Technology beginning with A

Smart Grid Technology
Click one of the letters above to go to the page of all terms beginning with that letter.
Adaptive Protection

The use of adjustable protective relay settings (e.g., current, voltage, feeders, and equipment) that can change in real time based on signals from local sensors or a central control system. This is particularly useful for feeder transfers and two-way power flow issues associated with high Distributed Energy Resource (DER) penetration.


The ability of the electric system to supply the aggregate electrical demand and energy requirements of the end-use customers at all times, taking into account scheduled and reasonably expected unscheduled outages of system elements.

Adjacent Balancing Authority

A Balancing Authority Area that is interconnected another Balancing Authority Area either directly or via a multi-party agreement or transmission tariff.

Advanced Interrupting Switch

A distribution switch with built-in technology that can detect and interrupt faults more quickly and precisely. Such a device may rely on advanced fault detection techniques, and may not require full-line reclosing and sectionalizing to isolate faults.

Advanced Metering Infrastructure (AMI) / Smart Meters

Electricity meters that use two-way communication to collect electricity usage and related information from customers and to deliver information to customers.

Advanced Transmission Applications

Software that utilizes synchrophasor information for real-time grid operations or planning and off-line analysis. These applications are aimed at providing wide-area situational awareness, grid monitoring, and detailed power system analysis and the improvement or validation of power system models.

Adverse Reliability Impact

The impact of an event that results in frequency-related instability; unplanned tripping of load or generation; or uncontrolled separation or cascading outages that affects a widespread area of the Interconnection.

Altitude Correction Factor

A multiplier applied to specify distances, which adjusts the distances to account for the change in relative air density (RAD) due to altitude from the RAD used to determine the specified distance. Altitude correction factors apply to both minimum worker approach distances and to minimum vegetation clearance distances.

Ancillary Service

Those services that are necessary to support the transmission of capacity and energy from resources to loads while maintaining reliable operation of the Transmission Service Provider's transmission system in accordance with good utility practice. (From FERC order 888-A.)

Ancillary Services Revenue

Revenue generated through the competitive ancillary services market for spinning reserves or frequency regulation.

Anti-Aliasing Filter

An analog filter installed at a metering point to remove the high frequency components of the signal over the AGC sample period.

Area Control Error

The instantaneous difference between a Balancing Authority's net actual and scheduled interchange, taking into account the effects of Frequency Bias and correction for meter error.

Arranged Interchange

The state where the Interchange Authority has received the Interchange information (initial or revised).

Automated Capacitors

Automated Capacitors can increase the voltage on a distribution circuit by providing reactive power (often referred to as volt-amperes-reactive or VArs). Capacitor banks are switched in discrete steps, either manually, or in response to the voltage at the location where they are connected. Typically, distribution capacitor banks are switched in a single step.

Automated Distribution Circuit Switches

Distribution circuit switches operate automatically in response to control signals from local sensors, distribution automation systems, or grid control systems. Such switches can be installed as automated devices. Existing equipment can be retrofitted with controls and communications. These switches can be opened or closed to help locate a short circuit, or taken out of service for maintenance. When used in combination, these switches can reroute power from other substations or nearby distribution circuits.

Automated Feeder And Line Switching

Automated feeder and line switching is realized through automatic isolation and reconfiguration of faulted segments of distribution feeders or transmission lines via sensors, controls, switches, and communications systems. These devices can operate autonomously in response to local events or in response to signals from a central control system.

Automated Islanding And Reconnection

Automated Islanding and Reconnection Automated islanding and reconnection is achieved by automated separation and subsequent reconnection (autonomous synchronization) of an independently operated portion of the T&D system (i.e., microgrid) from the interconnected electric grid. A microgrid is an integrated energy system consisting of interconnected loads and distributed energy resources which, as an integrated system, can operate in parallel with the grid or as an island.

Automated Voltage And Var Control

Automated voltage and VAR control requires coordinated operation of reactive power resources such as capacitor banks, voltage regulators, transformer load-tap changers, and distributed generation (DG) with sensors, controls, and communications systems. These devices could operate autonomously in response to local events or in response to signals from a central control system.

Automated Voltage Regulators

Voltage regulators are transformers that can increase or decrease the voltage on a distribution circuit to help keep the voltage within a pre-determined band. Unlike capacitor banks, voltage regulators cannot adjust power factor. They typically monitor the voltage at the location where they are connected, comparing it to a programmed set point. If the voltage deviates too far from the set point, the voltage regulator can adjust its output voltage by moving the tap on the secondary side up or down.

Automatic Generation Control

Equipment that automatically adjusts generation in a Balancing Authority Area from a central location to maintain the Balancing Authority's interchange schedule plus Frequency Bias. AGC may also accommodate automatic inadvertent payback and time error correction.

Available Transfer Capability

A measure of the transfer capability remaining in the physical transmission network for further commercial activity over and above already committed uses. It is defined as Total Transfer Capability less existing transmission commitments (including retail customer service), less a Capacity Benefit Margin, less a Transmission Reliability Margin.