A DC Bias Magnetic Isolation and Grounding Device Based on Capacitor Communication and DC Blocking

Abstract

The invention provides a capacitive AC conducting and DC blocking-based DC bias isolation grounding device, which comprises a DC bias isolation system and a fault detection system, wherein the DC bias isolation system comprises a capacitor connected with a neutral point of an AC power transmission transformer in series, a high-speed vacuum circuit breaker, a zinc oxide nonlinear resistor voltage limiting protector assembly and an intelligent monitoring device for controlling the high-speed vacuum circuit breaker to run, wherein the high-speed vacuum circuit breaker and the zinc oxide nonlinear resistor voltage limiting protector assembly are connected with the capacitor in parallel; and the fault detection system is connected with the DC bias isolation system and is used for carrying out real-time fault monitoring on the DC bias isolation system. A DC bias function is achieved through the DC bias isolation system; and the corresponding fault detection system is arranged, so that health information of various devices in the DC bias isolation grounding device can be monitored in real time to be processed in real time when one device is broken down; the safety performance is high; and the construction cost is low.

Description

technical field [0001] The invention relates to the technical field of transformer protection, in particular to a DC bias isolation and grounding device based on capacitor communication and DC isolation. Background technique [0002] Due to the implementation of DC transmission by the State Grid, in the process of AC-DC hybrid transmission, when the DC transmission line adopts single-pole operation, the ground pole current flows into the neutral point grounding circuit of the AC system transformer, resulting in DC bias, oscillation and noise of the transformer. , temperature rise and other phenomena seriously cause transformer magnetic saturation, AC sine wave waveform distortion, and harmonic increase, which pose a serious threat to the safe production of the power system. [0003] The solutions in the related art include the series resistance method, the series capacitance method, and the reverse current injection method. The above-mentioned methods must consider the overv...

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Problems solved by technology

[0002] Due to the implementation of DC transmission by the State Grid, in the process of AC-DC hybrid transmission, when the DC transmission line adopts single-pole operation, the ground pole current flows into the neutral point grounding circuit of the AC system transformer, resulting in DC bias, oscillation and noise of the transformer. , temperature rise and other phenomena, which seriously cause transformer magnetic saturation, AC sine wave waveform distortion, and harmonic increase, which pose a serious threat to the safe production of the power system

[0003] The solutions in the related art include the series resistance method, the series capacitance method, and the reverse current injection method. The above-mentioned methods must consider the overvoltage problem at both ends of the series device of the transformer when a single-phase ground asymmetrical short-circuit fault occurs, and because the parallel connection Over-voltage protection components, the current-through capacity of the transformer is relatively weak, so the above-mentioned solutions are acceptable for small short-circuit currents. For large-capacity giant transformers with a peak value of short-circuit current of tens of kiloamperes or even hundreds of kiloamperes, it is necessary to improve the series connection The withstand voltage level of the device is high; in addition, the DC bias isolation and grounding device in the related art lacks a corresponding fault detection system, and cannot monitor the health information of each device in the DC bias isolation and grounding device in real time, so that it cannot When a fault occurs, corresponding processing is performed, and the safety performance is low

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