Research On Fault Recovery Method Of Multi-Source Distribution Network Considering Active Islanding Mode

The high proportion of distributed generation in modern power system makes the system operation more diversified,and the fault types and mechanisms tend to be complex,which brings great challenges to the reliability of power supply.Therefore,taking the rapid recovery of load power supply in non-faulty power loss area after fault isolation as the main research goal,a multi-source distribution network fault recovery method considering active island mode is proposed.The BFGS trust region algorithm is used to analyze the power flow of island power grid with unbalanced nodes,and the effects of four different load types on island operation are compared:constant power load,commercial load,residential load and industrial load.An active islanding recovery method of multi-source distribution network considering the uncertainty of distributed generation is proposed.The randomness of distributed generation output and load fluctuation are characterized by calculating the system interval power flow.The islanding is divided by taking the interval minimum value as the data fixed value of system power flow calculation,and the islanding recovery scheme is determined by the directional traversal of network topology.The power flow calculation method of islanding power grid with unbalanced nodes is used to verify the islanding recovery scheme,which proves the effectiveness of the active islanding recovery method.A fast fault recovery method of multi-source distribution network combining active islanding and network reconfiguration is proposed.The distribution network is partitioned based on network layering.According to the basic loop matrix of the minimum self-healing unit,active islanding/network reconfiguration is used to recover the load power supply in the non-faulty power loss area.If it is recovered through network reconfiguration,heuristic rules are used to close the tie switch that meets the conditions to recover the load power supply in the non-faulty power loss area,calculate the current carrying capacity of branches at each layer of the network,exchange the status of all section switches and tie switches that meet the conditions,and cut off the load if there are still overload lines.Comparing the effects of four different load types on island operation,it is concluded that the island system with large fluctuation cannot meet the operation requirements of constant power load.At the same time,it is proved that the power flow calculation method of island power grid with unbalanced nodes is effective.Taking PG&E 69 nodes system as the example,the effectiveness of the islanding recovery scheme is verified by using the unbalanced node islanding power flow calculation method.Comparing with the other three islanding recovery methods,the results show that the islanding recovery method takes less time than the existing methods and can recover more important load power supply.Through the recovery blind area of acti ve island recovery network reconstruction,the fault recovery of multi-source distribution network is maximized.Taking TPC 84 nodes system as the example,compared with other four distribution network fault recovery methods,the results show that this fault recovery method has less switching action times and less time-consuming than the existing methods,which proves the superiority of this fault recovery method.