A-C | D-E | F-I | L-N| O-Q | R | S-Z | Acronyms
offer - A request to provide generation, measured in megawatts, at a specific location.
off-peak hours - In New England, weekday hours between 11:00 p.m. and 7:00 a.m. and all day Saturdays, Sundays, and holidays. See peak hours.
one day in 10 years or "1 in 10" - The Northeast Power Coordinating Council (NPCC) resource reliability criterion that states that the probability of disconnecting firm load as a result of a resource deficiency can be no greater than one day in 10 years.
on-peak hours - From 7:00 a.m. through 11:00 p.m. on all nonholiday weekdays; same as peak hours.
operable capacity analysis - An estimate of the availability of a system's net capacity under specific scenarios and load conditions. The results are in the form of operable capacity margins, which show either an expected system surplus or a deficiency in meeting the conditions.
operable capacity margin - The amount of resources that must be operational to meet peak demand plus operating-reserve requirements.
operating day - The calendar day, beginning at midnight and ending at 2400 hours, for which transactions in the New England markets are scheduled.
operating reserve - The megawatt capability of a power system greater than system demand, which is required for providing frequency regulation, correcting load forecasting errors, and handling forced outages, drawn from spinning and nonspinning sources of power. Also, the synchronized or nonsynchronized reserves that may be used to recover from a contingency.
outage - When a facility or piece of equipment goes off line. See forced outage, planned outage, scheduled outage, and unplanned outage.
out of economic-merit order (out of merit) - Capacity (in megawatts) that is more expensive than the marginal, price-setting, supply offer.
out-of-market compensation - Payments to resources outside the electricity market clearing processes, such as Reliability Agreements.
out-of-merit cost - A payment to a generator for operating when it is more expensive for it to do so than the price-setting generator.
ownership share - For settlement purposes, a right or obligation for a percentage share of all credits or charges associated with a generating resource at a node where the resource is interconnected to the New England transmission system.
participant - See market participant.
peak hours - In New England, the hours between 7:00 a.m. and 11:00 pm on nonholiday weekdays; same as on-peak hours.
peak-load generating unit - A generating unit that is used to meet system requirements during peak-load periods when the demand on the system is the greatest. These units typically operate at a relatively high cost and run when the price of electric energy is high.
planned outage - The planned inoperability of a generator, generally to perform maintenance.
Planning Authority (PA) - An entity responsible for coordinating and integrating transmission facility and service plans, resource plans, and protection systems. The ISO has registered with NERC as a PA and is responsible for complying with NERC standards applicable to a PA.
posturing - Instances in which generators are directed to operate below their economic dispatch point for reliability reasons.
power - See electric power.
power market - The buying and selling of electricity. See electric energy market, electricity market, and wholesale electric energy market.
power system - The elements of an electrical system, including generation units, transmission lines, distribution lines, substations, and other equipment. See bulk power system.
power year - A year that runs from June 1 through May 31 of the following year used to calculate the Installed Capacity Requirement (ICR) for the New England Control Area. The ISO calculates the ICR for each upcoming power year through the capacity commitment period associated with a Forward Capacity Auction. Each power year is the same as a capacity commitment period.
price quantity pairs - Price-sensitive bid-block information that consists of a quantity of megawatts and the available dollar price for the megawatts.
price response - The reduction of electricity consumption in response to a price signal.
price-sensitive demand - The purchase of electric energy up to a certain price.
price separation - in a locational market, when different clearing prices exist at different locations. In an energy market, price separation is due to transmission constraints and congestion. In the Forward Capacity Auction, when capacity zones experience a difference in price as a result of the quantity of capacity remaining in each capacity zone as the descending clock drops in price.
price-taker - A market participant whose buying and selling actions do not affect the market price; a generator that has offered into the market at zero or has self-scheduled, is willing to operate at any price, and is not eligible to set clearing prices.
pricing node (Pnode) - A location (external interface, load node, individual unit node, load zone, and the Hub, which are collections of pnodes) where ISO New England calculates and publishes prices for electric energy.
prime mover - The motive force that drives an electric generator, such as a water or steam turbine, which converts thermal or hydraulic energy into mechanical energy that will in turn be converted to electrical energy. Falling water, heat, wind, nuclear, fossil fuels (oil, natural gas, coal), biomass, and the sun are fuels used to drive prime movers.
pumped storage - a generating facility where water is pumped up to a storage pond, during periods of low demand and lower cost, to produce electricity during periods of high demand and higher prices.
quick-start resource - See fast-start resource.