| With the development of the power system, both the load and the diverse demands of users are increasing, the present power system increasingly shows its disadvantages. In the case of the global energy shortage and the growing environment pollution, the microgrid, as one of the efficient, environmental protective, more reliable power supplies, can improves the power quality, safety of the power supply, power system stability, as well as energy saving and environmental protection. On the basis of the research background of the microgrid at home and abroad, the protection technology of the microgrid is studied in this dissertation.First of all, the concept and the characteristics of the microgrid are introduced as well as the microgrid structure proposed by the Consortium for Electric Reliability Technology Solutions(CERTS). And then, the types and characteristics of the distributed generation (DG) and the research background of the protection of the microgrid are described in detail.Secondly, the influences of the capacity and place of the DG on the short current, protection coordination and re-closure are analyzed.As the microgrid includes many DGs and is very vulnerable, the relay coordination computation is relatively complicated and the time interval of protection coordination is long. The non-communication protection can be utilized to estimate the fault zone according to the superimposed phase current of the sound phase after the tripping of the breaker of the other end of the faulty line. In this case, the tripping speed of the breaker of the local end of the faulty line is advanced. Therefore, the non-communication protection is introduced into the protection configuration of the microgid based on the traditional over-current protection in this dissertation. The CERTS based microgrid is modeled based on the PSCAD/EMTDC software and the effectiveness of the proposed protection method is validated by means of simulation tests.
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