Grid Glossary

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Inverter-Based Resources (IBR)

A power generation or storage device (such as a battery) that connects to the electrical grid through an inverter, a power electronic device that converts direct current (DC) to alternating current (AC). These resources, including solar photovoltaic (PV) systems, wind turbines, and battery energy storage systems, are increasingly important for grid stability.

ISO-NE

ISO New England

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.

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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