Performance assessment of PI, PID and Fuzzy-PI-Controllers in migrating voltage sag using Dynamic Voltage Restorer (DVR)

Abstract

The performance of Dynamic Voltage Restorer (DVR) depends on the efficiency of the control techniques used in switching the Pulse Width Modulation (PWM) inverter to inject compensating voltage to the sensitive load during voltage sag. In this paper, performance assessment of three controllers: proportional–integral (PI), proportional–integral–derivative (PID) and Fuzzy- proportional–integral (Fuzzy-PI) commonly utilized in DVR for mitigating voltage sag in a power system is studied. The performances of the controllers are evaluated based on the response time and the harmonic distortion content. They are investigated under balanced 3-phase fault for different load sizes (1000-10000W), through simulation using Sim- Power system in MATLAB™ environment. The results reveal that Fuzzy-PI controller is preferable in terms of response time at injecting compensating voltage to the system during voltage sag with response time of 3µs while PID controller is the most desirable when harmonic content is the subject of concern with the least values of 0.39-0.72 percent for the different load sizes. This paper is useful to the utility operators, researchers and industrial engineers at the planning stage in determining the most appropriate DVR to be deployed based on controller type depending on which of the metrics is in focus.