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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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.

Economic dispatch

The mechanism for choosing the lowest cost energy option that meets energy needs, which gives cheaper renewable energy and battery storage an edge. 

  • Uneconomic dispatch – when a grid operator/utility chooses a higher-priced energy option, or above market-rate source, to meet electricity needs. This has emerged as a significant problem in areas where United States utilities are operating coal plants that can’t compete on cost with gas-fueled facilities and renewables. This practice allows utilities to continue to collect the costs of fuel and operations from customers to pay off their investment in the power plant.
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. 

Energy efficiency

Measures that reduce electricity use in a home or business. These measures include replacing inefficient heating and air conditioners with heat pumps, adding attic insulation, and sealing ducts and foundation, walls, roof, windows, and doors of buildings. It also includes replacing energy-intensive appliances with more efficient ones. These measures can provide energy savings, improve comfort, and increase property values.

Energy-only interconnection approaches

Connecting new generation to the grid with minimal transmission upgrades and managing impacts through operational strategies rather than extensive upfront infrastructure investments. This approach, often referred to as “connect and manage,” prioritizes adding generation capacity quickly while relying on the grid operator to manage any resulting operational constraints. It requires new resources to risk curtailment (where the generator is asked to stop supplying power to the grid when supply is too high). The process has allowed Texas’ ERCOT to connect record numbers of new clean projects in the last several years significantly faster than other regions. 

ERCOT

The Electric Reliability Council of Texas serves as an independent system operator (ISO), managing the flow of electrical power over transmission infrastructure in the state of Texas.

Essential reliability services

A combination of automated and manual controls grid operators adjust to maintain grid reliability by ensuring a balance between supply (generation) and demand (load). They generally consist of three main aspects:

  • frequency response – short-term adjustments to maintain the grid’s oscillations at 60 hz)
  • balancing – related to frequency response but on longer time frames, to, for e.g., plan for energy resource outages due to maintenance, and 
  • voltage control – involves magnetic waves to allow for the movement of watts of energy
Queue

(see: Interconnection Queue)

Thermal source

A type of power station in which the heat energy generated from various fuel sources (e.g., coal, natural gas, nuclear fuel, etc.) is converted to electrical energy.

Transfer capacity

The maximum amount of electrical power that can be reliably moved from one geographic region of the power grid to another, essentially indicating the ability of the transmission lines connecting those regions to transport electricity between them without causing instability or exceeding safety limits. It’s a crucial concept for ensuring the safe and efficient operation of the power system, particularly in the context of electricity markets and grid planning.

Transformers

Equipment used to increase and decrease voltages at grid interfaces.

Transmission

The process (and infrastructure) of moving large amounts of electrical power over long distances from where it is generated, like a power plant, to substations closer to consumers.

Watts

Measure of the rate of energy transfer over a unit of time, with one watt equal to one joule (J) per second.

Wind power

A form of renewable energy that uses the kinetic energy of wind to generate electricity. It involves capturing the wind’s energy through turbines, which then convert this mechanical energy into electricity. Modern wind power generation primarily relies on wind turbines, often grouped into wind farms, connected to the electrical grid.

Winter peaking

The increase in energy demand during the winter months, usually due to heating needs. This can lead to higher energy prices and bills for a number of reasons, including: 

  • Strained energy grid: The high demand can strain the energy grid, which can cause utilities to work harder to meet the need.
  • Seasonal rate adjustments: Many energy providers adjust rates based on seasonal demand.
  • Increased use of lighting: Shorter and darker winter days can lead to greater use of in-home lighting.

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