannot be cleared or dispatched for Energy that is qualified to provide any or all of the Operating Reserve products: Regulation-Up, Regulation-Down, Spinning Reserve, or Supplemental Reserve. IMP Glossary
Operating Reserve Service The power deployed to quickly replace generation that is lost on the power system. Glossary Page
Operating Tolerance The MW range of a resource’s actual output above and below its average Setpoint Instruction over the dispatch interval, where the resource will not be subject to charges associated with Uninstructed Resource Deviation. IMP Glossary
Operational Data Maintenance System   ODMS System to maintain node level power system models. Glossary Page
Outage The period during which a generating unit, transmission line or other facility is out of service. Glossary Page
Outage Transfer Distribution Factor    OTDF In the post-contingency configuration of a system under study, the electric Power Transfer Distribution Factor with one or more system facilities removed from service (outaged). Glossary Page NERC Glossary
Over-Collected Losses OCL Settlement of surplus related to marginal loss pricing, which is rebated based on payment of marginal losses. IMP Glossary
Parallel Flow Flow on the transmission system not scheduled with SPP, caused by entities external to the SPP market’s footprint (also known as loop flow). IMP Glossary
Payback Process used to pay back Auction Revenue Rights (ARR) and Transmission Congestion Rights (TCR) uplift dollars in months where excess funds are available. A yearly payback process pays back ARR and TCR funds carried over from the monthly process. Funds remaining after the yearly payback are allocated to the ARR holders. IMP Glossary
Peak Demand Also known as peak load, denotes the maximum power requirement of a system at a given time, or the amount of power required to supply customers at times when need is greatest. They can refer either to the load at a given moment (e.g. a specific time of day) or to averaged load over a given period of time (e.g. a specific day or hour of the day). Glossary Page energyvortex.com
Per-unit   pu Per-unit [quantity per unit = the actual quantity /base quantity]. Glossary Page
Point of Delivery   POD A location that the Transmission Service Provider specifies on its transmission system where an Interchange Transaction leaves or a Load Serving Entity receives its energy. Glossary Page NERC Glossary
Point of Receipt   POR A location that the Transmission Service Provider specifies on its transmission system where an Interchange Transaction enters or a Generator delivers its output. Glossary Page NERC Glossary
Point-to-Point Transmission Service PTP Transmission Service The reservation and transmission of capacity and Energy on either a firm or non-firm basis, from the point(s) of receipt to point(s) of delivery. IMP Glossary
Portal Internet interface between SPP and its members. IMP Glossary
Post-Operating Day Post-OD The time period starting with the day immediately following the Operating Day. IMP Glossary
Power The rate at which energy is transferred. Electrical energy is usually measured in watts. Also used for a measurement of capacity. Glossary Page
Power Generation Company   PGC Generation company or a market agent that does not own any generation. Glossary Page
Power Marketers A business entity engaged in buying, selling and marketing electricity. Power marketers do not usually own generation or transmission facilities. Power marketers, as opposed to brokers, take ownership of the electricity and are involved in interstate trade. These entities file with the Federal Energy Regulatory Commission (FERC) for status as a power marketer. Glossary Page
Power Pool An association of two or more interconnected electric systems having an agreement to coordinate operations and planning for improved reliability and efficiencies. Glossary Page
Power Transfer Distribution Factor PTDF The percentage of power transfer flowing through a facility or set of facilities (flowgate) for a particular transfer when there are no contingencies. IMP Glossary
Pre-Day-Ahead Pre-DA The time period starting six days prior to Day-Ahead (DA) and ending midnight on the day prior to DA. IMP Glossary
Price The amount of money or consideration-in-kind for which a service is bought, sold or offered for sale. Glossary Page
Price Node PNode A single node in the commercial model that has a one-to-one relationship to an ENode where Locational Marginal Prices are calculated. IMP Glossary
Price Separation The divergence in prices due to transmission congestion from one geographical area to another in an Energy market. IMP Glossary
