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Glossary and Acronyms

A | C | D | E | F | H | I | O | P | R | S | U | V | W | Z

A

  • AC: Alternating current

  • ACE: Area control error

  • AGC: Automatic generation control

  • AVR: Automatic Voltage Regulator

C

  • CA: EIA prime mover code for the steam turbine (combined cycle steam) portion of a combined cycle plant

  • CAISO: California Independent System Operator

  • CC: EIA prime mover code for combined cycle units

  • CT: Combustion Turbine

D

  • DC: Direct current

  • DERA1: Distributed Energy Resource Aggregate model Type A1, the PSS®E implementation of the WECC DER_A dynamic model

  • Deterministic: mathematical model in which the outcomes are precisely determined through known relationships among states and events. For contrast, see the definition of Probabilistic.

  • Dynamic: Refers to data and simulations for power system transient simulations using differential equations. Common examples include signal stability analysis to verify the power system will maintain stability in the few seconds following an unexpected fault or generator trip. For contrast, see the definition for Static data.

E

  • EIA: U.S. Energy Information Administration

  • EIM: Energy Imbalance Market

  • EMF: Electromotive force

  • ESAC: IEEE Type AC Excitation System model

  • ESDC: IEEE Type DC Excitation System model

  • EXAC: IEEE Type AC Excitation System (modified) model

  • EXPIC: Proportional/Integral Excitation System from PSS/E

  • EXST: IEEE Type ST (Static) Excitation System model

  • EX4VSA: IEEE Excitation System for Voltage Security Assessment with Over-Excitation Limits.

F

  • Forecast: Predicted values of a time-varying quantity that commonly features a look-ahead and can have multiple data values representing each time period. This data is used in simulation with receding horizons or data generated from forecasting algorithms. See the article on Time Series Data.

  • Forecast window: Represents the forecasted value starting at a particular initial time. See the article on Time Series Data.

H

  • Horizon: Is the duration of all time steps in one forecast. As of PowerSystems.jl version 4.0, all horizons in PowerSystems.jl are represented as a Dates.Period. For instance, many Day-ahead markets will have an hourly-resolution forecast for the next day, which would have a horizon of Dates.Hour(24) or Dates.Day(1). If the forecast included the next day plus a 24-hour lookahead window, the horizon would be Dates.Hour(48) or Dates.Day(2). See the article on Time Series Data.

  • HRSG: Heat Recovery Steam Generator

  • HVDC: High-voltage DC

I

  • IEEET: IEEE Type I Excitation System.

  • Injector or Injection: Injectors refer to models that represent how a generator or storage device injects power or current into the power system. Loads are negative injectors. In PowerSystems.jl, some components can accept data for both StaticInjection and DynamicInjection models for both static and dynamic modeling.

  • Interval: The period of time between forecast initial times. In PowerSystems.jl all intervals are represented using Dates.Period types. For instance, in a Day-Ahead market simulation, the interval is usually Hour(24).

  • Initial time: The first time-stamp in a forecast window. See the article on Time Series Data.

  • IPC: Interconnecting power converter

L

  • LCC: Line Commutated Converter HVDC line

O

  • OEL: Over Excitation Limiter

P

  • PCC: Point of Common Coupling. The point where a generator or plant connects to the grid.

  • PLL: Phase-locked loop

  • PSS: Power System Stabilizer

  • PSSE or PSS/E: Siemens' PSS®E Power System Simulator for Engineering

  • PPA: Power purchase agreement

  • PSI: PowerSimulations.jl

  • PSID: PowerSimulationsDynamics.jl

  • PSLF: GE Vernova's Positive Sequence Load Flow Software

  • PSY: PowerSystems.jl (this package)

  • pu or p.u.: Per-unit

  • PWM: Pulse-width modulation. A switching technique used in power converters to synthesize a desired AC output voltage by rapidly toggling switches at a high frequency.

R

  • REECB1: Renewable Energy Electric Controller Type B1
  • REPCA1: Renewable Energy Power Controller Type A1
  • Resolution: The period of time between each discrete value in a time series. All resolutions are represented using Dates.Period types. For instance, a Day-ahead market data set usually has a resolution of Hour(1), a Real-Time market data set usually has a resolution of Minute(5).

S

  • SCRX: Bus Fed or Solid Fed Static Exciter

  • SEXS: Simplified Excitation System model from PSS/E

  • SIL: Surge impedance loading

  • ST: Steam Turbine

  • States: Correspond to the set of inputs, outputs or variables, that evolve dynamically in PowerSimulationsDynamics.jl, commonly via a differential-algebraic system of equations. In PowerSystems.jl, a component associated to a DynamicInjector (for example an AVR) specifies the set of states that specific component requires to be modeled accurately.

  • Static: Typically refers to steady state data or models where the power system and each of its components are assumed to be operating at a steady state equilibrium point. This includes both power flow data for a single time point simulation as well as quasi-static time series data and models, where the power system is at an equilibrium point at each time step. Static data can be used as the input to single time point power flow models and production cost models with, for example, 5-minute, 15-minute, or 1-hour Resolution. For contrast, see the definition for Dynamic data.

  • STAB: Speed Sensitive Stabilizing PSS Model

  • Struct: A composite data type in Julia that can store multiple values in a single object. See the Julia documentation on struct and Composite Types.

  • SVM: Space vector modulation. A control algorithm for three-phase inverters that represents the desired output voltage as a vector in the complex plane and selects switching states to approximate it, achieving lower harmonic distortion than basic PWM.

U

  • UUID: Universally Unique Identifier. A 128-bit identifier formatted as a 32-character hexadecimal string (e.g. 5f180c4c-cd81-4b80-8c60-627c28aef8b0).

V

  • VSCLine: Voltage-Source Converter HVDC Line

  • VSM: Virtual Synchronous Machine

W

  • WECC: Western Electricity Coordinating Council

  • Window: A forecast window is one forecast run that starts at one initial time and extends through the forecast horizon. Typically, a forecast data set contains multiple forecast windows, with sequential initial times. For example, a year-long data set of day-ahead forecasts contains 365 forecast windows

Z

  • ZIP load: A ZIP load model accounts for the voltage-dependency of a load and is primarily used for dynamics modeling. It includes three kinds of load: constant impedance (Z), constant current (I), and constant power (P), though many dynamics models just use the constant impedance model. StandardLoad is a ZIP load model that breaks up the load into each of its three components. ExponentialLoad instead expresses the voltage dependency as an exponential equation, of which the ZIP components are special cases.