Robust load frequency control by solid-state phase shifter based on ℋ∞ control design

This paper proposes a new robust control strategy for load frequency control (LFC) by using a solid-state phase shifter. The controller might be implemented also as a new ancillary service for LFC in a deregulated power system. A phase shifter located in series with a tie line between two areas is capable of modulating the tie-line power quickly, which should be applicable to the aggressive control of the system frequencies. A controller for alleviating the frequency fluctuations against a sudden load disturbance by enhancing the damping of inter-area oscillation mode, is designed on the ℋ^∞ control theory with a reduced power system model. Therefore, it has the advantages in the low order configuration of controller, in the high robustness as well as in the good disturbance attenuation performance. In addition, the controller uses only a local frequency deviation as its control signal input. The effectiveness of proposed “ℋ^∞, phase shifter” for the LFC is confirmed in a two area interconnected power system with several system uncertainties and a sudden load disturbance