Online fault monitoring device for cable connector in 10-35kV power distribution network and method for evaluating system state

Abstract

The invention discloses an online fault monitoring device for a cable connector in a 10-35kV power distribution network. The online fault monitoring device comprises two current sensors, a difference module, an A/D convertor, a lower computer and a power supply module, wherein the two current sensors are mounted at the two ends of the cable connector in the 10-35 kV power distribution network; pulse current signals received by the current sensors are processed by the difference module to obtain induced voltage signals at the two ends of the cable connector, the induced voltage signals are converted into digital signals through the A/D convertor, and the digital signals are processed by the lower computer to obtain the insulation condition data of the cable connector. The invention further discloses a method for evaluating the system state of the online fault monitoring device for the cable connector in the 10-35kV power distribution network. The method adopts two rogowski coils for high-frequency electromagnetic coupling to respectively collect partial discharge pulse signals, so that the possibility of difference processing on the partial discharge signals of the cable connector is provided. After the signals are subjected to the difference processing, the partial discharge pulse signals can be amplified without distortion, interference signals from the outside can be effectively shielded, and the field interference is effectively restrained.

Description

technical field [0001] The invention belongs to the technical field of on-line monitoring of insulation states, and in particular relates to an on-line fault monitoring device for cable joints in a 10-35kV distribution network. The invention also relates to an online fault monitoring and state evaluation system for cable joints in a 10-35kV distribution network. Background technique [0002] With the sharp increase in the application range and number of XLPE insulated cables in power systems, the insulation problem of XLPE insulated cables has also attracted people's attention. The XLPE power cable line is protected by the XLPE insulated cable body. Generally, there will be no problem with the insulation performance. However, when one cable is not enough for the total length of the line, the joints where the two cables are connected, or when the voltage level and accessory structure are different. When connecting, the insulation problem of the line is more likely to occur. ...

AI Technical Summary

Problems solved by technology

However, the structure is more complicated, the installation is inconvenient, and the scope of application is small

[0005] (3) The electromagnetic coupling method is susceptible to external electromagnetic interference, and it is difficult to exclude some interferences similar to partial discharge pulses simply by relying on broadband filters and high-multiplier amplifiers

[0006] (4) Although the capacitive coupling method has high sensitivity, the attenuation of high-frequency signals is much heavier than that of low-frequency signals. The sensor needs to be built-in, and the scope of application is small

[0007] (5) The measurement frequency of the inductive coupling method can reach very high, but the high-frequency signal attenuation is serious, and the metal shield of the tested cable is required to be wound in a spiral ribbon shape, and the scope of application is small

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