A Method for Automatic Tuning of PSS under Restriction of Robustness

Abstract

A method for PSS parameter tuning under restriction of robustness is proposed. In the design procedure, the proposed method uses a low-order linearized model which reprepsents dominant dynamics of the power system. The ignored higher order modes and pertuabation of the low frequency modes are considered as multiplicative perturbations. The controller with high performance and high robustness can be derived by solving a nonlinear optimization problem.
Because of the non-convexity of the optimization problem, gradient methods are not suitable for solving the problem. For this reason, the present paper proposes utilization of genetic algorithm (GA) for solving the nonlinear programming problem.
The present paper makes it clear through digital simulations using a simple three-machine power system model that the designed controller is effective for damping interarea modes and achieves higher robustness against change of load flow condition than the well tuned conventional controller.