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 |
| SASM | Supplemental Ancillary Services Market |
| SCADA | Supervisory Control And Data Acquisition |
| SCED | Security-Constrained Economic Dispatch |
| SCUC | Security-Constrained Unit Commitment |
| SDRAMP | SCED Down Ramp Rate |
| SE | State Estimator |
| SFT | Simultaneous Feasibility Test |
| SGIA | Standard Generation Interconnection Agreement |
| SMOG | Settlement Metering Operating Guides |
| SPS | Special Protection Systems |
| SRR | Statewide RPS Requirement |
| STEC | South Texas Electric Cooperative |
| STLF | Short-Term Load Forecast |
| STWPF | Short-Term Wind Power Forecast |
| SURAMP | SCED Up Ramp Rate |
| SWCAP | System-Wide Offer Cap |
| Sampling | The process of selecting a subset of a population of Customers that statistically represents the entire population. |
| Scheduled Power Consumption | Expected Load, in MW, reported by a QSE for a Controllable Load Resource pursuant to Section 6.5.5.2, Operational Data Requirements. |
| Scheduled Power Consumption Snapshot | A snapshot, taken by ERCOT, of the Scheduled Power Consumption provided by the QSE for a Controllable Load Resource at the end of the adjustment period and used in determining the Controllable Load Resource Desired Load. |
| 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. |
| Security-Constrained Economic Dispatch (SCED) | The determination of desirable Generation Resource output levels using Energy Offer Curves while considering State Estimator (SE) output for Load at transmission-level Electrical Buses, Generation Resource limits, and transmission limits to provide the least offer-based cost dispatch of the ERCOT System. |
| Self-Arranged Ancillary Service Quantity | The portion of its Ancillary Service Obligation that a QSE secures for itself using Resources represented by that QSE and Ancillary Service Trades. |
| Self-Schedule | Information for Real-Time Settlement purposes that specifies the amount of energy supply at a specified source Settlement Point used to meet an energy obligation at a specified sink Settlement Point for the QSE submitting the information. |
| Service Address | The street address associated with an ESI ID as recorded in the Customer Registration Database. This address shall conform to United States Postal Service Publication 28. |
| Service Delivery Point | The specific point on the system where electricity flows from the TSP or DSP to a Customer. |
| Settlement | The process used to resolve financial obligations between a Market Participant and ERCOT. |
| Settlement Calendar | A calendar that provides information on when Settlement Statements and Invoices shall be posted, payment due dates, and dispute deadlines. Additional information is provided in Section 9.1.2, Settlement Calendar. |
| Settlement Interval | The time period for which markets are settled. |
| Settlement Invoice | A notice for payment or credit due rendered by ERCOT based on data contained in Settlement Statements. |
| Settlement Meter | Generation and end-use consumption meters used for allocation of ERCOT charges and wholesale and retail Settlements. |
| Settlement Point | A Resource Node, Load Zone, or Hub. |
| Settlement Point Price | A price calculated for a Settlement Point for each Settlement Interval using LMP data and the formulas detailed in Section 4.6, DAM Settlement, and Section 6.6, Settlement Calculations for the Real-Time Energy Operations. |
| Settlement Quality Meter Data | Data that has been edited, validated, and is appropriate for the 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 Statements for the Day-Ahead Market, and Section 9.5, Settlement Statements for Real-Time Market. Day-Ahead Market (DAM) Resettlement Statement The Settlement Statement issued for a particular DAM using corrected Settlement data, in accordance with Section 9.2.5, DAM Resettlement Statement. Day-Ahead Market (DAM) Statement The Settlement Statement issued for a particular DAM, as further described in Section 9.2.4, DAM Statement. Real-Time Market (RTM) Final Statement The RTM Settlement Statement issued at the end of the 59th calendar day following the Operating Day, as described in Section 9.5.5, RTM Final Statement. Real-Time Market (RTM) Initial Statement The first iteration of an RTM Settlement Statement issued for a particular Operating Day, as further described in Section 9.5.4, RTM Initial Statement. Real-Time Market (RTM) Resettlement Statement The RTM Settlement Statement using corrected Settlement data, in accordance with Section 9.5.6, RTM Resettlement Statement. Real-Time Market (RTM) True-Up Statement The RTM Settlement Statement issued 180 days following the Operating Day, as further described in Section 9.5.8, RTM True-Up Statement. |
