Capacitance DC (Direct Current) blocking on-off controllable bridge circuit for inhibiting DC magnetic bias of transformer

Abstract

The invention relates to a capacitance DC (Direct Current) blocking on-off controllable bridge circuit for inhibiting DC magnetic bias of a transformer, which is characterized by comprising a bypass ground loop, a transformer neutral wire earthing switch K1, a DC blocking switch K 2, a DC blocking capacitor C and a transient current inhibiting bridge circuit. Compared with a conventional capacitance DC blocking circuit, the capacitance DC blocking on-off controllable bridge circuit utilizes a DC inductance in the transient current inhibiting bridge circuit to limit the rising change rate of a short circuit current on the initial stage of system failure, does not need to control system response and adopts an instantaneous automatic switching mode, so that the capacitor is avoided being impacted and damaged by a transient current, a neutral point of the transformer is guaranteed to be effectively grounded and a control system has sufficient response time to switch working modes; addition of the transient current inhibiting bridge circuit has no any influence on an AC (Alternate Current) loop in the normal operating process; a DC component can be well inhibited from flowing into the transformer; the DC magnetic bias of the transformer is effectively inhibited; safety of the system is ensured; and the capacitance DC blocking on-off controllable bridge circuit has the advantages of simple structure of a control circuit, convenience for implementation, reliable performance, small size, low price and the like.

Description

technical field [0001] The invention relates to a capacitive DC-blocking controllable breaking bridge circuit for suppressing the DC bias of a transformer, and belongs to the technical field of safe operation of high-voltage equipment in a power system. Background technique [0002] When the HVDC power transmission operates in the single-pole ground loop mode, the DC bias phenomenon occurs in the transformer. This mode of operation will cause a high DC current to flow from the ground pole of the DC transmission system to the earth, and flow into the transformer winding from the grounded neutral line, causing the transformer to generate DC bias. The DC bias will bring a lot of damage to the transformer. For example, the noise increases due to the aggravation of vibration, the increase of loss due to the deepening of saturation, the increase of temperature causes local overheating, and the generation of a large number of harmonics leads to protection malfunctions, etc. [000...

AI Technical Summary

Problems solved by technology

Even if the design parameters of the capacitor are considered, the safety of the capacitor cannot be fully guaranteed. Once the capacitor is damaged, the grounding mode of the neutral point of the transformer will change, which will affect the correct operation of the relay protection and other issues.

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