EXPLORATORY CONCEPTS ON CONTROL OF VARIABLE SERIES COMPENSATION IN TRANSMISSION-SYSTEMS TO IMPROVE DAMPING OF INTERMACHINE/SYSTEM OSCILLATIONS

Of much current interest is the application of power electronics in ac transmission systems notably to control power flow in series elements through variable series compensation. Principles of control of such variable series compensation to damp intermachine and intersystem oscillations are developed based on the concept of reactance with dynamic characteristics similar to reactances of synchronous machines. It is shown that the measured through-power in series branches is a logical source of local control intelligence for modulation of series compensation in such branches. Nonlinear control logic schemes developed from linear analysis are demonstrated in simple examples of single and multimachine ideal sources in pure reactance networks.