A transformer DC bias current suppression device and control method

Abstract

The invention discloses a suppression device for direct-current biasing current of a transformer and a control method. The device comprises a nonlinear positive temperature coefficient (PTC) thermistor, a zinc oxide resistor, controlled-clearance dual-ball electrodes, a current sensor, a voltage sensor, a digital monitor and a remote monitoring system, wherein the zinc oxide resistor is connected with the nonlinear PTC thermistor in parallel and is used for protecting the nonlinear PTC thermistor and preventing over-high voltage of a neutral point of the transformer; and the distance between the controlled-clearance dual-ball electrodes can be adjusted and set according to the requirements. The suppression device is simple in structure, small in size, convenient to install and relatively low in fund input; control equipment is not needed; the grounding mode when the transformer normally runs is not changed; the control method for the device has the characteristic of being simple to operate, and essentially has no influence on circuit protection; and the short circuit current of the circuit can be effectively reduced.

Description

technical field [0001] The invention relates to power grid operation control technology, more specifically, to a transformer DC bias current suppression device and control method. 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. 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 the single pole 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 the transformer and the transmission line, causing the transformer to appear magnetically biased. In the AC power grid, if the neutral point directly grounded transformer works in the saturation region of the exc...

AI Technical Summary

Problems solved by technology

[0006] (3) Transformer copper loss increases,

[0007] (4) Transformer iron loss increases,

[0008] The impact of DC grounding current on substation transformers has the following characteristics: uncertain time (occurs during fault or maintenance), short action time (several hours), large amplitude of grounding current (thousands of amperes), positive and negative polarity Uncertain, the characteristics that have a great influence on the transformer

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