Research On The Problem Relating To The Effect Of Including DG On The Relay Protection Of Transformer Substation

With Promoting the application of renewable energy, Distributed generation becoming one of the most important form of electrical power. But the structure of distribution system will become complex with including a great of distributed generations,distributed generation in the power system will change the present network's structure, its short current strength, current direction and distribution. As a result , that will have various effects on the structure,protection and control of the distribution networks. When the system fault, how much short circuit current from the different Distributed generation to the fault line and how about the time of DG unit steady running that is the basal problem of studying the effect of DG on relay protection of transformer substation. If we study the relay protection of transformer substation including DG unit without care about that question, then we con not get the anticipative purpose. So in this paper, take the biomass energy power plant is included in the 110kV terminal transformer substation of distribution network which is fed by a single source,According to the theory of electric power system and the simulation of EMTDC/PSCAD, analyzes the effect of the different capacity,different access manner and steady running time of distributed generation on the relay protection of distribution network. The conclusion is that the effect of distributed generation on the protection setting value of the transformer substation outgoing line depends on the capability of distributed generation, and the effect of distributed generation on the zone 3 overcurrent protection and distance protection depends on the steady running time of distributed generation.