Grid Glossary

TRENDING TERM

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).

TRENDING TERM

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.

Baseload

The minimum amount of electricity that a utility must provide to meet the consistent, ongoing needs of its customers. Historically, this steady demand was met by large power plants (like coal or nuclear) that ran continuously. Today, with more renewable energy, this minimum demand can be met by a flexible mix of various power sources, rather than relying solely on specific “baseload plants”.

  • Baseload capacity:  The generating equipment normally operated to serve loads on an around-the-clock basis.
  • Baseload plant:  A plant, usually housing high-efficiency steam-electric units, which produces electricity at an essentially constant rate and runs continuously. 
Battery Energy Storage System (BESS)

A technology that stores electrical energy in rechargeable batteries for later use. Batteries help stabilize the grid, manage energy demand, and increase the use of renewable energy.

Behind-the-meter

Any energy resource that provides energy directly to a home or business without passing through a utility company’s meter. Examples include rooftop solar and microgrids.

Federal Energy Regulatory Commission (FERC)

An independent agency that regulates the interstate transmission of natural gas, oil, and electricity. FERC also regulates natural gas and hydropower projects.

Federal Power Act

A United States law primarily regulating the interstate transmission and sale of electricity and the development of hydroelectric power. It was responsible for creating the body now known as FERC. It was created in 1920 and has been amended several times since. 

Firming requirements

Measures taken to ensure backup power, particularly of renewable energy, such as solar and wind generators. These requirements may require battery storage, ancillary services, or backup generation, such as an added gas plant to produce energy when a solar or wind plant does not.

Frequency

Electricity is supplied to homes and businesses in the United States in the form of alternating current, and frequency is the rate at which an alternating current changes direction, as measured in hertz (Hz). Across the power grid there is a consistent frequency which in the United States is 60 Hz. 

Frequency regulation or response

The ability of the grid to react to a change in

the frequency to bring it back to the normal operating frequency, which is 60 Hz in the United States

  • Inertial response refers to the injection of stored energy, such as battery energy, into the electricity grid to slow down a decline in frequency. 
  • Primary frequency response – The first line of defense against frequency fluctuations that could destabilize the grid. It takes the form of immediate, automatic adjustments in power output by generators and loads in response to frequency deviations in the electric grid.
  • Fast frequency response consists of the combined inertial response and primary frequency response. It injects energy in the seconds immediately following a disturbance to slow frequency decline and establishes the minimum frequency (called the nadir).
  • Secondary frequency response works on a slightly longer time frame than primary frequency response, on the order of 5-15 minutes. It maintains grid frequency and allows for scheduled energy transfers between balancing authorities, which include utilities, regional transmission operators, and other grid management entities.
National Association of Regulatory Utility Commissioners (NARUC)

A non-profit organization that represents state public service commissions, which regulate essential utility services like energy, telecommunications, and water. Its stated aim is to improve the quality and effectiveness of public utility regulation. It has eight committees:

  1. Consumer Affairs
  2. Critical Infrastructure
  3. Electricity
  4. Energy Resources & Environment
  5. Gas
  6. International Relations
  7. Telecommunications
  8. Water

It also has a task force focused on Innovation.

NERC

Non-profit organization that operates to assure the effective and efficient reduction of risks to the reliability and security of the grid. It oversees six regional reliability entities and encompasses all of the interconnected power systems of Canada and the contiguous United States, as well as a portion of the Mexican state of Baja California. Its responsibilities include working with all stakeholders to develop standards for power system operation, monitoring and enforcing compliance with those standards, assessing resource adequacy, and providing educational and training resources as part of an accreditation program. NERC also investigates and analyzes the causes of significant power system disturbances in order to help prevent future events and produces reports about the near and long-term reliability forecast.

Notice of Proposed Rulemaking (NOPR)

A document used by government agencies to announce a potential new rule or amendment to an existing one. This is an official part of the law-making process, allowing public comment before the rule is finalized. The acronym is frequently used by the Federal Energy Regulatory Commission (FERC).

NREL

A government-owned, contractor-operated facility, funded and overseen by the United States Department of Energy’s (DOE) Office of Energy Efficiency and Renewable Energy (EERE). It specializes in the research and development of renewable energy, energy efficiency, energy systems integration, and sustainable transportation.

NYISO

New York ISO

Queue

(see: Interconnection Queue)

Virtual Power Plant

A network of distributed energy resources—like rooftop solar panels, electric vehicle chargers, and smart water heaters—that work together to balance energy supply and demand on a large scale. They are usually run by local utility companies that oversee this balancing act.

Voltage

Often described as the “pressure” that pushes electric current through a circuit. It’s measured in volts (V) and is essentially the energy per unit charge. Think of it like water pressure: the higher the voltage, the greater the “push” on electrons, and the more current can flow.

Maintaining stable voltage on the grid  is critical to keeping the lights on and avoiding equipment damage. Voltage is not consistent across the grid, though it is locally constant, with higher voltages used for longer transmission lines and lower voltages used at the distribution level.

  • Voltage support – The ability of a power system to maintain stable voltage levels within a desired range, even during fluctuations or disturbances. It’s crucial for ensuring a reliable electricity supply and preventing equipment damage. Generally, it is achieved by a grid maintaining reactive power via generating units or other equipment absorbing or adding reactive power.

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