Enhanced resonant two‐degree of freedom‐based PID controller for grid‐integrated PV power generating system

Abstract

The contribution of power because of the nonconventional energy sources is enhancing day by day. This gives rise to power converter connected to the grid for an integration and to utilize the nonconventional energy sources economically and efficiently. However, this causes the distortion in the grid voltages and currents. All advanced high precision operating machines and measuring instruments are sensitive to the harmonics of the grid voltages. Therefore, this work illustrates an improved control to supress the grid voltage and current harmonics caused by an integration of non-conventional energy source and nonlinear loads. An enhanced resonant two-degree of freedom proportional-integral-derivative (ER-2-DOF-PID) controller is used to extract fundamental components from load currents. It uses a resonant controller in shunt with PI controller to suppress the multi-order harmonics and steady state error. A DC-offset is used in parallel of this combination to suppress the sub-order harmonics. To suppress the peak overshoot during the load transients and insolation changes, a 2-DOF-PID controller is used. The presented control is investigated by developing its model in MATLAB environment and this is validated on a prototype developed in the laboratory. The controller is modelled and investigated for stability analysis using a Bode mathematical tool..