Analysis And Improvement Of Active Voltage Arc Suppression Algorithm For Distribution Network

Single-phase grounding faults account for the vast majority of all types of faults in the distribution network,and whether they can be handled correctly and effectively is directly related to the safe operation of the power grid.At present,most of my country’s medium-voltage power distribution network uses the neutral point to be grounded through the arc suppression coil to reduce the impact of single-phase grounding faults.With the development of the distribution network and the rapid increase of nonlinear loads and the large-scale use of power electronic equipment,the active and harmonic components in the ground fault current also greatly increase.Even if the traditional passive arc suppression technology can completely compensate the fundamental reactive components,the larger active and harmonic components are enough to maintain the arc,which will generate arc grounding overvoltage,increase the contact voltage and step voltage of the person,and be safe for the person.And the safe and reliable operation of power grids and equipment poses threats.Therefore,the study of active arc suppression technology has very important theoretical and practical significance.The development of power electronics technology makes it possible to completely compensate the active and harmonic components in the ground fault current.This article studies the active voltage arc suppression method.The main contents are as follows:First,the research background,significance and passive and active arc suppression technology at home and abroad are reviewed.Then it introduces several important concepts about low-current grounding in detail,and then mathematically derives the normal-operation low-current grounding system and the low-current grounding system after a single-phase grounding fault.Then the arc suppression mechanism of active voltage arc suppression is analyzed,and the overall design scheme is given.The phenomenon that the residual current does not decrease but increases when the active voltage is extinguished with low resistance grounding is analyzed theoretically,and the influencing factors of the residual current are simulated and verified.In order to achieve the goal of controlling the ground phase voltage to zero,using closed-loop control technology,the control algorithm based on the double closed-loop quasi-proportional resonant controller is introduced,and the open-loop and closed-loop frequency characteristics of the voltage outer loop and the current inner loop are analyzed.An improved voltage arc suppression algorithm is given,which uses the functional relationship between the transition resistance and the neutral point voltage and the ground phase power supply voltage to budget the resistance value.If it is greater than the threshold value,the fault phase voltage is controlled to zero,if it is low At the threshold value,the fault phase voltage is controlled as the voltage drop of the fault line to ensure that the current at the fault point will not increase.Use Matlab/Simulink simulation software to establish related models,and compare the methods before and after optimization.The results show that the optimized voltage arc suppression algorithm is simple to measure,convenient to control,and has good arc suppression in both low-resistance and high-resistance grounding.The effect is easy to realize,which is conducive to the practical application of the active arc suppression method,and has feasibility and effectiveness.