Application Of Multi-satellite Navigation System In Single-phase-to-earth Fault Location

Single-phase ground fault is the most common fault in small current grounding system.It is difficult to measure the fault signal because of weak current when the system has a single-phase ground fault.Long time operation with a grounding point is prone to cause phase-to-phase short circuit,resulting in larger accidents.Therefore,the location of single-phase ground fault in small current grounding system is a difficult problem to be solved at home and abroad in the development of distribution network automation.This paper analyses the domestic and foreign location methods of single-phase ground fault.Combining the current state of domestic distribution automation,the zero sequence current phase comparison method is used as the judgment basis of the fault location.When single-phase ground fault occurs on the line,the system and line generate zero-sequence voltage and zero-sequence current,because the three phase voltage and current of line-to-ground capacitance are no longer balanced.According to the formula derived and vector diagram analysis,we can get the phase difference between zero-sequence current and zero sequence voltage in non-fault line and fault line.In non-fault line,zero-sequence current flows from the bus side to user side,and the phase of zero-sequence current fronts zero-sequence voltage 90 degrees.But in fault line,zero-sequence current flows from the user side to bus side,and the phase of zero-sequence current behinds the zero-sequence voltage 90 degrees.This paper designs a single-phase ground fault location detection device based on ARM Cortex-M4 core architecture.The device contains one host and two slaves.Each device integrates power collection,satellite positioning and timing service,and wireless communication,enabling synchronization of high-precision clocks in multiple satellite systems.The power is collected on the line of the user side and the bus side,and the FFT(Fast Fourier Transform)is used to calculate the parameter of the required power.The slave transmits data to the host through Bluetooth communication,and the host processes the data.When the central station queries,the host transmits the processed data to the central station through Zigbee wireless communication.The central station processes the data to obtain the amplitude and phase of the power parameter,and ultimately it can locate the fault line and position accurately.