Research On The Strategy Of Multifault Recovery Considering DG And Load Degeneration In Active Distribution Network

In active distribution network,With the increasing penetration of distributed energy and diversification of energy dispatch and the using of the power electronic devices and various intelligent electrical equipment,the complexity of the control and coordination between various devices are likely to be interfered by the outside world and the probability of failure will increase.Therefore,when the active distribution work occurs multiple faults,how to fully coordinate and using all kinds of recovery sources to recover loss of power and put forward a set of fast and effective multi-fault repair strategy is very significant.Based on the above background and significance,the main work of this paper is as follows:Firstly,the graph theory is introduced,the methods of depth-first researching(DFS)and reachability partition method are summarized;Considering the time-varying of distributed power output and load demand,a distributed power supply and time-varying load model is established,laying the foundation for the later study of the dynamic restoration strategy.Secondly,for rapid recovery of multifault in active distribution network,a two-phase repair model of multiple faults in the active distribution network is established.In the first stage,the first rush repair point of failure is quickly determined,and an initial recovery strategy is formulated with the goal of recovering the lost load more frequently with the priority of recovering the important load.In the second stage,the maximum loss of power recovery will be restored as the upper optimization objective and the least comprehensive economic loss as the lower optimization objective.A two-layer optimization model for repair and restoration will be established.In this paper,considering the time-varying of DG output,a multi-period islanding strategy is proposed to solve the problem of stable power supply of loss-of-load during the repair of the fault.Finally,basing on the reachability partition method in graph theory,this paper establishes a multifault dynamic partition recovery model for the active distribution network.After occurrence of multiple faults,basing on the autonomy and coordination ofthe multi-agent system,the optimal recovery strategy for each sub-region is selected according to the indicators of power loss recovery rate.The bacterial colony chemotaxis(DBCC)algorithm is embedded in the multi-agent system and the optimal repair and recovery strategy is geted by coordination and optimized the goal of minimizing economic loss.At the same time,considering the communication failure,the 95598 system and the professional knowledge of the repair team could be regarded as a source of information for the repair system to make decisions for multiple faults recovery.By 95598 system and their professional knowledge,The repair team updates repairing orders of the fault point that the repair team is responsible for,and completes multifault repair as soon as possible.