Analytical structure of PID fuzzy logic power system stabilizer

Power system stabilizer must be capable of providing appropriate stabilization signals over a broad range of operating conditions and disturbances. Traditional power system stabilizers rely on linear design methods. To cover a wider range of operating conditions, fuzzy logic power system stabilizers are proposed. Design of fuzzy logic power system stabilizer (FLPSS) is not an easy task. It is very important to appropriately tune the parameters used in FLPSS. These parameters are commonly determined by trail and error method, which is rather time consuming. Hence deriving an analytical structure for the fuzzy controller is very important as it gives the mathematical structure to the FLPSS rather than the 'black-box' approach. In the present paper a systematic approach through analytical structure of PID FLPSS. We have proved that a FLPSS is a nonlinear PID controller. And it is equivalent to a linear PID controller around the equilibrium point. Based on the analytical expressions, the FLPSS is designed to obtain the optimum response. The dynamic response of FLPSS following perturbation in excitation for a single machine connected to infinite bus bar is observed. The robustness of the controller is emphasized.