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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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.

Large load

Historically refers to industrial facilities with high electrical demand. They had long interconnection timelines that allowed for more study time under traditional planning processes. Currently, emerging large loads include cryptocurrency mining, data centers (conventional and artificial intelligence), oil field loads, and hydrogen production facilities. Many have a shorter timeline to interconnect (months vs. years) to the grid. In addition to these rapid timelines, some emerging large loads introduce new challenges to grid operators like rapid demand fluctuations and increased voltage sensitivity.

Load

The amount of power or electricity consumed by a device or system at a given time. It’s the demand placed on an energy source, like a power grid or a battery, by the connected electrical equipment.

Load growth

The increase in the demand for electricity over time. It signifies the rising need for power from various sectors, including residential, commercial, and industrial, and can be driven by factors like population increases, economic development, and the adoption of new technologies like electric vehicles and data centers.

Load shed

A controlled process where a utility company reduces or shuts off power supply to certain areas or customers to balance demand with available supply, preventing a complete system failure. It’s a last-resort measure to maintain grid stability when demand exceeds supply or when there are issues with power generation or transmission.

Locational Marginal Price (LMP)

A way for wholesale electric energy prices to reflect the value of electric energy at different locations, accounting for the patterns of load, generation, and the physical limits of the transmission system.

Loss of Load Expectation (LOLE)

Analysis is typically performed on a system to determine the amount of capacity that needs to be installed to meet the desired reliability target, commonly expressed as an expected value, or LOLE of 0.1 days/year.

MISO

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

Queue

(see: Interconnection Queue)

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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