Transformer neutral point direct current suppression device

Abstract

The invention discloses a transformer neutral point direct current suppression device. The transformer neutral point direct current suppression device comprises a blocking capacitor connected between a neutral point of a transformer and the ground, a rapid closing switch in parallel connection with the blocking capacitor, a rectifier bridge and a triggering module. The input end of the rectifier bridge is connected with the two ends of the blocking capacitor and enables an alternating current voltage of the neutral point of the transformer to be converted into a direct current voltage, and the direct current voltage is output to the triggering module. The output end of the triggering module is connected with a trip coil of the rapid closing switch and used for detecting the value of a voltage output by the rectifier bridge in time, when an over-voltage is detected, the triggering module is triggered and switched on so as to enable the trip coil to be powered on, the normally open contact of the rapid closing switch is closed rapidly, at the moment, the blocking capacitor is short-circuited by the rapid closing switch, and the neutral point of the transformer is connected with the ground through the rapid closing switch and retreats from the blocking capacitor automatically. The transformer neutral point direct current suppression device can prevent a direct current from flowing into the alternating current transformer, therefore, the neutral point of the transformer is protected, and the capacitor of the device is also protected; the reliability of the device is improved, and further expansion of power grid accidents is avoided.

Description

technical field [0001] The invention relates to the technical field of electric power system voltage automatic control, in particular to a neutral point direct current suppression device of a transformer, which functions as a device for protecting capacitors and preventing overvoltage at the neutral point of the transformer. Background technique [0002] At present, with the development of UHV DC transmission technology, more and more UHV DC transmission lines are put into operation, and the impact of UHV DC transmission on AC systems is becoming more and more obvious. One of the main effects is that when the DC transmission line operates with a single pole or a two-phase unbalanced operation, the ground will be used as a current return loop. At this time, a part of the DC current will flow into the AC system through the AC transformer with the neutral point grounded. After DC flows into the AC transformer, the transformer will generate a DC bias phenomenon, which will affec...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a transformer neutral point DC current suppression device, which can realize that when the device is completely de-energized and overvoltage occurs at both ends of the capacitor, the device can still automatically withdraw from the capacitor to protect the capacitor and prevent the neutral point of the transformer. The effect of point overvoltage can reliably solve the problem of transformer DC bias

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