Detection discrimination method of arc light fault

Abstract

The invention discloses a detection discrimination method of an arc light fault. The method comprises the following steps that: a passive optical sensor is installed in a small chamber of a switch cabinet and arc light signals are identified and obtained continuously by using a light frequency-selecting band-pass thin-film technology; the signals are transmitted to a protection device by a large-core diameter plastic optical fiber or a large-numerical aperture quartz multi-mode fiber; the protection device carries out analog-digital conversion to convert analog optical signals into digital optical signals by a fixed sampling frequency; the digital optical signals are transmitted with high speed between device plate cards and devices by using an IEC 61850 process level technology; and the protection device carries out retrieval matching on the digital optical signals and a preset optical signal grouping logic and whether an arc light fault occurs can be determined comprehensively by combining a power-frequency variation current signal criteria. With the method, the arc light fault existence can be detected rapidly and reliably so as to carry out fault isolation, thereby reducing damages on the equipment and the personnel by the fault.

Description

technical field [0001] The invention relates to a method for detecting and judging arc light faults, which is suitable for fast protection of busbars, transformers, motors and circuit breakers in power grids, power plants, substations of industrial enterprises and the like. Background technique [0002] At present, the medium-voltage systems in my country's power grid structure, that is, 10kV and 35kV levels, mostly use closed central cabinets to lead out with cables. Compared with the gap, the manufacturing quality has declined in recent years, and the probability of short-circuit accidents is relatively high. [0003] The consequence of the bus failure is that the gas generated by it expands rapidly and causes the switchgear to explode; the high temperature of the arc causes the copper bar, aluminum bar, and cable to burn; the switchgear vibrates strongly, causing the fixing parts to loosen; Sound, etc. may cause personal injury. [0004] Since the current relay protectio...

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Problems solved by technology

[0005] 1) The bus fault is cut off by the backup overcurrent protection, considering the setting and coordination, the protection action time is generally more than 1.0s, and the long cut-off time often leads to the development of a more serious fault after the fault occurs. The impact and damage caused by the medium and low-voltage power distribution device itself to the main transformer are very large, and the equipment is damaged to a large extent, or even burned, affecting production and operation;

[0006] 2) The overcurrent protection of the feeder overcurrent element reversely blocks the incoming line, the typical protection action time is 100ms, but the wiring construction is complicated, and the blocking circuit has no monitoring mechanism, so it is impossible to monitor whether the blocking circuit is normal in real time;

[0007] 3) Conventional current differential busbar protection is adopted. This protection principle is widely used in high-voltage busbars of 110kV and above, and the effect is good. The typical protection action time is 30-45ms. It leads to protection malfunction, and the number of branch circuits of the device is difficult to meet the requirements of the outgoing line interval, which limits the application of this type of protection

This type of optical sensor has low manufacturing cost, but it introduces weak electric signals into the strong electric switch chamber, and the weak voltage signals during transmission are susceptible to electromagnetic interference in the installation environment, reducing reliability;

[0010] 2) Some products use passive optical sensors to collect light signals, but the photosensitive effects of the sensors within the 180-degree full field of view directly in front of the light sensors are quite different, which does not match the performance marked in the product manual, which will lead to a narrowing of the monitoring range, or even There will be a monitoring dead zone;

[0011] 3) The electrical quantity auxiliary criterion of the existing products adopts the incoming line current amplitude criterion and the zero-sequence current criterion, and the fault detection speed in some fault cases is slow, which affects the overall performance of this type of protection device

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