On-line Monitoring Method Of Ground Fault For Power Transmission Line Based On The Sectional Transfer Function

With the expanding power grid, the structures of the grid become complex, and the transmission voltage level is also rising, and the transmission line will increase the probability of failure. If the fault can not be excluded, a huge losses for the national economy will be caused, and it will also cause great inconvenience for people. The transmission line faults directly affect the reliability of the running system. Fault exclusion is conducive to reduce the loss caused by the blackout, with great social and economic benefits. According to statistics, in the transmission lines'fault of distribution network, the ground fault occurred in almost the majority of times.Thus, regarding the transmission line safe reliability service, seeking one kind of transmission line online monitor method of transmission line ground fault appears important.For line monitoring of transmission line ground fault, a new sectional transfer function based method is proposed for power transmission line on-line fault detection. And the transmission line ground fault online monitor could be realized.The transfer function is loaded into the transmission line ground fault monitoring in the article. And two new definitions are given. In the method, the deviation of the power transmission line sectional transfer function values from the values in the normal working condition is extracted and used as the features reflecting the operating status of power transmission lines. By the detection principle of the transmission lines based on the method of segment transfer function, the corresponding algorithm of the transmission line ground fault monitoring is established. And the equivalent circuit parameters of simulation for 10kV, LGJ-70 ACSR overhead transmission line model are given. Based on the SIMULINK, the simulation model of power line carrier of overhead transmission lines is built, which provides an effective simulation platform for the method involved in the article. Then, some of the basic principles of selectling the frequency of power carrier are proposed. By these principles, the final selected frequency of the power carrier is 95.5 kHz. And then, the simulation analysis for the low resistance ground fault and the high impedance fault of overhead transmission lines is implemented. The Simulation results show that the proposed algorithm of transmission line fault detection could effectively and correctly identify the locations of fault. Also, the proposed method is proved to be effective. Finally, the impact of the proposed algorithm by the change of the load impedance of the transmission line is studied. And some inadequacies of the proposed method are found out, which provide some references for further study in future.