Robust Control of Uncertain PV System for Improved Performance by Smith Predictor and H _∞ Loop Shaping Controller

ABSTRACT

The significance of photovoltaic (PV) plants among renewable energy systems is unparalleled due to their ozone‐friendly features. However, their inherent nonlinear behavior for various uncertainties (due to change in irradiation) renders the suboptimal performance. Thus, there is a need for robust controllers. On the basis of daily operation curve of PV plant, parametric uncertainty is incorporated in nonlinear PV time delay models. Further, an intelligent H _∞ loop shaping controller is designed to improve the performance of PV plant subjected to parametric variations. The uncertain PV plant output with H _∞ loop shaping controller is compared with conventional PID controller and Smith Predictor control techniques. Simulation results show degraded performance with PID controller whereas Smith Predictor performs better. However, the best dynamics are obtained with H _∞ loop shaping controller for all operating points. The robust control design yields in significant reduction in rise time, settling time, rapid disturbance dismissal with a short peak time. Further, sensitivity and complementary sensitivity analysis is also carried out to validate the stability and robustness of plant with proposed H _∞ loop shaping controller under all operating points. Thus, proposed H _∞ loop shaping controller enhances the performance, stability and robustness of system manifolds for all operating points under uncertainty and nonlinearity.