Flexible AC Transmision System FACTS

A: A. That underestimates demand because SCR=2 means voltage sensitivity is dominated by source impedance not nominal kV. B. That misses current saturation at depressed voltage and would brown out during faults. C. That overcorrects by assuming a stiff grid and drives unnecessary converter silicon. D. Using the weak-grid approximation gives order-of-magnitude consistency with STATCOM current limits and the ±0.05 pu target.

A: A. That fails LVRT because thyristor susceptance collapses with voltage. B. That misses the 20 ms response window by orders of magnitude. C. That still derates reactive output at deep voltage sags. D. The VSC topology maintains current injection even at 0.2 pu, meeting grid code timing.

A: A. That confuses series and shunt behavior and predicts the wrong sign. B. That ignores the initial improvement in steady-state power-angle margin. C. That’s a shunt-compensation instinct applied to a series device. D. Reducing X raises Pmax per the power-angle relationship until SSR limits intervene.

A: A. That’s a dielectric stress issue not driven by torsional modes. B. That’s a component heating concern unrelated to mechanical resonance. C. That’s a transient stability problem, not SSR. D. Unmitigated SSR excites torsional modes leading to mechanical damage over time.