CIM Issues #5099
Not possible to properly model variable shunt reactor
It is not possible to properly model variable shunt reactor which has “Large regulation ranges from 20% to 100%”. ShuntCompensator has implicit range 0% to 100% as only maximum sections are listed, while 0 section (or 0 Mvar) is presumed to be available. For VSR this is not true. Only way for a VSR to have 0 Mvar is to disconnect it using an external switch.
Since variable shunt compensator cannot be linear because g=Re(1/(r+jx)) it is enough to specialize the NonlinearShuntCompensator class.
Proposed note for the specialized class VariableShuntCompensator:
A variable shunt compensator is a oil-filled reactor with discrete on-line regulation of reactive power. The regulation range typically varies between 30% and 100% of rated reactive power. When energized VSR cannot have a reactive output of 0 Mvar, so minimal valid section number is 1 with reactive power output at either 100% or at minimal reactive power output (reactive power can raise or fall with increasing section number).