Performance of a self-tuned fuzzy-logic power system stabilizer in a multimachine system

The performance of a fuzzy-logic power system stabiliser (FPSS), which is tuned automatically as the operating conditions of the power system change, is investigated by applying it to a multimachine power system. Firstly, a FPSS is developed using speed deviation and accelerating power as the controller input variables. Secondly, two scaling parameters are introduced to tune the FPSS. These scaling parameters are the outputs of another fuzzy-logic system, which gets its inputs from the operating conditions of the power system. This mechanism of tuning the FPSS makes it adaptive to changes in operating conditions. Therefore, the degradation of the system response, under a wide range of operating conditions, is less compared to the system response with a fixed-parameter FPSS and a conventional (linear) power system stabiliser (CPSS). The responses of the system with the three power system stabilisers (PSSs), namely CPSS, FPSS and self-tuned FPSS, are compared. It is shown that the tuned FPSS is superior to both CPSS and fixed-parameter FPSS.