Fuzzy logic based power system stabilizer for damping low frequency oscillations in power system

A Fuzzy Logic Controller for Power System Stabilizer (FPSS) is developed to enhance the performance of a Single Machine Infinite Bus (SMIB) system under steady state and dynamic conditions of the electrical power system. For improving the performance of the system, two inputs FPSS is considered which will damping the oscillations in the system under small disturbances and the two input variables are generator speed deviation (Δω) and acceleration (Δώ) of the machine to which FPSS is connected. One of the main highlights of FPSS are the controller does not require a real time mathematical model of the system for its control action. Fuzzification is performed on the input crisp values to transferring it to fuzzy linguistic variables. For each input variable, there are seven membership functions represented for both input variables and totally they form forty nine fuzzy rules for controlling the stabilizer. The rules were defined based on the system requirement. As the system dynamic characteristics are not known, trial and error methods and the experience play an important role for defining rules. Defuzzification is performed to obtain the crisp controlled variables from the fuzzy set. The paper discuss about the design procedure for FPSS and performance of FPSS is compared with the output response of Proportional Integral Derivative (PID) controlled system.