Module qlimits 

Reactive-limit enforcement: the PV → PQ switch.

A PV bus holds its voltage by producing whatever reactive power that takes. A real machine cannot: past q_max (or below q_min) it saturates, the voltage falls away from target, and the bus is no longer a PV bus at all — it is a PQ bus injecting exactly its limit.

This is the standard MATPOWER-style one-directional switch: a bus that moves PV → PQ stays there for the rest of the run. The reverse switch (a PQ-clamped bus whose voltage overshoots its target, which should return to PV) is deliberately not implemented — it is where the literature’s oscillation reports come from, and the one-directional form is what every reference gridoxide is checked against uses by default.

Structs

QLimitReport

Which buses this loop moved off voltage control, and whether it settled.

ReactiveLimits

Enforces q_min/q_max on every PV bus by switching violators to PQ.