Application of a combined system to enhance power quality in an island microgrid

Efficient and effective use of renewable energy, distributed generation and energy storage can solve global problems such as energy crisis and climate change. A promising solution to interconnecting these distributed energy resources with the utility grid is the microgrid paradigm. Due to the dispersion of distributed sources and loads, different distributed sources use the different control strategies. Microgrid is usually interconnected with the utility grid by the inverter, which causes to many current harmonics in the export of the inverter. Without the support of the utility grid, the variation of reactive power of the loads in the island microgrid will lead to voltage fluctuation. Under the premise of assuming that the microsource could supply adequate active power to the loads, this paper proposes a combined system constructed by Shunt Active Power Filter (SAPF) and Static Var Compensator (SVC) to improve the power quality of the island microgrid, in which SAPF uses the positive sequence method for harmonic detection and uses Hysteresis control method for current tracking control and is adopted near the microsource to mitigate harmonic currents and SVC is set near the load to compensate reactive power so as to relieve the voltage variation. Simulation results show the effectiveness of the combined system.