Delayed-input power system stabilizer using supplementary remote signals

The design of a local H_∞-based power system stabilizer controller, using wide area or global signals as additional measuring information considering time delay, is presented in this paper. The wide area signals are taken from suitable remote network locations where the oscillations are well observable. A long time delay introduced by remote signal transmission and processing in wide area measurement system (WAMS) may harm system stability and degrade system robustness. Three methods for dealing with the effects of time delay are presented in this paper. To provide robust behavior, H_∞ control theory together with an algebraic Riccati equation (ARE) approach has been applied to design the controllers. The effectiveness of the resulting robust H_∞-based PSS controllers is demonstrated through digital simulation studies conducted on a test power system. The simulation results show that the proposed controller contributes significantly to the damping of inter-area oscillations and the enhancement of small-signal stability in the presence of uncertainty in time delay under a wide range of system operating conditions.