I assisted with an SVC commissioning last week. The SVC was installed primarily for flicker mitigation, but also for power factor control. The commissioning Engineers were focused on these goals, not EAF performance.
SVCs always improve EAF performance and efficiency. On startup, the SVC reduced flicker and controlled power factor well, but I knew something was wrong when there was no improvement in EAF performance. After modeling and analysis of the power system using the ArcView software I was able to show the commissioning Engineers the issue. There was not enough capacitive VARs in steady state to stabilize the medium voltage. Voltage sag coupled with pure impedance regulation was resulting in reduced arc power.
After making some adjustments to the SVC control, the improvement in EAF performance was incredible.