New techniques for measuring impedance characteristics of an islanded microgrid based on stability analysis

Microgrid stability is related to system control mode and various parameters of the system. These important parameters of microgrid have some connection with impedance parameters. Therefore, the input and output impedance is an important parameter to analyze the microgrid stability. Impedance criterion is further deduced to make it easy to use. This paper also introduces a new method of impedance measurement for microgrid based on square wave current injection. In order to verify the measurement results, microgrid impedance of each part and the impedance of overall microgrid are calculated. A simulation model of the three-phase AC microgrid is developed in PSCAD. The AC system harmonic impedance measuring device is developed. Measurements verify the proposed new technique. © 2015, The editorial office of Transaction of China Electrotechnical Society. All right reserved.