Research On Distribution Network Capacitive Current Measurement And Single-Phase-to-Ground Fault Line Selection

With the continuous development of modern industry,there are many different grounding methods for power systems grounding practices,and foreign countries have different choices under other conditions.Among them,the neutral point is grounded through the arc suppression coil and does often used in the distribution network due to the reliability of its power supply.And with the emergence of adjustable and pre-adjusted arc suppression coils,it is possible to perform total compensation for arc suppression coils.However,this compensation method also has problems that need to be solved.For example,accurately measuring the capacitance to the ground to tune the arc suppression coil and accurately using the transient signal to select the fault line after the fault occurs is of great significance.Based on the above problems,this paper first analyzes the traditional signal injection method to measure the capacitance current to the ground.The conventional signal injection method for measuring the capacitance of the distribution network to the ground has the advantages of simple operation,high safety,and small error.But it is difficult to determine the frequency of the injected signal,and the calculated capacitance to ground differs for different combinations of frequencies.At the same time,the voltage transformer excitation and leakage impedance have a significant impact on the measurement.As a result,conventional signal injection methods present difficulty in selecting frequency combinations,the complexity of calculations,and limitations in the range of system-to-ground capacitance measurements.For the above problems,this paper improves the traditional signal injection method.By injecting high-frequency signals into the open secondary side of the TV,the resonant frequency of the ground capacitor of the distribution network and the leakage inductance of the TV obtain by using the sweep method.The ground’s capacitance value can calculate from the equivalent circuit and related equations.In distribution networks with large ground capacitance,the technique improves by using series capacitors to solve the problem of low accuracy of the high-frequency method in systems with large ground capacitance.Finally,the effectiveness of the technique verifies experimentally.For distribution network,resonant grounding system single-phase ground fault routing problem.In this paper,to improve the accuracy of fault routing based on the traditional method.We propose a multi-strategy collaborative multi-objective mothballing optimization algorithm optimized for line selection by a variational modal decomposition algorithm.Firstly,the zero-sequence current signal of the faulty line decomposes by the optimized variational modal decomposition algorithm.The energy weights of the modal components obtained from each decomposition do then calculated separately,and the magnitude of the energy weights discriminates the fault lines.The results of the simulation experiments prove that this method can effectively filter out the noise of the signal and effectively filter out the noise of the signal.It can also accurately extract the practical information of the fault signal to determine the fault line accurately—improved accuracy based on traditional methods.There are 34 figures,14 tables and 56 references in this paper.