Glossary & Acronyms

This glossary provides general definitions for training purposes of frequently used terms. If a precise definition is needed, consult the Transmission, Markets and Services Tariff (Section I), Manual M-35 (Definitions and Abbreviations), the Participants Agreement (Section 1) and the Second Restated NEPOOL Agreement (Section 1).

A-C | D-E | F-I | L-N| O-Q | R | S-Z | Acronyms

10-minute nonspinning reserve (TMNSR) - A form of operating reserve provided by off-line generation that can be electrically synchronized to the system and increase output within 10 minutes in response to a contingency; also called 10-minute non-synchronized reserve. On-line generation that can increase output within 10 minutes also may provide this service because spinning reserve is higher quality than nonspinning reserve due to the fact that the possibility of a failed start does not exist.

10-minute spinning reserve (TMSR) - A form of operating reserve provided by on-line generation thatcan increase output within 10 minutes in response to a contingency.

30-minute operating reserve (TMOR) - A form of operating reserve provided by on-line or off-line operating reserve generation that can either increase output within 30 minutes or be electrically synchronized to the system and increase output within 30 minutes in response to a contingency. (Also see spinning and nonspinning.)

Adjusted Net Interchange (ANI) - The difference between a market participant's resources and liabilities at a location, measured in megawatt-hours. Resources include generation entitlements, cleared increment offers, external purchases of electric energy, and internal bilateral purchases for electric energy. Liabilities include load obligation, cleared decrement bids, external sales of electric energy, and internal bilateral sales for electric energy.

ancillary services- Services that ensure the reliability of and support for the transmission of electricity to serve load, including regulation and frequency response (regulation or automatic generator control), spinning reserve, nonspinning reserve, replacement reserve, and reactive supply and voltage control.

area control error (ACE) - The instantaneous difference between the net actual and scheduled interchange (i.e., transfer of electric energy between two control areas), accounting for the effects of frequency bias and correction for meter error.

asset-related demand - A dispatchable or nondispatchable physical load that has been modeled within the ISO's dispatch and settlement systems.

automatic generation control (AGC) - The automatic adjustment of a control area's generation to maintain its interchange schedule plus frequency bias.

assigned meter reader - The entity that submits to ISO the hourly and monthly megawatt-hours associated with the operation of an asset, which are used for settlement purposes.

auction revenue rights (ARR) - Entitlements to receive revenues generated by the sale of Financial Transmission Rights in a specific auction.

automatic response rate (ARR) - For generating resources that are providing regulation service, the amount of the resource's output, in megawatt-minutes, that a market participant is willing to change between the resource's regulation high limit and regulation low limit.

Balancing authority (BA) - For an area comprising a collection of generation, transmission, and loads within metered boundaries (defined by NERC to be a balancing authority area), the entity responsible for integrating resource plans for that area ahead of time, maintaining the area's load-resource balance, and supporting the area's interconnection frequency in real time. The ISO is registered with NERC as a BA and is responsible for complying with NERC standards applicable to BAs.

Balancing authority area - For compliance with NERC reliability standards, an area comprising a collection of generation, transmission, and loads within metered boundaries for which a responsible entity (defined by NERC to be a balancing authority) integrates resource plans for that area ahead of time, maintains the area's load-resource balance, and supports the area's interconnection frequency in real time. This term is used interchangeably with control area.

baseload generating unit - A generating unit used to satisfy all or part of the minimum load of the system and, as a consequence, produce electric energy continuously and at a constant rate. These units are usually economic to operate on a day-to-day basis.

bid - A request to purchase megawatts at a specific location submitted into the market user interface.

bilateral contract - A contract between buyers and sellers of wholesale electricity that provides price and other terms and conditions. A bilateral contract may or may not be settled by ISO. Types of bilateral contracts for energy that are settled by ISO are Internal Bilateral for Load, Internal Bilateral for Market and External Transactions. There are also bilateral contracts for capacity.

black-start unit - A generating unit that has the ability to start without an outside electricity supply, generally by batteries or compressed air.

bottled generation - the situation when electricity produced in one area cannot be transmitted to other areas because of a transmission constraint.

bulk electric power grid, bulk electric power system, bulk electric system, bulk power grid, bulk power system -

