Impact Of Distributed Generation To Relay Protection Of Distribution Network

Distributed generation is less pollution or pollution-free clean energy. The main typesof distributed generation have wind turbines, solar photovoltaic cells, fuel cells,micro-turbines. Distributed generation usually locates close to the user and supplies power.With the system in parallel, it usually access10kV distribution network.The traditional three-current protection configured in the system side of thedistribution line, each protection element operating current setting value and protectionaction time limit to achieve coordination and cooperation between the correspondingprotection. Thanks to distributed generation, the structure of system changes. The structureof system between the system power and distributed generation changes into adouble-ended power supply line. Compared with the distributed generation is notconnected to the distribution network, the short-circuit current of the protection device willincrease or decrease, or short-circuit current of the opposite direction. This may affect thecorrect action of protection device.Three-current protection device of distributed networkwith distributed generation may result in mistake or refuse to move.This article describes several distributed power structure, principle and mathematicalmodel, the electrical energy types which distributed generation directly produces havefrequency alternating current, direct current and frequency is not identically equal to50HZAC. For the latter two, distributed generation can be connected to distributed networkthrough the rectifier inverter grid. This article describes operation mode of distributedgeneration. And when distributed network appears to fault, the distributed generation howto work. On this basis, though analysis of distributed network operation, it is usuallyconstant power control. Therefore, constant power control of distributed generationsimulation model in MATLAB and typical distributed power access10kv distributionnetwork simulation model are built.According to simulation when a short circuit occurs in different locations of the line,as well as different capacities distributed generation access distribution network, I get theSituation changes of short-circuit current in line protection, and then analyzes thethree-current protection affected.At the same time, when distribution lines with distributed power appears to fault ofdifferent locations, I do the formula derivate and theoretical analysis of the short-circuit current. Through theoretical analysis and MATLAB simulation concluded. Therefore, inthe fifth chapter proposed measures for improvement of the distribution network protectiondevice.