Research On The Method Of Distribution Network Protection Configuration With Distributed Generation

With the development of the technology of distributed generation,the penetration of distributed generation has led to the change of the traditional radial distributionnetwork-based,from which the power supply network will change into double-ended or multi-ended.The old current protection fails to satisfy the demands,to move fast and accurately.Therefore,it is very important of studying the method of distribution network protection configuration with distributed generation.The detailed tasks are as follows:Firstly,the common types of distributed generation and grid-connected patterns are analyzed,the typical distribution network model is built,the simulation analysis to short-circuit current of the location under protection is undertaken in order to study the influence of distributed generation connected to distribution network upon current protection from different situations.When the reclosing in distribution network with distributed generation is under fault,the simulation research of the influence of reclosing operation upon distribution network is carried on,which is concluded that the reclosing in distribution network with distributed generation is operated under the condition of both sides synchronization and the improvement methods are proposed.Secondly,as to the situation of mono-distributed generation connected to distribution network,on the principle of minimum costs and uncomplicated means of communication,the methods of improvements on the original distribution network protection devices is studied.Through the monitor of operational parameter of the system on real time under the protection of microcomputer and then the occurrence of the fault and the types of fault are judged by the algorithms.Adaptive current quick-break protection algorithm is used to realize the automatic movement of relay protection.It includes two aspects concretely:(1)based on the fault locations,the real-time setting method and the introduction of compensation coefficient method is applied separately.The setting value of adaptive adjustment is calculated to realize the protection setting of rotary mechanical and electrical type distributed generation.(2)as to the situation of inverter type of distributed power source injection,the positive sequence fault component method is used to realize adaptive current velocity protection setting calculation.The method is validated through simulation data that it is reliable to move within the protection domain and effectively meet the protection requirements.Finally,as to the situation of numerous distributed generation connected to distribution network,hierarchical regional decision of wide area protections is introduced into the distribution network.According to the comparison of network structures before and after distributed generation connection,the partition of static and dynamic state of the network is undertaken,then,the specific fault locating is done by means of variation of the amplitude of fault current and D-value of phase angle.The first fault locating ensures the fault associated region;the second fault locating judges the specific fault point.The fault cutting-off is realized by the operation of the local LMU.This thesis analyzes the practical examples of distributed generation to testify the validity of the methods and the adaptive dynamic partitioning of the region.The criterion of the method is simulated to meet the purpose of fault locating.In that case,the related breaker is disconnected to cut off the fault.