Research On Single Phase Grounding Fault Location System For Transmission Line

With the development of power network interconnection, the scale of power system is extending, the scale of the Non-Effectively Grounded Power Systems is increasing. Because the voltage class of the Non-Effectively Grounded Power Systems is lower, single phase grounding fault is easily occurred. If single phase grounding fault is occurred, fault current is very small, so it can continue to run for 1~2 hours according to the protocol. While in the case of single phase grounding fault, the voltage to ground of non-fault phase rises, if occurring intermittence arc ground, it can cause arcing overvoltage, and insulation of the system is spoiled. It easily causes phase-to-phase short circuit, happens power cut accident, consequently caused economic loss. If the fault point can be found quickly and accurately, The consumer will not be influenced much. Therefore, it has prodigious actual significance. And the single phase grounding fault location for transmission line should be the emphases in power system fault detection.This paper systematically analyses existing domestic and foreign methods for single phase grounding fault location. Because the impedance fault location method is easily influenced by the factor such as fault resistance, transformer error and asymmetrical line configuration, the fault location accuracy is lower. Traveling wave fault location method can be classified into active traveling wave method and passive traveling wave method. It adopts passive traveling wave method that measures the fault distance on line. If fault at the voltage crossover point happened, because of the quantitative sudden change of traveling wave which brought by the fault point is very small and its variation is mild, it causes the front of traveling wave is hard to be detected. Therefore, it cannot measure the distance based on traveling wave. It adopts active traveling wave method that measures the fault distance on line. If measuring the distance by the signal coming from both sides, there is a problem that datum time at the both sides must be synchronization. So it needs to equip communication channels with good stability. This paper presents a fault location method that is based on traveling wave method with one side, sending the direct current signal to transmission line that is off line. In this way, it can acquire the time margin from sending out the signal to returning the traveling wave, accordingly carry it out that single phase grounding fault point locate fleetly. Based on this location method, it presents the hardware and software system in detail.The digital signal process technology is applied in the project. It is a new technique that develops rapidly and be used widely. The TMS320VC5402 data signal processor of TI Company is...