Glossary - s

For your convenience, this page contains an alphabetically organized list of terms, definitions and common acronyms used in the electric utility industry.

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Term/Acronym

Definition
SCADA Supervisory Control And Data Acquisition
SET Standard Electronic Transaction
SPP Southwest Power Pool
Sample Design The processes by which ERCOT determines the appropriate requirements for a sample of Customer Premises which requirements will be used to create a Load Profile.
Sample Size The number of data points (i.e. Customer Premises) in a particular sample.
Sampling The process of selecting a subset of a population of Customers that statistically represents the entire population.
Schedule Control Error The difference in the QSE's actual Resource output and its base power schedule plus instructed Ancillary Services.
Scheduling Process The process through which schedules for energy and Ancillary Services are submitted by QSEs to ERCOT as further described in Section 4, Scheduling.
Season Winter months are December, January, and February; Spring months are March, April, and May; Summer months are June, July, and August; Fall months are September, October, and November.
Segmentation The process of dividing a population into a number of sub-sets, according to certain parameters, for the purpose of creating Load Profiles for sub-sets of the population.
Segmentation Parameter The parameter chosen as the basis for Segmentation.
Self-Arranged Ancillary Service Resources used for Ancillary Services designated by a QSE for use by ERCOT for meeting the ERCOT allocated portion of the Ancillary Services Obligations of a QSE. These Resources may not be included in the ERCOT Ancillary Services market.
Service Address

The street address associated with an ESI-ID as recorded in the Registration Database. This address shall conform to United States Postal Service Publication 28.
Service Delivery Point The specific point on the TDSP's system where electricity flows from the TDSP to a Load.
Service Fee Schedule A listing of ERCOT fees and charges to Market Participants, posted on the Market Information System.
Service Filing A filing by a QSE to ERCOT as part of the QSE's certification process, as defined in Section 16, Qualification of Qualified Scheduling Entities and Registration of Market Participants.
Settlement Calendar As defined in Section 9.1.2, Settlement Calendar.
Settlement Interval The time period for which a Market Service is deployed and financially settled. For example, the currently defined settlement interval for the Balancing Energy Market Service is 15 minutes.
Settlement Invoice See Invoice
Settlement Meter Generation and end-use consumption meters used for allocation of ERCOT charges and wholesale and retail settlements.
Settlement Quality Meter Data Data that has been edited, validated, and is appropriate for ERCOT Settlement Agent to use for settlement and billing purposes.
Settlement Statement A statement issued by ERCOT reflecting a breakdown of administrative, miscellaneous, and market charges for the applicable Market Services, as further described in Section 9.2, Settlement Statement.
  • Initial Statement
    The first iteration of a Settlement Statement issued for a particular Operating Day, as further described in Section 9.2.1, Initial Statement
  • Final Statement
    The statement issued at the end of the forty-fifth (45th) calendar day following the Operating Day, as described in 9.2.2, Final Statements.
  • Resettlement Statement
    The statement using corrected settlement data, in accordance with Section 9.2.3, Resettlement Statement.
  • True-Up Statement
    The statement issued six (6) months following the Operating Day, as further described in Section 9.2.4, True-Up Statement.
Shadow Price The cost of an operation to effect a one (1) MW change in a constraint.
Shift Factor A measure of the flow of a unit injection of the power on the transmission element from a particular bus to a fixed reference bus.
  • Site Specific Shift Factor
    The actual Shift Factor for a particular bus.
  • Zonal Shift Factor
    The average Shift Factor for all busses in a particular zone.
Sign/Direction Terminology Conventions for Reactive Power
  • Generator
    Lagging power factor operating condition is when volt-ampere reactive (VAR) flow is out of the Generation Resource unit (overexcited generator) and into the transmission system and is considered to be positive (+) flow, i.e., in the same direction as megawatt power flow. The generator is producing megavolt-amperes reactive. Leading power factor operating condition means that VAR flow is into the Generation Resource unit (underexcited generator) and out of the transmission system and is considered to be negative (-) flow, i.e., in the opposite direction as megawatt power flow. The generator is absorbing megavolt-amperes reactive.
  • Transmission Line Terminal
    VAR flow out of the bus and into the line is considered to be positive (+) flow. VAR flow into the bus and out of the line is considered to be negative (-) flow.
  • Capacitor
    Produces reactive power (VAR source) for voltage control and causes the system power factor to move towards a leading condition.
  • Reactor
    Absorbs reactive power (VAR sink) for voltage control and causes the system power factor to move towards a lagging condition.
    • Supply Total supply scheduled by a QSE that is comprised of Energy Supply and Ancillary Services Supply where:

    • Energy Supply =
      Resources + energy purchases + energy imports; and
    • Ancillary Services Supply =
      Resources + Ancillary Services purchases (including purchases through ERCOT) + Ancillary Services imports
    Synchronous Condenser Unit A unit operated under the terms of an annual Agreement with ERCOT that is only capable of supplying Volt Amperes Reactive (VAR) that would not otherwise be operated except that it is necessary to provide voltage support under first contingency criteria where Market Solutions do not exist.
    System Benefit Fund The fund established by the PUCT to provide funding for Customer education programs, programs to assist low-income electric Customers; and the property tax replacement mechanism provided by Section 39.601 of PURA.
    System Congestion Fund ERCOT's accounting fund from which payments for resolving Congestion are disbursed and to which ERCOT credits Congestion-related receipts from QSE's representing Loads.
    System Operator An Entity supervising the collective Transmission Facilities of a power region that is charged with coordination of market transactions, system-wide transmission planning, and network reliability.