modelReferenceBus
Reference bus for an isolated grid
Extends from PowerGrids.Electrical.BaseClasses.OnePortAC (Base class for AC components with one port), Icons.Bus.
Information
When an isolated synchronous grid is initialized in steady state, the reference angle remains undefined. In order to make the angles well defined, this ReferenceBus component should be used in the position where the power flow problem has the slack node.
The purpose of this component when the grid is initialized in steady state is twofold:
- Set the initial voltage of the node to the same value as in the power flow model, i.e. with magnitude
UStartand phaseUPhaseStart - Absorb the excess active power
PSlackand reactive powerQSlackthat allow to balance the power flows at the nominal value of frequency. These two values correspond to the active and reactive power flows into the slack node of the power flow model.PSlackandQSlackthen remain constant throughout the simulation. If the power flow is correcty balanced, those two values are nearly zero, so the Reference Bus is not absorbing any significant active or reactive power during the simulation.
setPhaseOnly is set to true, then only the initial phase of the bus voltage is set to the same value of the power flow, i.e., UPhaseStart. The initial voltage magnitude is computed to ensure zero reactive power flow QSlack.Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Types.Voltage | UNom (from OnePortAC) | Nominal/rated line-to-line voltage | |
| Types.ApparentPower | SNom (from OnePortAC) | Nominal/rated apparent power | |
| Boolean | portVariablesPhases (from OnePortAC) | false | Compute voltage and current phases for monitoring purposes only |
| Boolean | portVariablesPu (from OnePortAC) | true | Add per-unit variables to model |
| Boolean | generatorConvention (from OnePortAC) | false | Add currents with generator convention (i > 0 when exiting the device) to model |
| LocalInitializationOption | localInit (from OnePortAC) | LocalInitializationOption.none | Initialize the component locally in steady state from port start values |
| Boolean | setPhaseOnly | false | = true if only the initial voltage phase is to be set |
| InitializationOption | initOpt | systemPowerGrids.initOpt | Initialization option |
| Types.ComplexPerUnit | nStart | CM.fromPolar(1, UPhaseStart) | Unit phasor with angle UPhaseStart |
| Types.ActivePower | PSlack | Constant slack active power leaving system through bus | |
| Types.ReactivePower | QSlack | Constant slack reactive power leaving system through bus | |
| Initialization | |||
| Types.Voltage | UStart (from OnePortAC) | UNom | Start value of phase-to-phase voltage phasor, absolute value |
| Types.Angle | UPhaseStart (from OnePortAC) | 0 | Start value of phase-to-phase voltage phasor, phase angle |
| Types.ActivePower | PStart (from OnePortAC) | SNom | Start value of active power flowing into the port |
| Types.ReactivePower | QStart (from OnePortAC) | 0 | Start value of reactive power flowing into the port |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| PowerGrids.Interfaces.TerminalAC | terminal (from OnePortAC) |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| PortAC | port (from OnePortAC) | AC port of node | |
| Electrical.System | systemPowerGrids (from OnePortAC) | Reference to system object |