Design and control of micro-grid fed by renewable energy generating sources

Abstract

This paper presents a micro-grid at an isolated location fed from solar and wind energy sources. DFIG (Double Fed Induction Generator) equipped with MPPT (Maximum Power Point Tracking Technology) is used to harness wind energy. A crystalline solar photovoltaic (PV) system is used to convert solar power which is evacuated at the common DC bus of DFIG. The solar power is fed through DC-DC boost converter which is also equipped with MPPT algorithm to extract maximum solar energy. A battery bank is connected at the common DC bus of the DFIG which acts as buffer storage for exchange of energy. The system is designed for complete automatic operation taking consideration of all the practical conditions. The system is also provided with a provision of external power support for battery charging. The voltage and frequency are controlled through a modified indirect vector control of the load side converter which is incorporated with droop characteristics. It alters the frequency setpoint based on the energy level of the battery. The system is modeled in Sim-Power System tool box of MATLAB and its performance is simulated under varying conditions e.g. unavailibity of wind or solar energy, unbalanced and nonlinear loads has been presented.