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Frequency and amplitude modulation with back to back converters in a utility connected microgrid

Inverters paralleled in microgrid have various forms. Back to back converters due to its isolation characteristics of frequency and fault have been widely researched. This paper designs a control strategy for the back to back converters, which includes the inverter connected to utility (VSC1) and the inverter connected to microgrid (VSC2) respectively. So VSCI can only exchange active power with public grid and VSC2 realizes the frequency and amplitude of microgrid secondary modulation. Bidirectional power flow between the grid and microgrid is realized by maintaining the DC bus voltage constant. The control strategy can not only increase the grid connection characteristics of micro grid, but also improve the voltage quality of the micro grid and realize the power balance and redistribution of active and reactive power. Finally the control strategy is verified in MATLAB.