A Method for Suppressing DC Bias of Power Transformer

Abstract

The invention discloses a power transformer DC magnetic bias restraining method. The power transformer has three phase inputs and three phase outputs, the power transformer is formed by three primary windings and three secondary windings, third windings are wound on a common iron core of the power transformer and serve as DC compensating windings, the third windings are connected in series with a DC current source controlled by the current, a DC current transformer is installed on a neutral point of the primary windings, three third windings are arranged and are connected in series with one another, and the polarity of the current output by the DC current source is opposite to that of DC through the neutral point of the primary windings of the power transformer. According to the invention, transformer DC magnetic bias is restrained by starting with the internal structure of the transformer body, the cost is relatively low, power transformer DC magnetic bias restraining method has good feasibility, reliability and practicality, and good DC magnetic bias restraining effect can be achieved.

Description

technical field [0001] The invention relates to the technical field of high-voltage power transmission and transformation, in particular to a method for suppressing DC bias of a power transformer. Background technique [0002] With the development of the power system, EHV and UHV DC transmission technologies have been more and more widely used in my country. However, in actual operation, when the EHV and UHV DC transmission systems are operating in single-pole ground loop operation mode or bipolar unbalanced operation mode, it is easy to cause DC bias phenomenon in the transformers of AC substations around the converter station. In addition, the geomagnetically induced current will also cause the transformer to generate DC bias. [0003] Transformer DC bias is manifested as: 1) increased noise; 2) increased vibration; 3) local overheating; 4) distortion of voltage waveform; 5) increased transformer loss. [0004] The existing methods to solve the DC bias of power transform...

AI Technical Summary

Problems solved by technology

However, in order to limit the overvoltage at both ends of the capacitor during the fault process, a large-capacity voltage regulator needs to be installed, which requires a large installation space and is expensive

[0010] The above method 3 can flexibly control the reverse DC current injected into the neutral point according to the magnitude of the DC flow, but the device implementation and control strategy are complex, difficult and expensive

[0011] The above methods all install suppression devices on the neutral point of the transformer, which may lead to changes in the DC current flowing through the neutral point of the transformer at other positions. Governance measures will bring new power grid security problems to varying degrees

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