The Research Of Relay Protection Of Distribution Network With Distributed Power

The development of human beings depends on the energy. Energy is the foundation of human survival and development. It plays an important role in the whole process of human development. However, in recent years, with the development of economy and society, Humans’ demand for energy is larger than before. The traditional energy is faced with depletion. The ecological environment is also destroyed. In order to deal with the potential crisis of energy and deterioration of ecological environment, renewable energy has become a new object of human’ development and research. DG is short for distributed generation. It is a new type of power generation technology which utilize the wind energy, solar energy and biomass energy to power generation and It has been developing rapidly with the advantages of safety, energy saving, environmental protection etc.However, When it is connected to the distribution network, Distributed generation makes single power supply network become multiplex power supply network, changing the distribution of the system flow, so bring great impact for the protection system of the traditional distribution network, leading to the misoperation, refusing action and lower sensitivity of protection, bring a big challenge to the safety and stability of distribution network operation. Therefore, to study the effects which DG brings for the traditional relay protection of distribution network and put forward the coping strategies has very important significance for the application and development of distributed generation technology in the future. Based on the electromagnetic transient simulation software PSCAD/EMTDC, this paper builds a simulation model of relay protection of distribution network with DG, and then carries out a simulation research for a series of effect which DG brings for the traditional relay protection.This paper first introduces the definition of distributed generation, and expounds the five characteristics of distributed generation, analyses the several common types of distributed generation and the equivalent model of distribution network with distributed generation. Then this paper briefly introduces the electromagnetic transient simulation software PSCAD/EMTDC, and uses this software to build the simulation model for the distribution network system. For the effect which the different location and different capacity of distributed power supply brings for the current protection of distribution network, this paper analyses it in theory, then by changing the location and capacity of distributed power supply, analyses the effect which DG brings for current protection. For the effect which DG brings for the distance protection of distribution network, by changing the position of the distributed power, this paper analyses the effect which the distributed power brings for the distance protection I, II section in theory.For the effect which DG brings for the current protection of distribution network, this paper proposes a new method of adaptive current protection of distribution network with distributed generation. According to the operation mode of system and fault type, this method uses compensation coefficient to eliminate the increasing flow effect of downstream main protection which the distributed power brings and the diversion effect of upstream backup protection which the distributed power brings, at the same time establishes the adaptive action criterion of main protection and backup protection of distribution network. Finally, through the PSCAD software simulation, validate the feasibility of the scheme.