Pseudo-Tie A telemetered reading or value updated in real time, but for which no physical tie or Energy metering actually exists. IMP Glossary
Public Utilities Regulatory Policies Act of 1978 PURPA The Public Utility Regulatory Policies Act of 1978 (PURPA) was implemented to encourage, among other things: the conservation of electric energy, increased efficiency in the use of facilities and resources by electric utilities, equitable retail rates for electric consumers, expeditious development of hydroelectric potential at existing small dams, and conservation of natural gas while ensuring that rates to natural gas consumers are equitable. One of the ways PURPA set out to accomplish its goals was through the establishment of a new class of generating facilities, which would receive special rate and regulatory treatment. Generating facilities in this group are known as qualifying facilities (QFs), and fall into two categories: qualifying small power production facilities and qualifying cogeneration facilities. Glossary Page FERC.gov
Public Utility Holding Company Act of 1935 - amend   PUHCA Also known as the Wheeler-Rayburn Act, this law was passed by the United States Congress to facilitate regulation of electric utilities, by either limiting their operations to a single state, and thus subjecting them to effective state regulation, or forcing divestitures so that each became a single integrated system serving a limited geographic area. Another purpose of PUHCA was to keep utility holding companies that were engaged in regulated businesses from engaging in unregulated businesses. Glossary Page wikipedia.org
Purchasing-Selling Entity   PSE The entity that purchases or sells, and takes title to, energy, capacity, and Interconnected Operations Services. Purchasing-Selling Entities may be affiliated or unaffiliated merchants and may or may not own generating facilities. Glossary Page NERC Glossary
Qualifying Facility   QF Under the Public Utilities Regulatory Policies Act of 1978 (PURPA) Glossary Page
Quick-Start Resource QS Resource A resource that can be started, synchronized, and inject Energy within 10 minutes of SPP notification. IMP Glossary
Ramp Sharing Applied when needed to clear sufficient amounts of Energy, Regulation-Up, and Spinning Reserve to meet requirements. Ensures ramping deficiencies across hours in the Day-Ahead Market or Real-Time Balancing Market dispatch intervals do not initiate unjustified scarcity pricing. IMP Glossary
Ramp-Rate-Down A curve specifying MW/minute ramp rates applicable between resource operating ranges, used to dispatch resources in the down direction. IMP Glossary
Ramp-Rate-Up A curve specifying MW/minute ramp rates applicable between resource operating ranges, used to dispatch resources in the up direction. IMP Glossary
REAct REAct

A law passed in 1936 as part of the New Deal that allowed the federal government to make low-cost loans to farmers who had banded together to create non-profit cooperatives for the purpose of bringing electricity to rural America.

nsp.gov
Real-Time RT The continuous time period during which the Real-Time Balancing Market is operated. IMP Glossary
Real-Time Balancing Market RTBM SPP market operated continuously in real-time to balance the system through Energy deployment and to clear Regulation-Up, Regulation-Down, Spinning Reserve, and Supplemental Reserve. IMP Glossary
Reference Bus The location on the SPP transmission system relative to which all mathematical quantities, including shift factors and penalty factors relating to physical operation, will be calculated. IMP Glossary
Regional Reliability Organization   RRO An entity that ensures that a defined area of the Bulk Electric System is reliable, adequate and secure. 2. A member of the North American Electric Reliability Council (NERC), the Regional Reliability Organization can serve as the Compliance Monitor. Glossary Page FERC
Regional Transmission Group RTG A voluntary organization of Transmission Owners, transmission users and other entities approved by the Federal Energy Regulatory Commission (FERC) to efficiently coordinate transmission planning (and expansion), operation and use on a regional (and interregional) basis. Glossary Page SPP Tariff
Regional Transmission Operator Scheduling System RTOSS Web-based service, hosted by Open Access Technology International (OATI), that is part of the SPP electronic scheduling system. IMP Glossary
Regional Transmission Organization   RTO An organization that FERC has deemed to meet certain criteria, including independence and scope. Regional Transmission Organizations are mandated by FERC to ensure reliable supplies of power, adequate transmission infrastructure, and competitive wholesale prices of electricity. Glossary Page FERC; Order 2000 SPP.org
