Transformer neutral point capacitance type DC blocking device

Abstract

The invention discloses a transformer neutral point capacitance type DC blocking device which comprises a capacitor set, a resistor, a mechanical by-pass switch, a thyristor valve, an electric reactor, a controller, an AC current transformer and a DC current transformer. The thyristor valve and the electric reactor are connected in series to form a quick bypass circuit. A circuit which is formed by the way that the capacitor set and the resistor are connected in series, the quick bypass circuit and the mechanical by-pass switch are connected in parallel to form an entire structure, one end of the entire structure is connected with a wire inlet end, and the other end of the entire structure is connected with the AC current transformer and the DC current transformer in series to be connected with a wire outlet end. The controller is used for receiving signals collected by the DC current transformer and the AC current transformer, and the controller has the functions of detection, control protection and communication. By means of the transformer neutral point capacitance type DC blocking device, the direct current can be isolated, the direct current and the alternating current can be monitored, the DC isolating mode and the ground protection mode can be switched through a thyristor switched capacitor, the vibration and the transient state peak current and voltage cannot happen to the circuits in the switching process, switching is quick, and the electric power system requirement can be met.

Description

technical field [0001] The invention relates to a transformer neutral point DC blocking device, in particular to a transformer neutral point capacitive DC blocking device. Background technique [0002] When the HVDC power transmission system operates in the single-pole ground mode, there is a DC current flowing into the AC transformer from the ground through the directly grounded neutral point near the DC ground pole, causing the DC bias problem of the transformer, causing transformer noise, vibration and acceleration. Large, affecting the normal operation of the transformer. The transformer neutral point capacitive DC blocking device uses a capacitor device at the transformer neutral point to achieve the purpose of isolating DC current. Due to the high voltage requirements, a large enough capacitance value can meet the requirements, which is difficult to achieve. It is often realized by using lower voltage capacitors and perfect control and protection functions. Capacitiv...

AI Technical Summary

Problems solved by technology

[0002] When the HVDC power transmission system operates in the single-pole ground mode, there is a DC current flowing into the AC transformer from the ground through the directly grounded neutral point near the DC ground pole, causing the DC bias problem of the transformer, causing transformer noise, vibration and acceleration. Large, affecting the normal operation of the transformer

The capacitive DC blocking device at the neutral point of the transformer uses a capacitor device at the neutral point of the transformer to achieve the purpose of isolating DC current. Due to the high voltage requirements, a large enough capacitance value can meet the requirements, which is difficult to achieve.

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