Microgrids have many new characteristics

such as bi-directional current

different fault current amplitudes when operating in grid-connected and islanded modes

flexible structures and so on

which challenge microgrid protection. Despite the evident advantages over other protective methods based on the fault component principle

as most distributed generators are connected to the grid through an inverter

their fault features are mainly influenced by the control strategy and obviously differ from traditional synchronous generators. Thus the existing analytic method of fault components is no longer applicable

which makes it imperative to study the adaptability of fault component protection to microgrids with inverter interfaced distributed generators(IIDGs). In this paper

aimed at the equivalent model of IIDG under PQ control

an additional fault network of microgrid including IIDGs is built. Then by comparing the fault component of positive sequence current in the fault feeder with those in other feeders of the same bus

the fault component principle is analyzed from the perspective of amplitude and phase. Finally

the effectiveness of the proposed analytic method is evaluated through microgrid simulation in the PSCAD software environment. This work is supported by National Nature Science Foundation of China(No. 51407128)and Shanghai Science and Technology Committee(No. 12ZR1451300).