Regulation Deployment The use of Regulation-Up and Regulation-Down through Automated Generation Control equipment to automatically and continuously adjust resource output to balance the SPP Balancing Authority Area in accordance with North American Electric Reliability Corporation (NERC) control performance criteria. IMP Glossary
Regulation Mileage Operating Tolerance The allowable percentage deviation below a resource’s Instructed Regulation-Up Mileage and/or Instructed Regulation-Down Mileage over the dispatch interval where the resource will settle based upon Instructed Regulation-Up Mileage and/or Instructed Regulation-Down Mileage versus Actual Regulation-Up and/or Actual Regulation-Down Mileage. Such percentage shall initially be set to 5%. IMP Protocols
Regulation Ramp Rate A curve specifying MW/minute ramp rates that are used to determine a resource’s maximum Regulation-Up and/or Regulation-Down quantities. IMP Glossary
Regulation Response Time The maximum amount of time allowed for a resource to move its output from zero Regulation deployment to the full amount of Regulation-Up cleared, or to move from zero Regulation deployment to the full amount of Regulation-Down cleared. IMP Glossary
Regulation   REG The governmental function of controlling or directing economic entities through the process of rulemaking and adjudication. Glossary Page
Regulation-Down Mileage Offer The price at which a regulation-qualified resource or a regulation-down qualified resource has agreed to sell Expected Regulation-Down Mileage. IMP Protocols
Regulation-Down Offer The price at which a regulation-qualified resource or a regulation-down qualified resource has agreed to sell Regulation-Down in dollars per MW. IMP Glossary
Regulation-Down Qualified Resource A resource that has met the eligibility requirements to submit Regulation-Down Offers into the Energy and Operating Reserve Markets, but has not met the eligibility requirements to submit Regulation-Up Offers into the Energy and Operating Reserve Markets. IMP Glossary
Regulation-Down Service The provision of Actual Regulation-Down Mileage associated with cleared Regulation- Down Service MW in response to Regulation Deployment instructions. IMP Protocols
Regulation-Down Service Offer The sum of (i) a Resource’s Regulation-Down Offer and (ii) that Resource’s Regulation- Down Mileage Offer multiplied by the Regulation-Down Mileage Factor. IMP Protocols
Regulation-Only Resource A regulation-up qualified resource, regulation-down qualified resource, or a regulation-qualified resource that cannot be cleared or dispatched for Energy or cleared for Contingency Reserve. IMP Glossary
Regulation-Qualified Resource A resource that has met the requirements to be eligible to submit Regulation-Up Offers and Regulation-Down Offers into the Energy and Operating Reserve Markets. IMP Glossary
Regulation-Up Mileage Offer The price at which a regulation-qualified resource or a regulation-up qualified resource has agreed to sell Expected Regulation-Up Mileage. IMP Protocols
Regulation-Up Offer The price at which a regulation-qualified resource or a regulation-up qualified resource has agreed to sell Regulation-Up in dollars per MW. IMP Glossary
Regulation-Up Qualified Resource A resource that has met the requirements to be eligible to submit Regulation-Up Offers into the Energy and Operating Reserve Markets, but has not met the requirements to be eligible to submit Regulation-Down Offers into the Energy and Operating Reserve Markets. IMP Glossary
Regulation-Up Service The provision of Actual Regulation-Up Mileage associated with cleared Regulation-Up Service MW in response to Regulation Deployment instructions. IMP Protocols
Regulation-Up Service Offer The sum of (i) a Resource’s Regulation-Up Offer and (ii) that Resource’s Regulation-Up Mileage Offer multiplied by the Regulation-Up Mileage Factor. IMP Protocols
Reliability The electric system reliability has two components: adequacy and security. Adequacy is the ability of the electric system to supply to aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to withstand sudden disturbances, such as electric short circuits or unanticipated loss of system facilities. The degree of reliability may be measured by the frequency, duration and magnitude of adverse effects on consumer services. Glossary Page
Reliability Coordinator   RC The NERC functional entity that maintains the real-time operating reliability of the Bulk Electric System within a Reliability Coordinator Area. Glossary Page NERC Functional Model
