A Voltage Stability Control based on Impedance Estimation for the Independent Microgrid

The impedance distribution and characteristics of microgrid system tend to be complicated because of the diversification of DGs types and uncertainty in accessing to microgrid, which not only affects the operational performance of the microsource with conventional control method, but also the stability of the microgrid system. To deal with the uncertainty of line impedance, a feeder power-flow control strategy of microsource inverters based on line impedance real-time estimating is proposed in this paper. The feeder impedance of the microsource is estimated with the extended Kalman filter algorithm, so the distribution factor of feeder reactive power can be adjusted accordingly. The simulation and experimental results show that the distributions of the feeder reactive power flow of the microsource could be optimized using the proposed control strategy, and the voltage stability of the microgrid system could be improved.