DC magnetic bias current suppression device for transformer high-voltage winding

Abstract

The invention provides a DC magnetic bias current suppression device for a transformer high-voltage winding. The suppression device comprises a bypass protection device, a measuring device and a control device, and is characterized in that the bypass protection device comprises a clearance and a bypass switch, and the clearance and the bypass switch are connected in parallel and then connected to a transformer neutral point in series; the measuring device is used for measuring voltage at both ends of the bypass switch and current flowing through the bypass switch; the control device compares the voltage and the current, which are measured by the measuring device, with preset operation voltage and preset operation current respectively; when the current exceeds the operation current, the bypass switch is disconnected; and when the voltage is lower than the operation voltage, the bypass switch is closed. The suppression device provided by the invention can effectively suppress influences imposed on a transformer with the transformer neutral point being directly grounded by DC grounding electrode earth current. The suppression device is simple in structure, small in size, convenient to install and less in capital investment, does not change a grounding mode when the transformer is in normal operation, and has no influence for line protection.

Description

technical field [0001] The invention relates to a suppressing device for DC bias current of transformer high-voltage winding. Background technique [0002] In recent years, with the rapid economic development and the rapid growth of energy demand, long-distance and large-capacity DC transmission projects have developed rapidly. my country's land resources are tight, and the grounding electrodes of DC transmission projects are very close to the AC substations in many places. The transformers of AC substations are inevitably affected by the ground current of the DC grounding electrodes. When the unipolar DC line runs with the ground as the loop, the huge DC current forms the loop with the ground, and the flow through the ground will affect the nearby AC system. When unipolar or bipolar operates with the earth as the loop, a potential difference will be formed between the AC substations, and the DC current will flow through the transformer winding through the neutral point of ...

AI Technical Summary

Problems solved by technology

The series impedance of the neutral point has an impact on the zero-sequence parameters of the system, which in turn will also affect the setting of the relay protection

The disadvantage of this scheme is that it cannot completely offset the inflow of DC from the neutral point, but because of its clear concept, it is relatively easy to implement and has little impact on the system

[0007] The devices involved in the reverse direct current and potential compensation method are complex and difficult to realize, and there is no application at this stage

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