Smart Grid Definitions of Functions
Function Definition
Fault current limiting can be achieved through sensors, communications, information
processing, and actuators that allow the utility to use a higher degree of network
Fault Current coordination to reconfigure the system to prevent fault currents from exceeding
Limiting damaging levels. Fault current limiting can also be achieved through the
implementation of special stand alone devices known as Fault Current Limiters (FCLs)
which act to automatically limit high through currents that occur during faults.
Wide Area Wide area monitoring and visualization requires time synchronized sensors,
Monitoring, communications, and information processing that make it possible for the condition
Visualization, & of the bulk power system to be observed and understood in real‐time so that
Control protective, preventative, or corrective action can be taken.
Dynamic Dynamic capability rating can be achieved through real‐time determination of an
Capability element’s (e.g., line, transformer etc.) ability to carry load based on electrical and
Rating environmental conditions.
Flow control requires techniques that are applied at transmission and distribution
levels to influence the path that power (real & reactive) travels. This functionality is
Power Flow
enabled by tools such as flexible AC transmission systems (FACTS), phase angle
Control
regulating transformers (PARs), series capacitors, and very low impedance
superconductors.
Adaptive protection uses adjustable protective relay settings (e.g., current, voltage,
Adaptive feeders, and equipment) that can change in real time based on signals from local
Protection sensors or a central control system. This is particularly useful for feeder transfers and
two‐way power flow issues associated with high DER penetration.
Automated feeder and line switching is realized through automatic isolation and
Automated reconfiguration of faulted segments of distribution feeders or transmission lines via
Feeder and Line sensors, controls, switches, and communications systems. These devices can operate
Switching autonomously in response to local events or in response to signals from a central
control system.
Automated islanding and reconnection is achieved by automated separation and
subsequent reconnection (autonomous synchronization) of an independently
Automated
operated portion of the T&D system (i.e., microgrid) from the interconnected electric
Islanding and
grid. A microgrid is an integrated energy system consisting of interconnected loads
Reconnection
and distributed energy resources which, as an integrated system, can operate in
parallel with the grid or as an island.
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Smart Grid Definitions of Functions
Function Definition
Automated voltage and VAR control requires coordinated operation of reactive
Automated power resources such as capacitor banks, voltage regulators, transformer load‐tap
Voltage and changers, and distributed generation (DG) with sensors, controls, and
VAR Control communications systems. These devices could operate autonomously in response to
local events or in response to signals from a central control system.
Diagnosis and notification of equipment condition is defined as on‐line monitoring
Diagnosis & and analysis of equipment, its performance, and operating environment in order to
Notification of detect abnormal conditions (e.g., high number of equipment operations,
Equipment temperature, or vibration). Asset managers and operations personnel can then be
Condition automatically notified to respond to conditions that increase the probability of
equipment failure.
Enhanced fault protection requires higher precision and greater discrimination of
fault location and type with coordinated measurement among multiple devices. For
distribution applications, these systems will detect and isolate faults without
full‐power re‐closing, reducing the frequency of through‐fault currents. Using high
Enhanced Fault resolution sensors and fault signatures, these systems can better detect high
Protection impedance faults. For transmission applications, these systems will employ high
speed communications between multiple elements (e.g., stations) to protect entire
regions, rather than just single elements. They will also use the latest digital
techniques to advance beyond conventional impedance relaying of transmission
lines.
This function provides real‐time measurement of customer consumption and
Real-time Load
management of load through Advanced Metering Infrastructure (AMI) systems
Measurement
(smart meters, two‐way communications) and embedded appliance controllers that
and
help customers make informed energy use decisions via real‐time price signals,
Management
time‐of‐use (TOU) rates, and service options.
Real‐time load transfer is achieved through real‐time feeder reconfiguration and
Real-time Load
optimization to relieve load on equipment, improve asset utilization, improve
Transfer
distribution system efficiency, and enhance system performance.
Customer electricity use optimization is possible if customers are provided with
Customer
information to make educated decisions about their electricity use. Customers could
Electricity Use
be able to optimize toward multiple goals such as cost, reliability, convenience, and
Optimization
environmental impact.