Reliability Unit Commitment RUC SPP process to assess resource and Operating Reserve adequacy for the Operating Day, commit and/or de-commit resources as necessary, and communicate resource commitments or de-commitments to the appropriate Market Participants, as necessary. IMP Glossary
Reliability Unit Commitment Make-Whole Payment RUC MWP A credit or charge to a resource Asset Owner, calculated for each resource with a Reliability Unit Commitment (RUC) commitment period. A payment is made to the owner when the sum of the resource’s eligible Real-Time Balancing Market (RTBM) Start-Up Offer costs, No-Load Offer costs, Energy Offer Curve, and Operating Reserve Offer costs associated with actual MWh amounts for Energy and cleared RTBM Operating Reserve is greater than the Energy and Operate Reserve RTBM revenues received for that resource over its RUC Make-Whole-Payment eligibility period. IMP Glossary
Reliability Unit Commitment Period RUC Period Contiguous period of time between a resource’s Reliability Unit Commitment (RUC) commit time and RUC de-commit time. IMP Glossary
Reserve Margin (Operating) Amount of unused available capability of an electric power system at peak load for a utility system as a percentage of total capability. Glossary Page
Reserve Sharing Event A request for assistance to deploy Contingency Reserve by any signatory to the Reserve Sharing Group Agreement, following the sudden loss of a resource. IMP Glossary
Reserve Sharing Group RSG A group of two or more Balancing Authorities (BAs) that collectively maintains, allocates, and supplies Operating Reserves required for each BA’s use in recovering contingencies within the group. IMP Glossary
Reserve Shutdown An SPP-approved resource shutdown requested by a Market Participant (MP) to make the resource unavailable for SPP commitment and dispatch, due to reasons other than to perform maintenance or to repair equipment. IMP Glossary
Reserve Zone RZ A zone containing a specific group of Price Nodes for which a minimum and maximum Operating Reserve requirement is established. IMP Glossary
Reserved Capacity The reservation MW between a specified source and sink associated with SPP transmission service. IMP Glossary
Resident Load The load specified in the SPP Tariff. IMP Glossary
Residual Load The sum of hourly metered interchange in a Settlement Area (SA), plus the sum of all resource Meter Data Submittal Locations (MDSL) less all other load MDSLs for that SA. IMP Glossary
Resource An asset which injects energy into the transmission grid or which reduces the withdrawal of energy from the transmission grid and may be discretely directed by the Regional Transmission Organization/Independent System Operator. These resources include generation and controllable load. Glossary Page
Resource Hub A Settlement Location consisting of an aggregation of resource Price Nodes developed for financial and trading purposes. See Hub, Market Hub, or Trading Hub. IMP Protocols
Resource Offer The combination of a resource’s Start-Up Offer, No-Load Offer, Energy Offer Curve, Regulation-Up Offer, Regulation-Down Offer, Spinning Reserve Offer, and Supplemental Reserve Offer. IMP Glossary
Resource-to-Load Distribution Factor The simulated impact of incremental power output from a specific resource (“source”) on the loading of a specific flowgate, based on delivery to a representation of the locational weighting of all loads within all Settlement Locations (“sink”). IMP Glossary
Revenue The total amount of money received by a firm from sales of its products and/or services, gains from the sales or exchange of assets, interest and dividends earned on investments, and other increases in the owner's equity except those arising from capital adjustments. Glossary Page
Revenue Neutrality A principle whereby SPP can neither benefit nor be harmed by over-collection or under-collection of revenues. Glossary Page
Revenue Neutrality Uplift RNU Charge type set up as a revenue-distribution mechanism for charges and credits that have no other method of distribution to the Market Participants. IMP Glossary
Revision Request RR A request to make additions, edits, deletions, revisions, or clarifications to the SPP Business Practices, SPP Criteria, SPP Market Protocols, and SPP Open Access Transmission Tariff including any attachments and exhibits to these documents, except for Appendix F of the Market Protocols. spp.org
Running and Quick-Start Capability The net capability of generating units that carry load or have quick-start capability. In general, quick-start capability refers to generating units that can be available for load within a 30-minute period. Glossary Page