  1. The interconnected electrical generating resources, transmission facilities, tie lines with neighboring systems, and associated equipment used to produce and transmit electric energy, generally operated at 100 kV or higher. (ISO Operations, FERC, NERC)
  2. An interconnected electrical system consisting of generation and transmission facilities on which faults (short circuits) or disturbances (severe oscillations or changes of current, voltage, or frequency) can have significant adverse impacts outside a local area. (NPCC and ISO System Planning)
  3. A system of synchronized power providers and consumers connected by transmission and distribution lines and operated by one or more control centers. (EIA)

bus - A point of interconnection to the system where power produced becomes available for transmission. Also, an electrical conductor that serves as a common connection for two or more electrical circuits.

busbar - Large rigid conductors typically used in substations to feed and direct power to two or more circuits.

capability period - Is one of two specific time periods within a power year. The summer period is June 1 through September 30; the winter period is October 1 through May 31.

capacity - The rated and continuous load-carrying ability, expressed in megawatts or megavolt-amperes, of generation, transmission, or other electrical equipment.

capacity commitment period - The one-year period from June 1 through May 31 of the following year for which Forward Capacity Market obligations are assumed and payments are made; same as a power year.

capacity factor - The ratio of the electrical energy a generating unit produced for a certain period of time to the electrical energy it could have produced at full operation during the same period.

capacity market - A market where generators receive compensation for investing in generating capacity. Load-serving entities, the market participants that secure electric energy, transmission service, and related services to serve the demand of their customers, make capacity payments to generators to ensure the long-term availability of sufficient generation capacity for the reliable operation of the bulk power grid.

capacity zone - To be determined before each Forward Capacity Auction, each export-constrained zone and any import constrained zone for which the amount of capacity projected to be installed in a load zone that is less than that load zone's forecasted local sourcing requirement. In addition, adjacent load zones that are neither export-constrained or import-constrained are treated as a single capacity zone.

cascading outage - The uncontrolled successive loss of bulk electric system facilities triggered by an incident (or condition) at any location on the system, which results in the interruption of electric service that cannot be restrained from spreading beyond a predetermined area. (Also see interconnection-reliability operating limit.)

claim 10 - The generation output level, expressed in megawatts, that a generator can reach from an off-line state within 10 minutes after receiving a dispatch instruction from ISO. This value is required as part of the generator's offer data and is used by ISO New England to evaluate the generator's contribution towards meeting operating- and replacement-reserve requirements.

Claim 30 - The generation output level, expressed in megawatts, that a generator can reach from an off-line state in 30 minutes after receiving a dispatch instruction from ISO. This value is required as part of the generator's offer data and is used by ISO New England to evaluate the generator's contribution towards meeting the New England Control Area's operating and replacement reserve requirements.

claimed capability - A generator's maximum output level as demonstrated to ISO.

cleared - In a market, when the quantity supplied (offered) has been matched to the quantity demanded (bid), the amount to be bought and sold has been determined, and settlement between buyers and sellers is possible.

coincident peak load - The highest value of the sum of all loads at one specific time in a particular geographic area. It is sometimes measured instantaneously and other times as the highest integrated hourly value.

combined cycle (CC) - A technology that produces electricity from otherwise lost waste heat from a combustion turbine, which increases the unit's efficiency for generating electricity.

commitment period - see capacity commitment period. Also, for the Day-Ahead and Real-Time Energy Markets, a period of continuous operation used to determine eligibility for NCPC credit.

congestion - A condition that arises on the transmission system when one or more restrictions prevents the economic dispatch of electric energy from serving load.

congestion component - The part of the nodal price that reflects the marginal cost of congestion at a given node or external node relative to the reference node.

constraint - Any transmission facility (or facilities) that operate at or over its limit (e.g., thermal limit, stability limit, or voltage limit).

contingency - The unplanned disconnection of a power system element, such as a transmission facility or a generator, from the electricity grid.

control area - See Balancing Authority Area.

Control Performance Standard - A reliability standard that sets the limits of a Balancing Authority's area control error over a specified time period.

cost of new entry (CONE) - as a concept, the price of capacity in $/kw-month that is needed to attract sufficient new capacity. It is determined using clearing prices in Forward Capacity Auctions as described in the Market Rule.

customer of ISO New England - An entity that "does business" with ISO New England, such as a Transmission Customer or Market Participant.



  Copyright ©2014 ISO New England Inc.