Aggregating Entity  {AE}
The entity responsible for end-use meter reading aggregation & application of transmission & distribution losses from tariff filings. This entity may be a DisCo or an MDMA.

Source: unknown

Alternative Dispute Resolution  {ADR}

Ancillary Service (A/S)  {A/S}
A/S is the necessary services that must be provided in the generation and delivery of electricity. As defined by the Federal Energy Regulatory Commission (FERC), they include: coordination and scheduling services (load following, energy imbalance service, control of transmission congestion); automatic generation control (load frequency control and the economic dispatch of plants); contractual agreements (loss compensation service); and support of system integrity and security (reactive power or spinning and operating reserves).

Source: FERC Order 888

Source: FERC Order 2000

Ancillary Service Plan  {A/S Plan}
The A/S Plan (also referred to as the A/S 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 A/S plan indicates transfers of obligations between TCs and, when self-arranged, which resources are providing these services.

Source: SPP

Source: Market Protocols

Approved Scheduling Entity  {ASE}
Entity responsible for submission of schedules on behalf of transmission users.

Area Control Error  {ACE}
A control area'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 an CA aka BA crossed zero.

Area Interchange Error  {AIE}
AIE is calculated as the amount of Inadvertent that is caused by the Control Area outside its obligations to the interconnection.

Assets
Assets can include individual units (generators), plants, loads acting as a resource (controllable load and demand response resource) and load zones. TCs can aggregate units into plants if the units are co-located (in relation to their injection point into the grid) and electrically equivalent (meaning they are injecting at the same voltage). A TC should have their units registered with SPP.

ATC Working Group  {ATCWG}
Reviews & monitors procedures developed by Regions for determining ATC to ensure that they are consistent with NERC's 1996 ATC Definitions & Determination Report.

Source: NERC Committee

Automated Generation Control  {AGC}

Source: SPP

Automated Reserve Sharing  {ARS}
ARS is an arrangement between several parties within and outside of SPP whereby spinning reserves are maintained by each and contributed to any member with a need for reserves, such as when a generator unit trips off line. By sharing reserves, each member carries less reserves than would be necessary if acting on its own.

Source: SPP

Available
Available is a term used on the Resource Plan (RP) that indicates a resource is "on" and dispatching energy at the level determined by the market.

Source: SPP

Source: Market Protocols

Available Flowgate Capability  {AFC}

Source: SPP

Available Transfer Capability  {ATC}
A measure of the transfer capability remaining in the physical transmission network for further commercial activity over & above already committed uses.