Control of Multifunctional PV-Battery Storage System with Power Quality Enhancement of Utility Grid

Abstract

This paper presents the control for the multifunctional photovoltaic (PV) battery storage system with power quality (PQ) enhancement of utility grid. The current control of voltage source converter (VSC) utilizes adjustable momentum factor with normalized error based filter in the grid intertied mode at normal operation and in the voltage control of VSC, when the utility grid disrupts as a result of some contingency at the distribution network. In this system, the assemblage of the battery is by using a DC-DC bidirectional converter, which is discharged and charged as per the load perturbations. It also maintains the voltage for maximum power point (MPP) tracking at the DC link. The control has smooth and fast convergence, as active weight current constituent of nonlinear load is obtained by adjustable momentum term with weight updates of preceding two values and variable step size with normalized error. The current control is utilized for power factor correction, harmonics eradication and enhancement of system’s dynamics with PV feed-forward part. The system’s behaviour is found satisfactory and validated through test results in steady state and dynamic scenarios i.e. solar insolation and load alteration, load unbalance, grid voltages anomalous condition, like swell / sag. The smooth transition operation via a solid state switch between two modes, ensures uninterrupted and suitable power to the load at the utility grid outage. The perturb and observe (P & O) technique is utilized to obtain MPP from PV array. The voltage control technique regulates load frequency and voltage during grid fault.