| Shadow Price | A price for a commodity that measures the marginal value of this commodity; that is, the rate at which system costs could be decreased or increased by slightly increasing or decreasing, respectively, the amount of the commodity being made available. |
| Shift Factor | A measure of the flow on a particular Transmission Element due to a unit injection of power from a particular Electrical Bus to a fixed reference Electrical Bus. |
| Short-Term Wind Power Forecast (STWPF) | An ERCOT produced hourly 50% probability of exceedance forecast of the generation in MWh per hour from each Wind-powered Generation Resource (WGR) that could be generated from all available units of that Resource. |
| Simple Transmission Outage | See Outage |
| Special Protection Systems (SPS) | A set of automatic actions to be taken to relieve transmission security violations (normally post-contingency overloads or voltage violations) that are sufficiently dependable to assume they can be executed without loss of reliability to the interconnected network. |
| Split Generation Resource | See Resource |
| Startup Cost | All costs incurred by a Generation Resource in starting up and reaching LSL, minus the average energy produced during the time period between breaker close and LSL multiplied by a heat rate proxy “H” multiplied by the appropriate FIP, FOP, or $1.50 per MMBtu, as applicable and as described in the Verifiable Cost Manual. The Startup Cost is in dollars per start. |
| Startup Loading Failure | An event that results when a Generation Resource is unable to operate at Low Sustained Limit (LSL) at the time scheduled in the Current Operating Plan (COP) which occurs while the unit is ramping up to its scheduled MW output. A Startup Loading Failure ends when the Resource:
|
| Startup Offer | An offer for all costs incurred by a Generation Resource in starting up and reaching LSL, minus the average energy produced during the time period between breaker close and LSL multiplied by a heat rate proxy “H” multiplied by the appropriate FIP or FOP. The Startup Cost is in dollars per start. |
| State Estimator (SE) | A computational algorithm that uses Real-Time inputs from the network’s Supervisory Control and Data Acquisition (SCADA) system that measure the network’s electrical parameters, including its topology, voltage, power flows, etc., to estimate electrical parameters (such as line flows and Electrical Bus voltages and Loads) in the ERCOT Transmission Grid. The SE’s output is a description of the network and all of the values (topology, voltage, power flow, etc.) to describe each Electrical Bus and line included in the system model. |
| State Estimator (SE) Bus | An electrical node of common voltage at a substation that consists of one or more Electrical Buses tied together with closed breakers or switches. |
| Sustained Response Period | The period of time beginning ten minutes after ERCOT’s issuance of a Verbal Dispatch Instruction (VDI) requesting EILS deployment and ending with ERCOT’s issuance of a VDI releasing the EILS Loads from the deployment. |
| Switch Request | A request submitted by a CR on behalf of a Customer to switch service from the Customer's current CR to the requesting CR. |
| Switchable Generation Resource | See Resource |
| Synchronous Condenser Unit | A unit operated under the terms of an annual Agreement with ERCOT that is only capable of supplying Volt-Amperes reactive (VArs) that would not otherwise be operated except that it is necessary to provide voltage support under first contingency criteria. |
| 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 that supervises the collective Transmission Facilities of a power region. This Entity is charged with coordination of market transactions, system-wide transmission planning, and network reliability. |
| System-Wide Offer Cap (SWCAP) | The system-wide offer cap defined in subsection (g) of P.U.C. SUBST. R. 25.505, Resource Adequacy in the Electric Reliability Council of Texas Power Region. |