Scarcity Price The Market Clearing Price (MCP) and Locational Marginal Price (LMP) price levels determined through the use of Demand Curves when there is insufficient Operating Reserve available to meet the Operating Reserve requirement. IMP Protocols
Scheduled Outage The shutdown of a generating unit, transmission line or other facility for inspection or maintenance, in accordance with an advance schedule. Glossary Page
Security Constrained Economic Dispatch SCED An algorithm capable of clearing, dispatching, and pricing Energy and Operating Reserve on a co-optimized basis that minimizes overall cost and enforces multiple security constraints. IMP Glossary
Security Constrained Unit Commitment SCUC An algorithm capable of committing resources to supply Energy and/or Operating Reserve on a co-optimized basis that minimizes capacity costs and enforces multiple security constraints. IMP Glossary
Service Request Market Participant requests submitted through the Portal used to document and track customer initiated issues, questions, and requests. IMP Glossary
Setpoint Instruction The real-time desired MW output signal calculated for a specific resource by SPP’s control system on a specified periodicity that is equal to the current Dispatch Instruction, plus the Regulation Deployment Instruction (which may be positive or negative), plus an adjustment to the Dispatch Instruction for Energy to account for Contingency Reserve Deployment Instructions. The Setpoint Instruction represents the resource’s desired output level and assumes the resource can attain this output instantaneously (i.e. infinite ramp rate). IMP Glossary
Settlement Area SA A geographic area within the SPP Balancing Authority Area for which transmission interval metering can account for the geographic area’s net area load. IMP Glossary
Settlement Bill Determinant Data inputs and intermediate calculations used to calculate a final result to be output to a Settlement Statement. IMP Glossary
Settlement Charge Type The end result of settlement calculations. IMP Glossary
Settlement Determinant Report A daily report of interval input, intermediate calculation, and settlement result data with full Settlement Location and transactional detail generated for each Asset Owner and Operating Day settled, either on an initial, final, or resettlement basis. Separate reports are available for 1) 5-minute data, and 2) hourly and daily data. IMP Glossary
Settlement Disputes A specific service request that can be submitted through the Portal if a Market Participant does not agree with a portion of the settlement prepared and posted by SPP. IMP Glossary
Settlement Invoice A weekly summary of the SPP Integrated Marketplace net daily charges and credits by Asset Owner and Operating Day (OD), generated for each Market Participant and containing data for all of the ODs settled, either on an initial, final or resettlement basis, during the invoice period. Only the net amounts (current total less previously invoiced - if a Final or Resettlement) for each OD contribute to the invoice amounts. IMP Glossary
Settlement Location SL A location defined for the purpose of commercial operations and settlement. A Settlement Location provides the finest granularity to calculate Day-Ahead Market and Real-Time Balancing Market settlements. IMP Glossary
Settlement Statement A daily summary of the SPP Integrated Marketplace’s total daily charges and credits by charge type and Operating Day (OD), generated for each Asset Owner and containing data for all of the ODs settled, either on an initial, final, or resettlement basis, on a single settlement execution day. The current, previous, and net amounts are included on each OD’s statement. IMP Glossary
Shadow Price A price for a commodity that measures its marginal value: the rate at which system costs could be decreased or increased by slightly increasing or decreasing, respectively, the amount of the commodity being made available. For example, the shadow price associated with a transmission constraint is equal to the change in total system production cost produced through re-dispatching the system, when incrementally relaxing that transmission-line limit. IMP Glossary
Short-Term Load Forecast STLF A Settlement Area load forecast developed by SPP on a rolling 5-minute basis for the next 120 dispatch intervals for input into the Real-Time Balancing Market. IMP Glossary
Simple Object Access Protocol  SOAP A specification that defines the XML format for messages. Glossary Page
