| In the context of rapid economic development in the society,the reliability of power supply in distribution network is becoming more and more important.However,the distribution network system will often be malfunctions on line,in which are mostly single-phase grounding fault.Because the power supply of the system can not be guaranteed to be safe under the conditions of single-phase grounding fault,it is very important to cope with the adverse effects on the distribution network.In order to solve the problems on medium and low voltage distribution network,relevant experts first put forward the method of compensating arc extinction by grounding the neutral point through the passive arc suppression coil.In the past,when the scale of distribution network is small,the passive arc suppression coil can basically meet the requirements of arc suppression compensation for single-phase ground fault system.However,as the distribution network becomes more and more complex,the content of active current components and harmonic current components in single-phase ground fault currents becomes larger and larger.The practice shows that the traditional passive arc suppression coil can not compensate the active and harmonic current components,and the more complex the distribution network arc suppression effect is less ideal.In order to make the arc suppression compensation more effective and improve the reliability of the distribution network,it is necessary to study a comprehensive arc suppression method of single-phase ground fault in medium and low voltage distribution network,to realize the compensation of single-phase ground fault current to meet the requirement of reliable arc extinguishing.In this paper,the operating state of ungrounded system and neutral point ground system through passive arc suppression coil was analyzed firstly.On this basis,two simulation models of distribution network system without nonlinear load and nonlinear load were built,and compensation effects of passive arc suppression coil for different ground fault currents were obtained.In order to improve the utilization of the measuring system,a method is proposed to connect the two ends of arc suppression coil at neutral point with specific resistance.Then the simplified circuit model of single-phase grounding fault system was constructed to analyze the source and characteristics of each current component in ground fault,and the calculation and extraction method of active current and harmonic current component which could notbe compensated by passive arc suppression coil was studied,and the simulation verification was carried out.Second,based on the accurate calculation of each current component in single-phase ground fault current,an integrated arc suppression system with passive arc suppression and active arc suppression was proposed aiming at the characteristics of fault current and the deficiency of traditional passive arc extinction method to complete the derivation of the specified current output from the integrated arc extinguisher.In order to realize the comprehensive arc suppression,the control system model of active arc suppression device in the integrated arc suppression system was established,and the DC side voltage stability control and the three-phase bridge arm output current following control algorithm in the active arc suppression device were deduced to realize the design of the whole integrated compensation system.Finally,the simulation model of distribution network with nonlinear load was built in MATLAB/Simulink,and the performance of the integrated arc suppression control system and the effectiveness of the arc suppression were verified.The results show that the design of the control system was accurate and the effects of arc suppression was remarkable.At the same time,the simulation model was compared with the traditional method,indicating that the integrated arc suppression system has the advantages of faster response and smaller fault residual flow. |
PDF Full Text Request