PID control for improving P&O-MPPT performance of a grid-connected solar PV system with Ziegler-Nichols tuning method

This paper uses the Ziegler-Nichols (Z-N) tuning method approach combined with adjustments of the Proportional-Integral-Derivative (PID) gain parameters to achieve satisfactory improvement in the open-loop Perturb-and-Observe (P&O) maximum power point tracking (MPPT) performance of a grid-connected solar photovoltaic (PV) system. Various modes of the PID control produced varied effects and improvements in performance compared to the open-loop response. The P-controller reduced the open-loop overshoot by 62.28 % and the settling time by 166 ms, but introduced ripples. The PI-controller also reduced the open-loop overshoot by 70.99 % and reduced settling time by 106 ms, but increased the rise time slightly over that of the P-controller. The PID-controller virtually eliminated the overshoot, reducing it from 35.06 % to 0.51 %, and also increased the system response time by 236 ms. The superiority of the PID controller is thus confirmed as it virtually eliminated the overshoots, connoting a significant reduction in losses. The settling times were also reduced, signifying a much faster system response.