Comparative Assessment of PID, Fuzzy Logic and ANFIS Controllers in an Automatic Voltage Regulator of A Power System

A comparative study and performance analysis of three different controllers - namely proportional-integral-derivative (PID), PD-like fuzzy logic and adaptive neuro fuzzy inference system (ANFIS) - utilized to control the output voltage of an automatic voltage regulator (AVR) of a power system are carried out. The obtained results show that the PID controller is capable of rejecting simultaneous disturbance signals effectively with zero steady-state error (SSE). However, it is not robust to unexpected parameter changes of the system. On the other hand, the fuzzy logic controller shows the ability to resist changes in the system parameters. Nonetheless, it exhibits both an increase of 12.5% in the SSE and fluctuations in disturbance rejection test. On the contrary, the ANFIS controller shows: i) superior performance and ii) robustness to disturbance signals and changes in the system parameters compared to the other two controllers. For these reasons, we believe that utilization of an ANFIS controller will not only promote safety, but also reliability of the AVR in power systems.