The Research Of Hybrid Circuit Fault Location And Automatic Reclosing Technology

With the development of Panjin City Scale, the increase of power load and theexpansion of the city, a large number of66kV substations are bulit near the central ofthe city. At the same time, the construction of infrastructure, part of the powertransmission line is set into the ground.Within the city, transmission lines aremeasured in the case that the power cable line goes underground passage. Oncetransmission lines leave the city, in order to save investment, the overhead line willbe generally taken. It appeared that a lot of transmission lines with cables andoverhead lines operate simultaneously. When the malfunction of Overhead lineshappenedthe most of them are temporary fault.However, the cable line fault is mostlydue to manufacturing defects, operating for a long time or insulation down cause suchas short circuit fault. These faults are all permanent faults. In order to improve thecontinuity of power supply, we generally take the automatic reclosing technology.But for the permanent fault, the automatic reclosing technology may influence thesystem and the stable operation of the system at the same time. This requests that wemust pinpoint the overhead lines-cable hybrid circuit fault.When the fault occurs inthe overhead line, we should protect the device and start the circuit breaker reclosingtransmission, but when fault occurs in the cable, the circuit breaker reclosing is notadopted.The most faults of the overhead lines are temporary fault, but the most faults ofcable line are permanent fault. There are3lines66kv overhead cable hybrid lines,length8.634kilometersfor all, and21lines10kv overhead cable hybrid line, length112.2km for all. In the future, the number of mileage about aerial cable hybrid linewill increase greatly. With the implementation of this project, we can effectivelyimprove system stability and continuity of power supply by reclosing operation whenthe fault occurs in the hybrid of overhead lines section. At the same time it can beavoided that the reclosing on permanent fault once again and the impact on thesystem. It is necessary for us to protect the location request, mainly in mixedconductor between the accuracy of fault location.Based on power grid hybrid circuit in Panjin of LiaoNing province, the basicresearch about data and statistic about the hybrid status are made. Secondly, all kindsof fault data in recent years are organizesd and compared. Thirdly, the methods oftransmission line fault locationare conmpared and the suitable one for mixed linefault location is selected. Finally, the reclosing intelligent control according to thespecific fault location method is realizedand the practical application is carried on,the hybrid fault accurate control is obtained.