Grid Glossary

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Critical Issue Fast Path (CIFP)

An accelerated stakeholder process used in PJM Interconnection to resolve urgent, contentious, and time-sensitive issues that cannot be resolved through the normal stakeholder process. The process involves several stages of discussion and proposal development, culminating in a submission to the Federal Energy Regulatory Commission (FERC) for approval. The CIFP process has been used in recent years to discuss large load additions (2025) and resource adequacy (2023).

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Effective Load Carrying Capability (ELCC)

Measurement used to calculate how much an energy resource–such as a wind farm or solar array–contributes to the overall reliability of the grid. It assesses the resource’s ability to meet electricity demand, particularly during peak usage periods, and is especially useful for variable renewable energy sources whose output depends on factors like weather conditions. 

TRENDING TERM

Disturbance

Refers to any unwanted or unplanned electrical event that interferes with the normal operation of the electrical grid. These can manifest in power outages, surges, and other events, and can originate from various sources within the electrical grid, such as loss of a large generating unit or another grid asset, such as a transmission line or transformer.

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202(c) Order

An emergency order issued by the United States Department of Energy (DOE) under Section 202(c) of the Federal Power Act. It allows the Secretary of Energy to temporarily order connections of facilities and the generation, delivery, or transmission of electricity to best meet an emergency caused by war, a sudden increase in demand, or a shortage of energy or facilities. These temporary orders can also exempt power plants from federal, state, or local environmental rules and have historically been used to prevent outages during severe weather events or supply shortfalls.

Active power

Also known as real or true power, is the portion of electrical power that does useful work in a circuit, such as generating heat, light, or mechanical energy. (see related: reactive power)

Advance Notice of Proposed Rulemaking (ANOPR)

A preliminary document used by government agencies to solicit public feedback on potential new rules or reforms before they are officially proposed. It outlines initial ideas, asks specific questions, and serves as the first step in a larger regulatory process. The acronym is frequently used by the Federal Energy Regulatory Commission (FERC). It precedes a formal Notice of Proposed Rulemaking (NOPR) and allows agencies to gauge public opinion and gather information to develop a more informed proposal.

Ancillary services

(see also: Essential reliability services) – Supplementary services essential for maintaining the reliable operation and stability of the electrical grid beyond the basic generation and transmission of energy. They are “behind-the-scenes” services that include real-time balancing of electricity supply and demand, maintaining voltage levels, and providing the capability to restart the grid after a widespread outage (black start). 

Automatic Generation Control (AGC)

Is an automated system that continuously monitors the electrical network and adjusts the power output of multiple generators. Its primary functions are to maintain system frequency (60 Hz in United States), in response to changes in the power demand, or load.

Demand-response programs

These incentivize customers to reduce, increase, or shift their electricity consumption in response to price spikes or grid reliability signals. Most programs encourage utility customers primarily through price incentives to shift electricity consumption from hours of high demand (relative to energy supply) to hours when energy supply is plentiful (relative to demand).

Demand-side solutions

These encompass strategies and programs designed to influence electricity consumption patterns on the customer side of the meter. These initiatives aim to moderate electricity demand through methods such as financial incentives for energy conservation and energy efficiency measures, like improved insulation or the adoption of energy-efficient appliances. 

Dispatchable energy

Refers to electricity generation resources that power grid operators can control and adjust on demand to meet changing electricity needs. These include nuclear, hydropower, battery storage, and thermal power plants.

Distributed Energy Sources (DER)

Small-scale energy generation and storage technologies located near the point where the energy is used, rather than at a centralized power plant. These resources–such as solar microgrids, rooftop solar, and battery storage–can be used to enhance or replace traditional energy sources and can operate independently or be connected to the main grid. 

Disturbance

Refers to any unwanted or unplanned electrical event that interferes with the normal operation of the electrical grid. These can manifest in power outages, surges, and other events, and can originate from various sources within the electrical grid, such as loss of a large generating unit or another grid asset, such as a transmission line or transformer.

Disturbance ride-through

The ability of a piece of electrical equipment to stay connected to the grid through a short-term disturbance, thus helping keep the grid stable through the event. Inverter-based resources, such as photovoltaic solar arrays, wind turbines, and battery storage, can provide disturbance ride-through services, but require specific design of their control system to do so.

Docket

In energy regulation, it is a formal proceeding or official record initiated by a regulatory body (such as a Public Utilities Commission or the Federal Energy Regulatory Commission (FERC)) to address a specific issue or project. It serves as a repository for all submitted documents, evidence, and public comments.

Duck curve

A visual representation of how solar power generation impacts the daily electricity demand curve, particularly in regions with high solar adoption like California. It depicts a dip in net electricity demand during midday due to solar generation, followed by a steep increase in the evening as solar output decreases and demand peaks.

Hydrogen

Fuel cell that carries energy generated from another source. It can be used in fuel cells to generate electricity with water as the only byproduct, or it can be burned for heat. Hydrogen can be produced from a variety of sources–renewable energy such as solar or wind, or gas plants, nuclear, and other energy sources–which dictate whether it can be considered “clean” or not.

MISO

Midcontinent Independent System Operator, serves northern Midwest, southeast, and parts of Canada

Offshore wind

Wind turbines erected in bodies of water that harness the power of wind, converting it into electricity that is then transmitted to the mainland to power homes and businesses. Offshore wind farms are considered a renewable energy source.

Operational reliability

The real-time balancing of energy supply and demand to maintain frequency and voltage within safe operating limits. It is the shorter-term dimension of reliability and requires regular monitoring and control of the entire grid. It includes the ability to quickly respond to sudden changes, like the loss of a major power plant or transmission line, and to handle normal variations in supply and demand.

Reactive power

Power that does not perform useful work but is used to establish and maintain electromagnetic fields that are needed to generate, transmit, and convert electric power in the alternating current network. A shortage of reactive power can cause voltage to decline. (See also: voltage support)

Reliability

A characteristic of the whole electricity system to describe its ability to consistently deliver electricity to consumers without interruption, even through grid disturbances. Reliability comes down to having sufficient generating resources to meet demand and a functional operational grid system.

Reliability must-run (RMR) contract

An agreement initiated by an RTO or ISO with a power plant, keeping it in operation temporarily for reliability purposes.

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