Active Voltage-Type Arcing Device Considering Single-Phase Grounding Fault In Distribution Network

In order to ensure the steady development of national economy and social stability,ensure the normal operation of the power system will become the most important.The stable operation of the power system is closely related to the electricity consumption level of the people,but it is essential to ensure the stable operation of the power system and the stable operation of the distribution network of the terminal system.However,as the terminal of power system,the operating conditions of distribution network are very complex and easy to change,which leads to the stability of its operation seriously troubled.Therefore,distribution network is prone to all kinds of unpredictable faults.Among these faults,single-phase grounding fault is the most common,which has a high probability of occurrence,and its harm and influence are extremely bad.This kind of single-phase grounding fault will produce grounding fault current at the fault point.The biggest hazard of the fault current is the occurrence of fault arc.The combustion of fault arc will damage the insulation layer between the phases of the distribution network,so that the single-phase grounding fault will evolve into two-phase or even multi-phase grounding fault.At this time,the distribution network will not be able to continue normal operation,people’s electricity demand cannot be guaranteed,serious harm to social production and development.In order to avoid the occurrence of such problems,how to improve the reliability of power system operation,how to eliminate the single-phase grounding fault in the distribution network,that is,the single-phase grounding fault arc elimination technology,has become an urgent problem to be solved.Before this paper,the research on arc elimination technology of simple distribution network without line impedance has gradually matured,but the line impedance in distribution network cannot be ignored,resulting in a large deviation between research and practice.Traditional active voltage-type arc extinguishing equipment does not consider the impedance of the line in the analysis of arc extinguishing mechanism,resulting in a large error between the calculation of the neutral point voltage offset and the value of the neutral point voltage offset in the real distribution network,and then the applied voltage or current in the subsequent arc extinguishing cannot realize the full compensation of grounding current.In this paper,an active voltage type arc extinguishing device based on voltage inverter is developed.Firstly,the arc extinguishing mechanism of complex distribution network with line impedance is deduced and analyzed,and the mathematical relationship between the value of injection current and line impedance is found.The voltage drop caused by the load current on the line impedance is eliminated by using the difference calculation of the current value before and after the fault phase,and a new algorithm is proposed for real-time calculation of the line impedance of distribution network.Finally,the line impedance value obtained is used for calculation,and then the injection current value used for arc suppression in complex distribution network(considering the real-time line impedance value condition)is obtained,and the reference value of neutral point voltage deviation is corrected.At the same time of obtaining the reference value of the neutral point voltage deviation in complex distribution network,a double closed-loop control strategy is designed by using the quasi-proportional resonance controller to achieve the accurate clamping of the neutral point voltage,and the characteristics of the control strategy are analyzed.Finally,the simulation is carried out on MATLAB/Simulink software platform to simulate the active voltage type arcing equipment for single-phase grounding fault of distribution network under the condition of line impedance.The simulation and experimental data also verified the feasibility and effectiveness of the principle introduced in this paper,indicating that the active voltage type arc suppression method does not need to measure the ground parameters,convenient control,and good economy.And it has good arc elimination performance when low resistance and high resistance ground fault.