Device and method for inhibiting direct current of neutral point of transformer

Abstract

The invention discloses a device for inhibiting the direct current of a neutral point of a transformer and an operating method thereof. The device comprises an automatic switching device connected with the neutral point of the transformer, wherein the automatic switching device is connected with a main earthed network and an independent earthed electrode respectively; the neutral point of the transformer is connected with the main earthed network by an overvoltage isolation device; a direct current monitoring device for acquiring a real-time value of the direct current communicates with the automatic switching device through a serial port or network interface; and the independent earthed electrode at least comprises two types of earthed resistance value ranges. The device has the advantages of avoiding adding a current limiting device, along with easy implementation, high reliability and good direct current limiting effect.

Description

technical field [0001] The invention relates to a device and method for suppressing the neutral point direct current of a transformer. It belongs to the technical field of power transmission and transformation. Background technique [0002] When the DC transmission system operates on the single pole ground return line, the ground current of the DC ground electrode generates a current field, and the surface potential near it is distributed in a gradient drop from the starting point of the ground pole. The neutral point DC potential of transformers in different geographic locations in the area There is a difference. Part of the DC current is formed by the neutral point of the transformer, the winding, the overhead line, and the earth, causing the transformer to generate a DC bias, resulting in a sharp increase in the excitation current and harmonics of the transformer, increased loss and temperature rise, and increased noise and vibration. The greater the DC current flowing t...

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Problems solved by technology

In order to reduce the DC current flowing into the neutral point of the transformer and reduce the adverse effect of DC bias on the transformer, some domestic and foreign methods use a method of connecting a resistor or capacitor in series between the neutral point of the transformer and the earth, but the resistance value of the series connection device The range is not easy to determine, and the failure rate is high, the cost is high, and the maintenance task is heavy; some use the reverse current compensation method, but the compensation device is complicated, the one-time investment is large, and the compensation capacity is easily affected by the change of the grid structure

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