Simultaneous Feasibility Test SFT Analysis performed during each round of the Auction Revenue Right (ARR) Nomination Process to ensure nominated Candidate ARRs do not violate any normal transmission-line thermal ratings under normal system conditions, and do not violate short-term emergency transmission-line thermal ratings following a single contingency. The Simultaneous Feasibility Test is performed consistent with the transmission-system loading analysis performed as part of the Day-Ahead Market’s Security Constrained Economic Dispatch (SCED) process. IMP Glossary
Southwest Power Pool Forecast Area SPP Forecast Area A geographic area within the SPP Balancing Authority defined by SPP based upon historical operating experience for the purposes of developing load forecasts. IMP Protocols
Southwest Power Pool Integrated Marketplace SPP Integrated Marketplace The Energy and Operating Reserve Markets and the Transmission Congestion Rights (TCR) Markets. IMP Protocols
Southwest Power Pool Region   SPP Region The geographic area of the transmission system for which SPP is the Transmission Provider. Glossary Page IMP Glossary
Southwest Power Pool Transmission SWPP Operating/Security Entity Code registered with NERC and used as the Transmission Provider code for the SPP Regional Tariff. Glossary Page
Spinning Reserve The unloaded generation that is synchronized to the system and ready to serve additional demand. Glossary Page
Spinning Reserve Offer The price at which a spin-qualified resource has agreed to sell Spinning Reserve in dollars per MW. IMP Glossary
Spin-Qualified Resource A resource that has met the requirements to be eligible to submit Spinning Reserve Offers into the Energy and Operating Reserve Markets. IMP Glossary
Spot Balancing Energy Market The term used for the trading activity observed for hourly Energy contracts with delivery within the following day. Generally, the primary purpose of a Spot Energy Market is to serve as a medium for short-term purchases and sales of Energy (thus, facilitating the transfer of Energy from generator to consumer). Glossary Page
SPP Criteria Rules to promote and protect system reliability, and that members are obligated to follow. IMP Glossary
Standards Authorization Request   SAR Form to request development of a standard. Glossary Page NERC
Standards Drafting Team   SDT Team of industry experts to draft standards. Glossary Page NERC
Start-Up Offer The compensation required by a Market Participant (MP) for bringing an offline resource online or for reducing consumption of a Dispatchable Demand Response Resource or Block Demand Response Resource. Start-Up Offers are generally representative of the out-of-pocket cost an MP incurs in starting up a generating unit from an offline state through Minimum Economic Capacity Operating Limit. Start-Up Offers for Dispatchable Demand Response Resources and Block Demand Response Resources are generally representative of a combination of an MP’s out-of-pocket costs in starting up a behind-the-meter generating unit, and/or out-of-pocket costs associated with preparing for manufacturing process changes in preparation for reducing load consumption. IMP Glossary
Start-Up Time The time required to start a resource and reach the Minimum Economic Capacity Operating Limit following receipt of an SPP start-up order. IMP Glossary
State Estimator The computer software used to estimate the electric system’s properties, based on a sample of system measurements based on current system conditions. IMP Glossary
Stored Energy Resource A device which replenishes its Energy source (water, compressed air, battery, or flywheel) by withdrawing Energy from the system. IMP Glossary
Substation The facility equipment that switches, changes or regulates electric voltage. Glossary Page
Supervisory Control and Data Acquisition SCADA Four-second resource and load bus signals from Market Participant equipment to SPP. IMP Glossary
Supplemental Reserve Generation not connected to the system but capable of serving demand within a specified time or interruptible load that can be removed from the system in a specified time. Glossary Page
Supplemental Reserve Offer The price at which a supplemental-qualified resource has agreed to sell Supplemental Reserve in dollars per MW. IMP Glossary
Supplemental-Qualified Resource A resource that has met the eligibility requirements to submit Supplemental Reserve Offers into the Energy and Operating Reserve Markets. IMP Glossary
Supply Curve The aggregation of all Transmission Customer offer curves in the SPP footprint. Glossary Page
Switching Station The facility equipment used to tie together two or more electric circuits through switches. The switches are selectively arranged to permit a circuit to be disconnected or to change the electric connection between the circuits. Glossary Page
