Ratio tap changer

The com.powsybl.iidm.network.RatioTapChanger interface is used to model a ratio tap changer device on a transformer. It can be added to both two windings transformers and three windings transformers.

# Characteristics

Attribute Type Unit Required Default value Description
LowTapPosition int - no 0 The position index of the tap changerâ€™s low tap
TapPosition int - yes - The position index of current tap
LoadTapChangingCapabilities boolean - no false true if the ratio tap changer has load tap changing capabilities, false otherwise
Regulating boolean - no false true if the ratio tap changer is regulating, false otherwise. State variable
TargetDeadband double - no Double.NaN The deadband used to avoid excessive update of controls
TargetV double kV yes - The target voltage
RegulationTerminal Terminal - no - The terminal which voltage is regulated

Each step of a ratio tap changer has the following attributes:

Attribute Type Unit Required Default value Description
$r_{r, tap}$ double % yes - The resistance deviation in percent of nominal value
$x_{r, tap}$ double % yes - The reactance deviation in percent of nominal value
$g_{r, tap}$ double % yes - The conductance deviation in percent of nominal value
$b_{r, tap}$ double % yes - The susceptance deviation in percent of nominal value
$\rho_{r, tap}$ double p.u. yes - The voltage ratio in per unit of the rated voltages

# Model

A ratio tap changer is regulating if both Load tap changing capabilities and Regulating are set to true. Remote control can be modeled by setting a distant terminal as the regulation terminal.

For more information on how ratio tap changers are taken into account in the transformers model, please refer to the two windings transformers documentation and the three windings transformers one.

# Examples

This example shows how to add a ratio tap changer to a two windings transformer:

twoWindingsTransformer.newRatioTapChanger()
.setLowTapPosition(-1)
.setTapPosition(0)
.setRegulating(true)
.setTargetV(25)
.setRegulationTerminal(twoWindingsTransformer.getTerminal1())
.beginStep()
.setRho(0.95)
.setR(1.)
.setX(2.)
.setG(0.5)
.setB(0.5)
.endStep()
.beginStep()
.setRho(1)
.setR(1.)
.setX(2.)
.setG(0.5)
.setB(0.5)
.endStep()
.beginStep()
.setRho(1.05)
.setR(1.)
.setX(2.)
.setG(0.5)
.setB(0.5)
.endStep()