Performance of Grid-Connected Inverter Fed from PV Array

Abstract

This paper proposes a power flow control strategy based on theory of symmetrical components for implementing bi-directional power flow between the utility grid and local PV array. The system includes a three phase bidirectional inverter with a battery bank at the input interfaced through a boost converter with solar arrays. The battery bank operates in discharge mode when power is fed to the grid and charges from the grid during low demand period. For grid synchronization, principle of phase locked loop (PLL) is implemented in dq synchronous rotating frame (SRF) and PI controller has been used in the feedback loop for the necessary control. The PLL block is implemented using the concept of instantaneous symmetrical component theory. The active and reactive power flow in the grid is controlled by changing the value of reference dc voltage at the input side of inverter. The system has been simulated in PSIM software for a 1kVA inverter. This simple scheme of bi-directional power flow is useful for connecting remote areas with abundant solar energy to the local grid.