Excitation control for high side voltage regulation

Power system events have shown that voltage collapse can be a root cause of some widespread outages. The thrust of this paper is to discuss some means of mitigating system voltage depressions that are available through excitation control of high side voltage. While such control is usually available for individual units through reactive current control, it was difficult to arrange for this control in multi-unit plants where units share a common step-up transformer. Advances in the control architecture allow for such control to be easily implemented. The advantages of this control are outlined in this paper, together with some typical results to show expected benefits. Also, we briefly review some related VAr control strategies for station and system voltage controls and describe their application