Photovoltaic micro-grid for GD with active and reactive power injection control for connected and islanded operation

Abstract

This paper presents the implementation of a micro-grid with photovoltaic generation and local accumulation based on lead-acid batteries, considering its capability to operate connected or islanded from the utility grid. The system will supply power to utility grid through six single-phase inverters, three of them operating only in grid-tie mode and the other three operating in grid-tie mode or islanded mode to guarantee the continuous power supply to local loads. Supporting the stability and power quality for the utility grid, lead-acid batteries afford the backup energy allowing the electric power supply for the utility in absence of photovoltaic generation. Nowadays, most of the inverters for distributed generation (DG) are designed to provide active power with a fixed power factor or follow a predetermined pattern in function of the grid voltage and frequency. In this paper the inverters are used to dynamically control the active and reactive power supply, allowing the system to act as an active compensator at the point of common coupling, improving the power quality. This DG system is complemented with management software for power flow monitoring and databases for long term analysis.