Study On Characteristics Of Grounding Mode Of Neutral Point Through Arc Suppression Coil With Parallel Resistor In 10kV Distribution Network

With the acceleration of China's urbanization process,China's power distribution system has developed rapidly in recent years.The distribution system has the characteristics of wide distribution area,complex structure and frequent random faults.The neutral point grounding method plays a decisive influence on the fault detection and processing and the operation of the distribution network.But the grounding mode of distribution network has always been a controversial topic at home and abroad.At present,there are many kinds of low current grounding modes,but the accuracy of line selection is relatively low.The new type of low current grounding mode with parallel resistance of arc suppression coil can solve the problem that the existing grounding mode of distribution network can not take both arc suppression and fast line selection tripping into account.Firstly,the characteristics of single-phase grounding fault in distribution network and various grounding modes are analyzed,including neutral point non-grounding,neutral point grounding through arc suppression coil,neutral point grounding through resistance and so on.A new grounding method with neutral point through arc suppression coil with parallel resistor is proposed.The advantages of the new grounding method compared with other grounding methods are analyzed,and the ground fault characteristics are simulated and verified.Then,the paper analyzes the basic principle of the grounding method and the system voltage and current when transient ground fault and permanent ground fault occur,including transient and steady state conditions,and verifies the feasibility of the grounding method.Then,this paper systematically analyzes the principle of small current grounding line selection of arc-suppression coil with parallel resistor,and obtains the criterion of fault line selection.Through the establishment of the grid simulation model,the variation of the zero-sequence voltage of the faulty and non-faulty lines under zero-sequence current and zero-sequence current and the zero-sequence voltage of the system before and after the parallel resistance are simulated.The characteristics of the small current ground fault line selection method for the arc suppression coil with parallel resistor are analyzed,and its superiority in fault line selection is proved.Finally,some important characteristics of arc suppression coil with parallel resistor in low current grounding mode are studied and simulated in detail,including the theoretical analysis of the relationship between parallel resistor and system parameters,the transient impact of parallel resistor switching on system voltage,and the ability of parallel resistor switching time to suppress arc grounding overvoltage.