Voltage balancing of converter fed microgrids with single phase loads

This paper analyzes a sequence network diagram of a converter fed islanded microgrid with single phase and three phase loads. The analysis shows that the converter needs to inject negative sequence current into the microgrid to keep its voltage balanced. This result is used to synthesize a control scheme that allows a single VSC with standard inductor interface and dq frame current control to operate in intentional islanding mode in the presence of unbalanced loads. This control scheme injects real and reactive power into the microgrid to regulate its voltage and frequency respectively, while injecting negative sequence current current to eliminate the negative sequence component of the microgrid voltage due to single phase loads.