Analysis And Application Of Intelligent Processing Device Of The Single-phase Grounding Fault In Distribution Network

The intelligent processing device of single-phase grounding fault in distribution network intends to solve the faulty line and faulty phase selection of the distribution network,to judge the properties of single-phase grounding fault,to govern the arc grounding overvoltage and ferromagnetic resonance overvoltage.Device has now been operating in Henan Luohe Electric Power Supply Bureau,Jiangxi Ganxi Power Supply Bureau.Improving the structure and function of the device according to the operating situation is an important task after the completion of the device development.Fault phase selection,arc grounding overvoltage government and Information interactive function are key technologies in the application of the device.In this paper,these questions were in-depth study,to improve the device’s capacity of the fault phase selection and the arc grounding overvoltage governance.This paper proposed an adaptive fault phase selection method based on neutral point voltage by analyzing the effect of transition impedance on the amplitude of three-phase voltage and neutral point voltage.Two phase selection criteria are adopted: the lowest voltage amplitude is the fault phase;the next phase of the maximum phase is the fault phase.The reliability of the criterion is depended on the value of the transition impedance,and the magnitude of the neutral point voltage can reflect the magnitude of the transition impedance.The device can choose the high reliability criterion according to the amplitude of the neutral point voltage.According to the governance of the arc grounding overvoltage,this paper puts forward applicating the fault current transfer method to suppress the arc grounding overvoltage by extincting the arc rapidly and reliably.To avoid tripping the line and ensure the reliability of power supply,the device transfers the fault current again.Taking Jiangxi Xinyu shatu transformer substation as an example,the man-machine interface of the device has been optimized and designed,and the communication function has been improved.The fault phase selection method based on neutral point voltage has been tested on the distribution really value test network.The results of the tests show that the phase selection method can accurately identify the fault phase of the single-phase grounding through transition impedance,and the selected phase accuracy is not affected by the system capacity.The capability of the device to govern the arc grounding overvoltage has also been verified by field contrast test between the arc suppression and the device.The experimental results show that the device can suppress the arc grounding overvoltage effectively by extincting the arc quickly and reliably.The practice shows that the device has good information exchange function.The device can communicate with the backstage stably and reliably.The reliability of the operation of the device and its ability to adapt to the distribution network has been improved a lot by optimizing the phase selection method and the arc suppression method of the device.