# Glossary ![hepg1banner](/sites/g/files/omnuum10586/files/styles/hwp_21_9__1920x825/public/hepg/files/hepg1banner.jpg?itok=CDd3jC0E) ## expand\_more A - F G - K L - P Q - U V - Z ## A - F Open all sections Close all sections ### Access Charge expand\_more A fee paid by an independent power producer or its customer to use a transmission company's system --- Attachments- [ picture\_as\_pdf harvard-fy.pdf ](/sites/g/files/omnuum10586/files/hepg/files/harvard-fy.pdf) --- ### Adequacy expand\_more An electric system's ability (maintenance, load following, planning for future needs, etc.) to supply the aggregate electrical demand and energy requirements of its customers at all times ### Aggregator expand\_more An entity (for profit or non-profit) that assembles generators or customer loads to achieve economies of scale and diversity among the generators or loads being combined ### Alternating Current expand\_more A flow of electricity that is uncontrollable as to direction and amount ### Ancillary Services/Interconnected Operations Services (IOS) expand\_more The services necessary to effect a transfer of electricity between purchasing and selling entities that transmission providers must include in their open access transmission tariffs; IOSs are the voluntary services that transmission providers may offer to their customers (FERC Order 888, April 24, 1996). Ancillary services include regulation and frequency response; reactive supply and voltage control from generating sources, economic dispatch, and the like ### Availability expand\_more The measure of time that a generating unit, transmission line or other facility is capable of providing service, whether the unit, line or facility is in service (expressed as a percent available for the time under consideration) ### Available Transfer Capability (ATC) expand\_more The measure of the transfer capability remaining in the physical transmission network for commercial activity beyond already committed uses ### Avoided Costs expand\_more Costs of new transmission or generation (sometimes both) that electric utilities can "avoid" by purchasing from other sources, managing demand, conservation ### Backup Power expand\_more Power provided by contract to a customer when its normal sources are unavailable ### Backup Supply Service expand\_more The interconnected operations service that provides the needed capacity and energy to transmission customers to replace the loss of generation and to cover the portion of demand that exceeds generation supplies for more than a short period Show morerefresh ## G - K Open all sections Close all sections ### Genco expand\_more An electric generation company ### Generation expand\_more Conversion of nuclear, thermal, etc. energy into electricity ### Grid expand\_more The interconnected power lines and generators that supply, transmit and distribute electric power to the customers connected to it ### Gridco expand\_more An independent company that operates an electric grid ### Hedging Contract expand\_more A financial instrument that establishes the future prices and quantities of electricity independently of the short-term market, e.g., contracts for differences, forwards, futures, and option contracts ### Hourly Market expand\_more The market in which blocs of energy are traded on an hourly basis ### Incremental Load expand\_more The portion of a generator's load that is in addition to its existing load ### Interchange expand\_more Electric power or energy that flows from one entity to another ### Interconnected System expand\_more A system consisting of two or more individual electric systems that operates synchroniously and have connecting tielines ### Interconnection expand\_more A facility that connects two transmission systems or control areas, or that connects a non-utility generator to a system or control area; (when capitalized, it refers to the North American Eastern, Western, ERCOT or Alaska electric systems) Show morerefresh ## L - P Open all sections Close all sections ### LDC expand\_more Local distribution company ### LMP (Locational Marginal Pricing) expand\_more Pricing electricity to include the costs of transmission losses, congestion and the local costs of generation (also called location-based pricing) ### Load expand\_more Any consumer of electrical energy; also, the amount of power (demand) used by a utility system, electrical device or consumer. Load can be manually or automatically curtailed or shed temporarily during times of high usage (customers have agreed beforehand to such actions) or managed to ensure a reliable electricity supply ### Load Center expand\_more An area (city, etc.) that uses large amounts of electricity (also called a load pocket) ### Load Following expand\_more Planning by utilities to ensure that electric generators operate as scheduled, based upon load forecasts (also, operating a generator to balance short-term load fluctuations) ### Load Forecasting expand\_more Planning by utilities to ensure a reliable electricity supply --- Attachments- [ picture\_as\_pdf harvard-fy.pdf ](/sites/g/files/omnuum10586/files/hepg/files/harvard-fy_0.pdf) --- ### Load Response expand\_more Reducing electricity use from the grid during peak periods to increase reliability and moderate the energy-clearing price during system-wide peak demand; reducing electric load or using qualifying emergency generators on the customer side of the meter. ### LSE (Load Serving Entity) expand\_more A transmission or distribution utility that has contractual or regulatory obligations to connect its load to the transmission grid ### Margin expand\_more The difference between net capacity (a system's total capacity resources) and net internal demand, that is generally expressed in MW for operating reserves and as a percentage of either system load or installed generating capacity for planning reserves ### Marginal Cost expand\_more The cost of providing additional electricity; "The competitive price of a MWh of electricity is equal to the additional amount it would cost to generate an additional MWh, once all current demand is met. This additional cost is commonly referred to as the marginal cost. The marginal cost of generating electricity rises as more electricity is produced, because different generators use different types and amounts of fuel_.under competition, the rising marginal cost of electricity leads to high prices when demand is high and low prices during low-demand periods." (GAO-02-828 Restructured Electricity Markets, page 13) ## Q - U Open all sections Close all sections ### QF (Qualifying Facility) expand\_more Under PURPA, a non-utility generator of electric power that has received a certificate from FERC, enabling it to sell electricity only at wholesale avoided cost to a utility ### Rate Base expand\_more Accumulated capital cost of a utility's purchased or installed facilities that serve customers ### Real Option Theory expand\_more in economics, finding reduced economies of scale and applying them across all alternatives ### Real Time Pricing expand\_more Pricing electricity based on the actual cost at the time it is demanded by a customer ### Regional Transmission Organization (RTO) expand\_more A for-profit or non-profit entity that coordinates transmission planning, operations and use on a regional and inter-regional basis and that is subject to FERC approval ### Regulatory Asset expand\_more An intangible (deferred debt cost, accelerated depreciation, etc.) that appears on a regulated utility's balance sheet and that can be recovered from ratepayers under regulation ### Reliability expand\_more The measure of performance of a bulk-power system that results in electricity being delivered to consumers within accepted standards and in the amount desired; measured by frequency, duration and magnitude of adverse impacts on the electric supply (also called system reliability). Reliability comprises both generation adequacy and system security. ### Retail Wheeling expand\_more Allowing a customer to buy electricity from a supplier of choice and transmit (wheel) it on the grid ### Revenue Cap expand\_more An alternative regulation plan that caps a utility's allowed revenues with an external index ### Schedule expand\_more An agreed-upon transaction size (measured in MW), start and end times, start and end ramp times and rates required for delivery and receipt of power and energy between contracting parties and the control areas involved in the transaction ## V - Z Open all sections Close all sections ### VAR (Volt-Amperes Reactive) expand\_more The unit of measure of the power that maintains the constant variation of the electro-magnetic fields associated with alternating-current circuits ### Vertically Integrated Utility expand\_more A utility that owns and controls generation, transmission and distribution components ### Voltage expand\_more The force that makes electricity flow; the unit of measure of electric potential ### Volumetric Wires Charge expand\_more A fee for using the transmission or distribution system that is based on the volume of electricity that is transmitted ### Wholesale Market expand\_more The bulk power market ### Wholesale Wheeling expand\_more Buying transmission services from a utility to transport (wheel) electricity to another utility, non-utility generator or a wholesale customer ### Wires Charge expand\_more Charging electric suppliers or their customers for the use of transmission or distribution wires