Synchronized Resource A resource that is electrically connected to the grid by closing its circuit breaker. IMP Glossary
Sync-to-Min Time The time for a resource’s output to reach Minimum Economic Capacity Operating Limit following synchronization to the grid IMP Glossary
System (Electric) The physically connected generation, transmission, and distribution facilities operated as an integrated unit under one central management or operating supervision. Glossary Page
Tariff Establishes services to be provided and rights and obligations of the parties pursuant to those services. It specifies rates, terms, and conditions under which Transmission Customers and Market Participants participate in the Integrated Marketplace. IMP Glossary
Telemetry Electronic communication of the measurements and states related to the electric system’s elements. Telemetered information forms the basis for calculating settlement charge types, as well as determining the flows across transmission facilities and the status of circuit breakers and other devices. IMP Glossary
Through Interchange Transaction A Market Participant schedule submitted between two external interfaces for use in the Day-Ahead Market or Real-Time Balancing Market for moving Energy through the SPP Balancing Authority Area. IMP Glossary
Trading Hub A Settlement Location consisting of an aggregation of Price Nodes developed for financial and trading purposes. See Hub, Market Hub, or Resource Hub. IMP Protocols
Transaction An agreement to transfer Energy from a seller to a buyer. IMP Glossary
Transaction Management System   TMS Definition in North American Electric Reliability Corporation (NERC) of an infrastructure to consolidate data sharing (no present progress). Glossary Page NERC Committee
Transformer   XFR An electrical device for changing the voltage of Alternating Current (AC). Glossary Page
Transition State Offer An offer associated with a specific combined-cycle resource configuration, representing the cost of moving from the current configuration to another valid configuration. IMP Glossary
Transition State Time An operating parameter associated with a specific combined-cycle resource configuration, representing the time required to move from the current configuration to another valid configuration. IMP Glossary
Transmission The movement or transfer of electric energy over an interconnected group of lines and associated equipment between points of supply and points at which it is transformed for delivery to consumers or is delivered to other electric systems. Transmission is considered to end when the energy is transformed for distribution to the consumer. Glossary Page
Transmission Congestion Right TCR A financial right entitling the holder to a share of the congestion revenue collected in the Day-Ahead Market. IMP Glossary
Transmission Congestion Rights Funding TCR Funding A credit or a charge to an Asset Owner, calculated for each Transmission Congestion Right (TCR) instrument held by the owner. TCR instruments are fully funded each hour. IMP Glossary
Transmission Congestion Rights Markets TCR Markets The Auction Revenue Rights' (ARRs’) Annual and Monthly Allocation Processes and the Annual and Monthly Transmission Congestion Right (TCR) Auctions. IMP Glossary
Transmission Customer TC An eligible customer, or its designated agent, that can or does execute a transmission service agreement or can or does receive transmission service. IMP Glossary
Transmission Loading Relief TLR A procedure used to curtail Energy schedules to limit power flow across a transmission system element in order to avoid exceeding the equipment’s peak operating limits. IMP Glossary
Transmission Operator TO The North American Electric Reliability Corporation (NERC) functional entity that ensures the real-time operating reliability of the transmission assets within a Transmission Operator area. NERC Functional Model
Transmission Owner  TO The North American Electric Reliability Corporation (NERC) functional entity that owns and maintains transmission facilities. Glossary Page NERC Functional Model
Transmission Provider   TP The North American Electric Reliability Corporation (NERC) functional entity that administers the transmission tariff and provides Transmission Service to Transmission Customers under applicable transmission service agreements. Glossary Page NERC Functional Model
Transmission Reliability Margin   TRM Amount of transmission transfer capability necessary to ensure interconnected transmission network is secure under a reasonable range of uncertainties in system conditions. Glossary Page
