Equivalent Circuit Analysis of Power System Reactive Power and Voltage Control Problems

The paper presents a method of analysis of power system reactive power and voltage control problems by means of known equivalent circuits of power systems and of power transformers with tap-changers. The method yields insight into the physical effects of tap-changer operations on system reactive power flows and voltage changes and enables one to get reasonably good quantitative estimates of the magnitude of these changes. The method also yields insight into "optimum" strategies for tap-changer controllers in order to optimize transformer operation and enables one to determine tap-changer requirements for system control problems such as reactive power transfers between systems.