Mitigation of detrimental subsynchronous oscillations by linear optimal control with prescribed degree of stability

In this paper, an innovative method is proposed to improve the performance of linear optimal control for mitigation of sub-synchronous resonance in power systems. This method is based on shifting eigenvalues of the state matrix of system to the left hand-side of s plane. It is found that this proposed controller is an extended state of linear optimal controller with prescribed degree of stability. A proposed design, which is presented in this paper, has been developed in order to control of severe sub-synchronous oscillations in a nearby turbine-generator. The proposed strategy is tested on second benchmark model and compared with the optimal full-state feedback method by means of simulation. It is shown that this method creates more suitable damping for these oscillations. The proposed method is applied to the IEEE Second Benchmark system for sub-synchronous resonance studies and the results are verified based on comparison with those obtained from digital computer simulation by MATLAB.