Small current grounding system single phase earth fault traveling wave line selection and distance measurement apparatus

Abstract

The invention provides a small current grounding system single phase earth fault traveling wave line selection and distance measurement apparatus which comprises a signal conversion plate, a high speed acquisition plate and a central management machine. The signal conversion plate converts bus zero sequence voltage and line current to 0 to 10 volts voltage signal after isolation. The high speed acquisition plate connecting with the signal conversion plate finishes the conversion from analog signal to digital signal, carries out high speed acquisition and caching, receives a synchronization time setting signal simultaneously, and marks data with absolute marker. A digital signal processor (DSP) of the high speed acquisition plate calculates whether the zero sequence voltage exceeds a starting set value or not, wherein, if so, line fault happens. The DSP automatically searches and calculates a tip size and direction of traveling wave, and outputs line selection result through a switch output plate connecting the high speed acquisition plate. Simultaneously wave recording is started to record fault data which is transmitted to the central management machine through a high speed bus. According to the wave recording data, the central management machine automatically searches initial wave tip of the fault line and time of fault point reflection wave tip, and calculates distance of the fault point. Finally, fault data and fault report are published through a WEB SERVER platform.

Description

technical field [0001] The invention belongs to the field of power systems, and relates to a traveling wave line selection and traveling wave distance measuring device for a single-phase grounding fault in a small current grounding system. Background technique [0002] The low-current grounding method for the neutral point of the distribution network has a series of advantages, so it is adopted by the distribution system of many countries. When a single-phase ground fault occurs in a low-current grounding system, since the neutral point is not directly grounded, a short-circuit loop cannot be formed, so there is no short-circuit current, and only a small capacitive current flows to the fault point. However, this situation cannot exist for a long time. On the one hand, the non-fault phase voltage will rise, posing a threat to the line insulation; on the other hand, the arc current at the grounding point will burn the line, causing permanent damage to the line. China's elect...

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Problems solved by technology

[0009] The invention provides a single-phase ground fault traveling wave line selection and distance measuring device for a small current grounding system. Aiming at the current problem of small current ground fault line selection, the hardware technology of high-speed acquisition, high-resolution sampling and high-precision synchronization is adopted, combined with The original fault start discrimination algorithm enables accurate start-up of wave recording after device failure, avoiding the problem that the use of hardware to extract transient disturbance judgment start-up is easily affected by interference signals, and combined with wavelet transform theory to realize the detection of initial traveling waves. After comparison of traveling waves Amplitude, phase and initial time of traveling wave, etc., to obtain the fault line

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