A performance evaluation of fuzzy logic controllers for load frequency control in a single area network

Load frequency control is an essential operation performed by power plants to ensure that the system frequency is kept within strict bounds, in the presence of ever-changing loads. In this paper, we are investigating the effect of small step load changes on the frequency of a single area power network. To counteract the resulting frequency deviations, we propose fuzzy logic controllers. Simulations are carried out using Integral, PID (Proportional, Integral and Derivative), as well as fuzzy logic controllers, for small step load changes. The frequency responses are compared, in terms of frequency overshoots, undershoots, rise time, and settling times. A performance index that takes into account the frequency deviation, as well as the control energy of the governor is formulated. Simulations are performed using Matlab Simulink. The PID controller is initially tuned manually, then further tuned using the Matlab Tuner app, from the Control Toolbox. A fuzzy logic controller is designed and implemented. It is observed that that the fuzzy logic controller outperforms the PID, which in turn, is better than the Integral controller. The gains of the PID as well as the fuzzy logic controllers are tuned not only to minimize the frequency deviation, but also to provide an acceptable control energy to the governor, which gives an indication on the opening and the closure of the valves.