Application Of A Combined System Of APF & SVC To Enhance Power Quality In An Island Microgrid

As the energy and environmental problems become increasingly prominent, the distributed power generation technology is undergoing a significant development in the world. 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. A microgrid can be defined as a low-voltage network with its loads and several small modular generation systems typically interconnected with the utility grid by power electronic devices. The microgrid can be connected with the utility grid, which is the grid-connected mode; it also can operate isolated from the main grid in case of disturbances or faults, which is the island mode.Due to the increasing application of power-electronic loads and the unstable output of renewable energy sources such as photovoltaic and wind farms, harmonics and the variation of the supply voltage amplitude in microgrid are becoming serious problems. How to improve the power quality of the microgrid is an critical issue. Based on analyzing the power quality problems of the microgrid in the island mode, this paper proposes a combined system constructed by APF and SVC to enhance the power quality of the island microgrid. In the combined system, APF, which uses the positive sequence method for harmonic detection and uses Hysteresis control method for current tracking control, is installed at the export of the DG to mitigate harmonic currents produced by inventors; SVC is set near the load to compensate reactive power so as to relieve the voltage variation. The combination of APF&SVC has effectively solved the problems of harmonic and voltage variation of the microgrid in the island mode, thereby improving the power quality of the microgrid.At last MATLAB/SIMULINK is used to establish the simulation models of the island microgrid and simulation results show the effectiveness and fasibility of the combined system.