Fault phase judgment and wire selection method by using phasor product active method

Abstract

The invention discloses a fault phase judgment and wire selection method by using a phasor product active method. Phasor product active power is equal to the average value of a half cycle of a productof synchronous sampling values of two phasors, and a phase relation between the phasors is judged according to the size and plus or minus of the phasor product active, so that the judgment and wire selection of the fault phase when a single phase is grounded are achieved, judgment is not longer performed depending in accurate computation of each fault quantity, the accurate computation of the fault quantity by Fourier transform is not needed, the influences of various uncertain factors and transient state quantities are avoided, the fault phase and wire selection are accurately judged, and the safe running of the system is ensured.

Description

technical field [0001] The invention relates to a neutral point non-effective grounding system of a power grid, in particular to the identification and line selection of a faulty phase when a single-phase grounding fault occurs. Background technique [0002] For a long time, the neutral point ungrounded method is the most widely used grounding method in my country's distribution network. It has low investment and high power supply reliability. However, when arcing grounding occurs in this system, since the energy in the grounding capacitor cannot be effectively released, arcing grounding overvoltage or resonance overvoltage will occur, and the value of this voltage is very high, which will cause damage to the insulation of electrical equipment in the system threaten. [0003] At present, the arc suppression coil and the fault phase grounding arc suppression have defects, and the neutral point low-value resistor grounding has to be used to quickly cut off the fault line, but...

AI Technical Summary

Problems solved by technology

However, when arcing grounding occurs in this system, since the energy in the grounding capacitor cannot be effectively released, arcing grounding overvoltage or resonance overvoltage will occur, and the value of this voltage is very high, which will cause damage to the insulation of electrical equipment in the system threaten

[0003] At present, the arc suppression coil and the fault phase grounding arc suppression have defects, and the neutral point low-value resistor grounding has to be used to quickly cut off the fault line, but the neutral point is grounded through a low-value resistor and is grounded with high impedance at the fault point Time failure, also can not cut off the faulty line

[0004] The arc suppression of fault phase grounding is simple and saves investment, but it is difficult to judge the fault phase. If the fault phase cannot be accurately judged, it will cause short circuit between phases, which not only fails to suppress arc, but also causes greater accidents. must-have conditions

[0005] The inability to accurately select the line for single-phase grounding is a common problem of all current line selection devices. The inability to accurately select the line and judge the fault phase is because the process of arc light grounding arc ignition and arc extinguishing is very complicated. The current algorithm for line selection and judgment of the fault phase is Start with the accurate calculation of the value of each fault quantity, quantitatively judge the fault and select the line, because there are too many uncertain factors in the arcing process of the arc grounding arc, the arcing period is often less than half a cycle, and the arcing and arcing period The voltage is the phase voltage and the voltage to the ground respectively, not a voltage parameter, and precise calculation algorithms such as Fourier transform are useless. Coupled with the influence of transient quantities, the existing technical means can not get satisfactory results.

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