Robust power system stabiliser design under multi-operating conditions using differential evolution

A power system stabiliser (PSS) design method, which aims at enhancing the damping of multipleelectromechanical modes in a multi-machine system over a large and pre-specified set of operatingconditions, is introduced. With the assumption of normal distribution, the statistical nature of theeigenvalues corresponding to different operating conditions is described by their expectations and variances.A probabilistic eigenvalue-based optimisation problem used for determining PSS parameters is thenformulated. Differential evolution (DE) is applied for solving this highly nonlinear optimisation problem.Different strategies for control parameter settings of DE have been studied to verify the robustness of DE inPSS optimisation problems. The performance of the proposed PSS, with a conventional lead/lag structure,has been demonstrated based on two test systems by probabilistic eigenvalue analysis and nonlinearsimulation.