Extrapolate maxQ and minQ reactive limits when outside active power limits in ReactiveCapabilityCurve

[SylvestreSakti]

Describe the current behavior

Currently, when computing reactive limits of a generator (or a battery) that is defined by its ReactiveCapabiltyCurve, when P is out of the bounds of this curve (e.g. when a generator is in starting phase, its P is inferior to Pmin), the computed reactive limits are the same as the reactive limits of Pmin.

Describe the expected behavior

We would like to extrapolate the reactive limits to have a more accurate modelling of the generator when it is outside its active power limits.

Describe the motivation

Differences in modeled behavior are detected when generators are in starting phase, and having extrapolation of the reactive limits enables a more accurate modelling.

Extra Information

This modification may need a modification of getMinQ() and getMaxQ() of the class ReactiveCapabilityCurve in powsybl.iidm.