Transmission Service The right to use high-voltage transmission lines to transfer power form a generator to a consumer. Glossary Page
Transmission Service Request TSR Submitted through the SPP Open Access Same-Time Information System (OASIS) so eligible Transmission Customers can request transmission service. IMP Glossary
Transmission System (Electric) An interconnected group of electric transmission lines and associated equipment for moving or transferring electric energy in bulk between points of supply and points at which it is transformed for delivery over the distribution system lines to consumers or is delivered to other electric systems. Glossary Page
Transmitting Utility A regulated entity which owns, and may construct and maintain, wires used to transmit wholesale power. It may or may not handle the power dispatch and coordination functions. It is regulated to provide non-discriminatory connections, comparable service and cost recovery. According to the Energy Policy Act of 1992 (EPACT), this includes any electric utility, qualifying co-generation facility, qualifying small power production facility or Federal power marketing agency which owns or operates electric power transmission facilities which are used for the sale of electric energy at wholesale. Glossary Page
Turn-Around Ramp Rate Factor A percentage factor between 0-100% applied to a Resources Ramp-Rate-Up or Ramp-Rate-Down. The factor applies only in the next dispatch interval when the resource is issued a Dispatch Instruction that is in the opposite direction of the previous Dispatch Instruction. IMP Glossary
Unaccounted for Energy   UFE Calibration difference due to profile error, difference between actual losses and tariffed losses, theft, metering error. Glossary Page
Unbundling The separating of the total process of electric power service from generation to metering into its component parts for the purpose of separate pricing or service offerings. Glossary Page
Under Frequency Load Shedding   UFLS Practice that uses relays to shed load to prevent transmission system collapse when frequency is declining. Glossary Page
Uninstructed Resource Deviation URD The average MW amount of actual resource output in a dispatch interval above or below the resource’s average Setpoint Instruction in the dispatch interval. IMP Glossary
Unused Regulation-Down Mileage The amount by which settled Regulation-Down mileage is less than the amount of Expected Regulation-Down Mileage. IMP Protocols
Unused Regulation-Up Mileage The amount by which settled Regulation-Up mileage is less than the amount of Expected Regulation-Up Mileage. IMG Protocols
Variable Energy Resource VER A device for the production of electricity that is characterized by an energy source that: (1) is renewable; (2) cannot be stored by the facility owner or operator; and (3) has variability that is beyond the control of the facility owner or operator. IMP Protocols
Virtual Energy Bid A Market Participant proposal to purchase Energy at a specified price, Settlement Location, and period of time in the Day-Ahead Market that is not associated with a physical load. IMP Glossary
Virtual Energy Offer A Market Participant proposal to sell Energy at a specified price, Settlement Location, and period of time in the Day-Ahead Market that is not associated with a physical resource IMP Glossary
Web Services A method to execute remote procedure calls via Hypertext Transfer Protocol (HTTP). Glossary Page
Wholesale Competition A system whereby a distributor of power would have the option to buy its power from a variety of power producers, and the power producers would be able to compete to sell their power to a variety of distribution companies. Glossary Page
Wholesale Power Market The purchase and sale of electricity from generators to resellers (who sell to retail customers), along with the ancillary services needed to maintain reliability and power quality at the transmission level. Glossary Page
Wholesale Sales Considered the energy supplied to other electric utilities, cooperatives, municipals, and Federal and State electric agencies for resale to ultimate consumers. Glossary Page
Wholesale Transmission Services The transmission of electric energy sold, or to be sold, at wholesale in interstate commerce. Glossary Page
Withdrawal The removal of energy from the grid; the MW quantity is denoted as positive (+) in the imbalance energy equation. Glossary Page
Zone The geographic area of the facilities of an SPP Transmission Owner (TO) or a specific combination of the TO as specified in the SPP Regional Tariff. Glossary Page