Technology beginning with D

Smart Grid Technology
Click one of the letters above to go to the page of all terms beginning with that letter.
Deferred Distribution Capacity Investments

As with the transmission system, reducing the load and stress on distribution elements increases asset utilization and reduces the potential need for upgrades. Closer monitoring and load management on distribution feeders could potentially extend the time before upgrades or capacity additions are required.

Deferred Generation Capacity Investments

Utilities and grid operators ensure that generation capacity can serve the maximum amount of load that planning and operations forecasts indicate. The trouble is, this capacity is only required for very short periods each year, when demand peaks. Reducing peak demand and flattening the load curve should reduce the generation capacity required to service load and lead to cheaper electricity for customers.

Deferred Transmission Capacity Investments

Reducing the load and stress on transmission elements increases asset utilization and reduces the potential need for upgrades. Closer monitoring, rerouting power flow, and reducing fault current could enable utilities to defer upgrades on lines and transformers.

Delayed Fault Clearing

Fault clearing consistent with correct operation of a breaker failure protection system and its associated breakers, or of a backup protection system with an intentional time delay.


The rate at which electric energy is delivered to or by a system or part of a system, generally expressed in kilowatts or megawatts, at a given instant or averaged over any designated interval of time., The rate at which energy is being used by the customer.

Demand Side Management

The term for all activities or programs undertaken by Load-Serving Entity or its customers to influence the amount or timing of electricity they use.

Diagnosis & Notification Of Equipment Condition

Diagnosis and notification of equipment condition is defined as on-line monitoring and analysis of equipment, its performance, and operating environment in order to detect abnormal conditions (e.g., high number of equipment operations, temperature, or vibration). Asset managers and operations personnel can then be automatically notified to respond to conditions that increase the probability of equipment failure.

Direct Control Load Management

Demand-Side Management that is under the direct control of the system operator. DCLM may control the electric supply to individual appliances or equipment on customer premises. DCLM as defined here does not include Interruptible Demand.

Direct Load Control Device

A remotely controllable switch that can turn power to a load or appliance on or off. Such a device could also be used to regulate the amount of power that a load can consume. Direct load control devices can be operated by a utility or third party energy provider to reduce a customer's energy demand at certain times.

Dispersed Load By Substations

Substation load information configured to represent a system for power flow or system dynamics modeling purposes, or both.

Distributed Energy Resource

A device that produces electricity, and is connected to the electrical system, either "behind the meter" in the customer's premise, or on the utility's primary distribution system. A Distributed Energy Resource (DER) can utilize a variety of energy inputs including, but not limited to, liquid petroleum fuels, biofuels, natural gas, solar, wind, and geothermal. Electricity storage devices can also be classified as DERs.

Distributed Energy Resource Interface

A device through which a distributed energy resource (DER) is connected to the electrical system. The interface may include power conversion, communications and control systems that can manage the output and performance of the DER, and coordinate the DER's operation with other smart grid systems.

Distribution Automation

Distribution Automation (DA) is a family of technologies including sensors, processors, communication networks and switches that can perform a number of distribution system functions depending on how they are implemented. Over the last 20 years, utilities have been applying DA to improve reliability, service quality and operational efficiency. More recently, DA is being applied to perform automatic switching, reactive power compensation coordination and other feeder operations/control.

Distribution Automation Communications Network

A communications network or networks designed to deliver control signals and information between distribution automation devices, and between these devices and utility grid control systems. These networks can utilize wired or wireless connections, and can be utility-owned or provided as services by a third party.

Distribution Factor

The portion of an Interchange Transaction, typically expressed in per unit that flows across a transmission facility (Flowgate).

Distribution Management System

A Distribution Management System (DMS) is a utility IT system capable of collecting, organizing, displaying and analyzing real-time distribution system information. A DMS can help plan and execute distribution system operations to increase system efficiency, optimize power flows, and prevent overloads. A DMS can interface with other applications such as geographic information systems (GIS), outage management systems (OMS), and customer information systems (CIS) for a full view of distribution operations.

Distribution Provider

Provides and operates the 'wires' between the transmission system and the end-use customer. For those end-use customers who are served at transmission voltages, the Transmission Owner also serves as the Distribution Provider. Thus, the Distribution Provider is not defined by a specific voltage, but rather as performing the Distribution function at any voltage.


An unplanned event that produces an abnormal system condition., Any perturbation to the electric system., The unexpected change in ACE that is caused by the sudden failure of generation or interruption of load.

Disturbance Control Standard

The reliability standard that sets the time limit following a Disturbance within which a Balancing Authority must return its Area Control Error to within a specified range.

Disturbance Monitoring Equipment

Devices capable of monitoring and recording system data pertaining to a Disturbance. These include: Sequence of event recorders, Fault recorders: This may include protective relays, Dynamic Disturbance Recorders (DDRs), which record incidents that portray power system behavior during dynamic events such as low-frequency (0.1 Hz - 3 Hz) oscillations and abnormal frequency or voltage excursions. PMUs and any other equipment that meets the functional requirements of DMEs may qualify as DMEs.

Dynamic Capability Rating

Dynamic capability rating can be achieved through real?time determination of an element's (e.g., line, transformer etc.) ability to carry load based on electrical and environmental conditions.

Dynamic Capability Rating System

Dynamic capability rating adjusts the thermal rating of power equipment based on factors such as air temperature, wind speed, and solar radiation to reflect actual operating conditions. These systems are primarily used on high capacity or critical power system elements such as transmission lines and large power transformers.

Dynamic Interchange Schedule Or Dynamic Schedule

A telemetered reading or value that is updated in real time and used as a schedule in the AGC/ACE equation and the integrated value of which is treated as a schedule for interchange accounting purposes. Commonly used for scheduling jointly owned generation to or from another Balancing Authority Area.

Dynamic Pricing Program

Dynamic pricing refers to the family of rates that offer customers time-varying electricity prices on a day-ahead or real-time basis.

Dynamic Transfer

The provision of the real-time monitoring, telemetering, computer software, hardware, communications, engineering, energy accounting (including inadvertent interchange), and administration required to electronically move all or a portion of the real energy services associated with a generator or load out of one Balancing Authority Area into another. Economic Dispatch The allocation of demand to individual generating units on line to effect the most economical production of electricity.