The Research For Overvoltage Protection And Insulation Coordination Of DC Distribution Network Scheme

Compared with the AC distribution network,the DC distribution network has many unique advantages,such as its transmission capacity is generally large,its power quality is generally high,its commutation loss is generally low.it is generally There is no problem of system synchronization stability and it can also support various distributed power access,etc.Not only is it economical,but also its reliability is relatively high,therefore,more and more attention in the industry society is beginning to favor DC power distribution Construction and development of the network.However,because the DC distribution system is often accompanied by overvoltage and overcurrent when the system fails,the fault needs to be removed effectively and in time.The DC circuit breaker plays a key role in the DC distribution network,but at the same time The protection strategy has become complicated due to the use of DC circuit breakers,which has brought new challenges to the selection of key equipment and insulation coordination methods for DC distribution networks.Therefore,it is of great significance to conduct in-depth research on the problems of overvoltage protection and insulation coordination in DC distribution networks.The topological structure and modeling method of key equipment in ± 10kV three terminal flexible DC distribution system are analyzed in this paper..According to the system parameters and control and protection strategy requirements,the electromagnetic transient simulation model of DC distribution system is built in PSCAD software,and the steady-state operation of the system is verified.Then,the key problems of various typical faults in AC and DC side of the system are analyzed Based on the analysis of over-voltage of the location,the maximum over-voltage level is obtained;then,the traditional over-voltage protection method is used for reference,and the configuration scheme of the arrester protection is given.The simulation comparison is carried out under the two conditions of not configuring the arrester and configuring the arrester,and the results of the maximum over-voltage of the key location of the system and the corresponding decisive fault conditions are obtained.Then,based on the DC distribution system self According to the characteristics of the system,the insulation coefficient suitable for DC distribution network is proposed and optimized,and the insulation level of the important equipment in the AC and DC side of the system is obtained.The article is based on the Zhuhai ±10kV flexible DC distribution network system.For the configuration of the arrester and the insulation level of the corresponding equipment,it not only guides the design and selection of key equipment,but also can be used for other DC distribution networks.The project provides a certain reference for the application of overvoltage protection and insulation coordination.