PID-fuzzy logic hybrid controller for grid-connected photovoltaic inverters

This paper presents a novel PID-Fuzzy logic hybrid controller to improve the dynamic response of the output active power and reactive power of a grid connected PV inverter. The combination of PID and flexible fuzzy logic controller makes the control of nonlinear objects, such as the electricity grid, more feasible. The proposed integrated PID- Fuzzy logic controller module automatically varies the coefficients Kp, Ki, Kd whenever there are any changes of the desired power and load. The comparison of simulation results, obtained separately from a PID-controller and a PID-Fuzzy controller embedded in a PV inverter, shows the advantages of the proposed algorithm in terms of time response, overshooting and stability error. It also shows that the proposed controller maintains its response better than the PID controller in many aspects, regardless of changes of grid parameters during operation.