Enhancing the damping ability of wide-area power system by employing time delay

Time delay in wide-area damping control has been a big barrier in engineering application of power system stabilizer (PSS) based on wide-area measurement system (WAMS). Unlike conventional viewpoint that time delay is detrimental to system stability and should be disposed of or compensated additionally, in this paper, time delay is considered essentially neutral and introduced into the proposed wide-area PSS structure. By employing the extra time delay in the wide-area PSS to make the total time delay of a control loop match the optimal value, the lead-lag compensation block can be removed from the classical PSS, and the damping effect will be enhanced remarkably under a definite feedback gain. Simulation results on the 10-machine 39-bus New England test power system confirm the concept that a delicately designed time delay can be beneficial to system stability. The wide-area PSS employing delay matching block performs satisfyingly in low-frequency oscillation suppression under constant and random time delays for a wide range.