Calculation and measurement of harmonic impedance for a microgrid operating in Islanding mode

Stability analysis is very important in the design and in the operation of microgrid, because microgrid always contains many Distributed Generations(DGs), power electronic converters and constant power loads. Harmonic impedance is a useful parameters in the stability analysis. In this paper, the structure of microgrid is introduced detailed. The control strategies of inverter operating in different mode are discussed. The calculation of each component of microgrid is studied, and then a harmonic impedance theoretical calculated value of microgrid is given. An example microgrid model is developed in PSCAD. The harmonic impedance of microgrid is measured by injecting a current disturbance. Simulation results show that the theoretical calculated value is coincident with the measured value. The calculation of harmonic impedance for microgrid is valid.