Research On Fault Recovrry Of Distribution Network Considering Islanding And Reconfiguration

Nowadays,electric power is very important to the stable development of society.The operation mode of power system is flexible,and the failure of power system is inevitable.When the distribution network fails,the dispatcher generally adopts the fault recovery method according to the experience and on-site situation.Network reconfiguration is a method of fault recovery.It can change the network structure by changing the switch.In order to reduce the consumption rate of fossil energy,the utilization of Distributed Generation（DG）has been paid more and more attention.When the fault occurs in the trunk road or the network without contact switch,the distribution network cannot use network reconfiguration to restore power supply.In this case,the distribution network can use DG to form an island.This paper mainly studies island partition and fault recovery reconstruction.According to the location of the fault,formulate the corresponding fault recovery strategy.（1）In view of the situation that the fault point occurs outside the loop and the distribution network is separated from the superior network,the depth first dynamic programming algorithm is used to divide the recovery method of isolated islands.The island partition model aims to recover as many high-priority loads as possible and simplifies the island partition problem to a tree knapsack problem under electrical and topological constraints.On this basis,the controllability and priority of load are further considered,and the island amendment law is formulated to modify them.Finally,safety verification and power regulation are carried out on the islands to ensure the safe and stable operation of each island.An example of IEEE69 node shows that the strategy is effective.（2）For the fault location in the loop,the fault is recovered by reconstruction,and the hybrid Pathfinder algorithm is used.Use topology dynamic update to move the non-fault area to the safety line.A reconfiguration model aiming at network loss and voltage stability is established.Taking IEEE-33 node as an example,the fault recovery was carried out in two cases where the DG was not connected and the DG was connected to the distribution network respectively.The results show the effectiveness of the fault recovery and reconstruction strategy.（3）In the case of interlocking failure of distribution network,a two-layer fault recovery strategy considering island and reconfiguration is formulated.The islanding and reconfiguration model is placed in the bi-level programming model,and the goal is to restore the total power of important loads and the active power loss of the network.The upper model is used to achieve the partition of islands.The lower layer is a network reconfiguration model based on the island partition results.Through the interaction between the upper and lower layers,breadth first search algorithm and hybrid Pathfinder algorithm are used to solve them respectively.Taking IEEE-33 node as an example,this two-layer fault recovery strategy is superior to other fault recovery strategies.