Bipolar type DC microgrid

Abstract

Traditional AC grids have been well established in the Power field of industry from generation, transmission to distribution. This is a direct effect of the war of the currents in the 19th century which saw the AC current being victorious over DC due to a significant flaw of which it was economically unviable to convert voltage and it would also too complex to construct. There is an increasing sense of urgency for the Earth to start finding alternative way to generate electrical energy. The traditional method of generating electricity has been under pressure to be removed due to the emissions of greenhouse gases as a result of burning oil, coal and natural gas to generate electricity. Furthermore, [1] has predicted that mankind will exhaust the reserves which are technologically possible to access for these natural resources required to generate electricity by 2081. As such it becomes more urgent to find alternative ways to generate electricity. Fortunately, in the recent years’ technology has developed with renewable energy technology emerging. Photovoltaic(PV) panels have better efficiencies and become viable to generate and cope with small demands. DC starts to rise in popularity again as these renewable energy resources either could supply DC power only or would be more efficient in general to generate DC power. However, with the AC grid so established it would be more beneficial to integrate DC micro grids into the AC in order to integrate these renewable energy resources. As such, this project will study and simulate a simplified version of a DC micro grid simulating the renewable energy as the source as a DC constant. The micro grid includes a boost DC-DC converter to convert the voltage to a higher voltage level which is more optimal for transmission. The project also studies the bipolar circuit topology for its usefulness and reliability in the micro grid and simulates the half bridge DC-DC converter to balance the voltage of both branches. Finally, this project studies and simulates the PI tuning to control the voltage output for the Boost DC-DC converter and the Half Bridge DCDC converter. PLECS and PSIM were used to simulate the power and control circuit and MATLAB was used to find the bode plots for the respective open loop systems.