A novel PSS-online re-tuning method

The performance of Power System Stabilizer (PSS) strongly depends on its parameters. For fast-changing power systems, some well-tuned PSSs might not provide the expected damping performance after great changes in system structure and operating mode. Therefore, these PSSs need to be tuned again. However, considering the system stability issue, a PSS should not be taken offline once it has been put into service in actual power systems. Under that situation, if a PSS needs to be re-tuned, existing tuning methods cannot be applied since the phase compensation cannot be measured conveniently or even calculated with the PSS in service. This paper proposes a novel PSS-online re-tuning method in order to solve this problem, using local local phasor measurement unit (PMU) measurements. The system closed-loop transfer function (CTF) taking PSS as feedback compensation is identified using the standard Prony analysis. Then, the open-loop transfer function (OTF), which is essentially required for determining PSS parameters, is calculated based on the CTF identification result. The performance of this online re-tuning method is verified by a simulation study of a typical 2-area system. The priority research is also addressed in the same simulation study. Finally, this online-method has been applied to GuiZhou Power Grid (GZPG), which is a provincial grid located in Southwest China. The results from both simulations and field tests in GZPG demonstrate that this online re-tuning method is effective and can be applied to interconnected grids. (C) 2012 Elsevier B.V. All rights reserved.