Power Quality Improvement in PV System Tied to Weak Grid

Abstract

An integrator based positive sequence estimator control is presented for the enhancement of power quality of a grid interfaced double stage solar PV system (GIDSSPVS). This control extracts PSCs (Positive Sequence Components) from the grid distorted and unbalance voltages for the computation of the unit templates and grid reference currents even during grid anomalous situation of grid voltage distortion, voltage sag/swell, DC offset etc. In order to achieve rapid transient response of the system, a feedforward term for the PV array is also applied. The DC-link voltage is also adjusted adaptively for the reduction of the voltage source converter losses during the conditions of the weak grid. The system with an integrator based positive sequence estimator control is simulated in the environment of MATLAB and experiments are conducted on a prototype in the laboratory. Simulation and experimental results validate the satisfactory system performance at different odd states such as intermittent solar irradiations, DC offset, voltage distortions, voltage unbalance, voltage sag and voltage swell. During the grid disturbance and other intermittent conditions, grid currents total harmonics distortion is found as per the IEEE standard-519.