Research on Admittance Specification Stability of Microgrid at Autonomous mode

In Microgrid (MG) design process, it is usually focus on the stability of microsource (MS). Impedance specification method is an effective approach to analyzing system stability, by defining the ratio of the source/load subsystems impedances and keeping it in the impedance specification. Base on the topology and control strategy of voltage source inverter, the output impedance of inverter is proposed. The influences to output impedance and minor loop gain are discussed which are caused by variations of filter parameters. The stability of the inverter system is researched according to the impedance specification method, and proved by traditional time-domain analysis. Because MG is constituted by numbers of MS operating in parallel at autonomous mode, an admittance specification is proposed, and the stable quantized relation between inverter output and load input admittance is indicated, and the stability of MG system can be ensured by designing the output admittance of MS. The correction and feasibility of proposed admittance specification method are fully verified by simulation results.