Research On Distribution Network Fault Recovery With Distributed Generation Under Storm Wind Weather

With the deterioration of the environment,the probability of extreme weather events becomes more frequent.This kind of disaster event with low probability and high impact brings about the security problem of distribution network.Extreme weather events attack distribution networks,which may lead to long-term outage for days to weeks,economic losses and security threats.How to quickly solve the distribution network fault and restore the power supply of users,so that the distribution network can operate safely,stably and economically,has become the focus of many scholars.Distributed renewable energy(DG)access to distribution network brings new opportunities and challenges for distribution network failure recovery in extreme weather disasters,makes distribution system more complex,and provides more flexibility for altermative power supply.Isolated Island partition and fault reconfiguration are the most frequently used methods for fault recovery of distribution network with a large number of DGs.Isolated Island partitioning refers to the use of DG's ability to supply power to the user side and alone,to reasonably divide and control its output,and to restore power for key loads in a fault distribution system.Fault reconfiguration is to transfer the load of the fault line to the normal running Iine through the contact switch between feeders.Neither Island partition nor fault reconfiguration takes into account the secondary attack of extreme weather events on the network after recovery,which leads to network re-destruction.Aiming at the problem of network reliability after fault recovery,this paper firstly analyses the advantages and disadvantages of different DGs in distribution network and their effects on the safety,reliability and loss of distribution network,which lays a foundation for the later DGs to restore the fault of distribution network.Secondly,the impact of extreme weather events(storms)on distribution network is studied,and a severe risk index(SRI)is proposed to evaluate the online risk analysis of the impact of extreme weather events on distribution network space-time.The number of manageable failure scenarios is generated in each simulation step by using LHS and reverse reduction algorithm to calculate SRI.In the numerical simulation,the distribution network is tested with IEEE-24 nodes,and the method is evaluated in two different storm intensity scenarios,considering the maximum prediction errors of 0%and 10%wind speed in the next hour.The results show that this method can accurately estimate the impact of extreme events on the system even when the prediction error is acceptable,and can fully achieve the expected load rejection effect.Finally,a method of using DG to restore critical loads of distribution lines after disaster is proposed,which considers the robustness after restoration.A new measure UR is defined to quantify the restoration unavailability of the restored distribution lines,and a MILP problem is established,robust restoration schemes for possible secondary faults of distribution lines after restoration are obtained under operation and connection constraints.The simulation test of IEEE-123 nodes distribution system shows that the network topology structure using recovery strategy can satisfy both network failure probability and DG availability.In addition,it is proved that this strategy restores the maximum number of critical loads when considering the damage of distribution feeders.