Research On Capacitance-to-ground Current Measurement Technology Of Distribution Network Based On Flexible Full-compensation Arc-suppression Device

With the intelligent development of the power grid,how to use intelligent equipment to automatically reduce the occurrence of grid faults and make the power system safe and stable operation has become the main research direction of power workers.For the most common single-phase ground faults in power systems,the elimination method is closely related to the neutral grounding method.For the neutral point arc-suppression coil grounding system,when a ground fault occurs,the arc-suppression coil can compensate the capacitance current,thereby reducing the residual flow to a certain extent.On the other hand,this grounding method can also reduce the fault phase voltage recovery speed.Because it has significant arc extinguishing effect and can reduce the risk of various types of hazards caused by faults and protect the safety of power grids and equipment,it is widely used in China.The grounding mode of the neutral point through the arc suppression coil is also called resonant grounding according to its working characteristics.When the power grid is in normal operation,the circuit formed by the arc suppression coil and the capacitance to ground can be equivalent to a series circuit,which is in accordance with Kirchhoff’s voltage law.So it is also called the principle of voltage resonance.In the case of a ground fault,the grid can be equivalent to a parallel loop,in accordance with Kirchhoff’s current law,also known as the current resonance principle.In the event of a ground fault,the arc suppression coil can achieve fast and effective compensation,and the grounding arc can quickly self-extinguish.Accurate measurement of the capacitance current in the current operating mode is an indispensable part,and the accuracy of the measurement results will directly affect the tuning and compensation effects of the arc suppression coil.At this stage,various experts and scholars have proposed a variety of methods to measure the capacitance current to the ground,but in practical applications can not achieve the desired results,and even many are still at the level of theoretical analysis.Therefore,based on the efforts of the predecessors,combined with the development of modern technology,this paper proposes a capacitance current measurement method based on flexible full compensation arc-suppression device,and verified by simulation model.In this paper,the neutral grounding method and the arc suppression coil compensation principle are carefully studied.The various capacitance current measurement methods are summarized and analyzed,and the limitations and application scope of each measurement method are pointed out.Secondly,the basic structure and principle of the flexible full compensation arc-suppression device are studied in depth,and the inverter compensation partis studied in detail,and the viewpoint of applying it to the three-phase unbalanced zero-sequence current compensation is proposed.Finally,the capacitance current is measured by the sweep frequency method,and the unbalanced system zero-sequence current compensation method is used to improve the system imbalance,expand the applicable range of the sweep frequency method,and further improve the measurement accuracy of the capacitance current.The feasibility of the proposed method is verified by simulation,and the results show that the measurement results are good.