Switched shunts

The switched-shunt model selects susceptance from a block schedule according to its control mode.

Block schedule

A switched shunt is a bank of up to eight blocks, each with a step count NI and a step size BI in Mvar at 1.0 per unit voltage. Together the blocks define the available susceptance range and discrete operating points.

Fixed operation (MODSW = 0)

The susceptance is held at BINIT and contributes to the network as a fixed shunt.

Discrete voltage control (MODSW = 1)

The shunt switches among the admissible schedule values to hold the controlled bus voltage within [VSWLO, VSWHI] in per unit. The controlled bus is named by SWREM (SWREG in revision 34 files). At the solution the voltage lies within the band or the shunt rests at the end of its range.

Continuous voltage control (MODSW = 2)

The susceptance varies continuously between the extremes of the schedule. At the solution the controlled voltage lies within [VSWLO, VSWHI], or the susceptance rests at an end of its range.

Plant reactive control (MODSW = 3)

The shunt adjusts so that the reactive output of the local plant is held within the band [VSWLO, VSWHI], interpreted in Mvar.