Applications of Fuzzy Supervisory PID Controller to a Power System

This paper presents a way that fuzzy logic can be used in high level control functions. Specifically, we examine the use of fuzzy logic in supervisory control, for selecting discrete control actions, identifying the operating environment and evaluating controller performance. Proportional integral derivative (PID) controllers are widely used in excitation control of power systems, they exhibit poor performance when the controlled systems contain unknown linearities. The main objective of this paper is to simulate the use of fuzzy logic to provide new control functions that are outside the domain of the PID control-where fuzzy control is likely to provide the greatest payoff. Simply, a supervisory correction term is added to the input of the PID controller. The supervisory correction term is the output of fuzzy supervisory controller. A performance demonstration of the proposed scheme via the excitation control of a single-machine infinite-bus system subjected to a wide variety of transient disturbances is presented in this paper. Our results show that the fuzzy supervisory PID controllers have high performance compared to PID controllers with significant reduction in overshoot and undershoot. The scheme can be easily implemented in practice by adding a fuzzy supervisory controller to the existing PID controller