On-line Tuning Of A Fuzzy Power System Stabiliser

A fuzzy logic power system stabiliser (FPSS) has been developed using speed deviation and accelerating power as the controller input variables. The inference mechanism of the fuzzy logic controller is represented by a (7 ~'7) decision table, i.e. 49 IF-THEN rules. The design of the FPSS is based on the linguistic rules which are available from experts, hence, there is no need for a mathematical model of the plant for the design procedure. Two scaling parameters have been introduced to tune the FPSS. These scaling parameters are the outputs of another fuzzy logic system which gets the operating conditions of the power system as inputs. This mechanism of tuning the FPSS, makes the FPSS adaptive to changes in the 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 tuned stabiliser has been tested by performing nonlinear simulations using a synchronous machine-infinite bus model. The responses are compared with the fixed-parameters FPSS and a CPSS. It is shown that the tuned FPSS is superior to both fixed-parameters FPSS and CPSS.