High-voltage DC circuit breaker and realization method thereof

Abstract

The invention relates to a circuit breaker and a realization method thereof, and particularly relates to a high-voltage DC circuit breaker and a realization method thereof. The DC circuit breaker, based on a secondary current transferring principle, comprises a main branch, a current transferring branch and an energy absorption branch in parallel connection. The DC circuit breaker is serially connected in a DC system. The main branch comprises at least one high-speed mechanical switch K and at least one current transferring module comprising a fully-controlled device in serial connection. The current transferring branch is a bridge circuit formed by thyristor valves, inductors and capacitors. The energy absorption branch is formed by a non-linear resistor. The invention also provides a high-voltage DC circuit breaker realization method. The circuit breaker provided by the invention has a simple topological structure, the control is simple and convenient, used power electronic devices are mainly half-controlled thyristors, the technology is mature, realization is easy, the current breaking ability is large, a voltage-withstanding grade is high, the extension ability is strong, and the cost is greatly reduced.

Description

technical field [0001] The invention relates to a circuit breaker and its realization method, in particular to a high-voltage direct current circuit breaker and its realization method. Background technique [0002] With the application of multi-terminal flexible DC and DC grid technology based on voltage source converter (VSC), fast DC circuit breakers have become one of the key equipment to ensure the stable, safe and reliable operation of the system. In the AC system, the AC current has two natural zero-crossing points in one cycle, and the AC circuit breaker uses the natural zero-crossing points of the current to cut off the current, while in the DC system, the DC current does not have a natural zero-crossing point, so the DC current The breaking of the current is much more difficult than the breaking of the alternating current. [0003] There are usually three ways to break the DC current. One is to add an auxiliary circuit on the basis of the conventional AC mechanical...

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Problems solved by technology

[0003] There are usually three ways to break the DC current. One is to add an auxiliary circuit on the basis of the conventional AC mechanical circuit breaker to superimpose the increased oscillation current on the DC current of the breaking arc gap, and use the current to break when the current crosses zero. The mechanical circuit breaker manufactured using this principle cannot meet the requirements of the multi-terminal flexible DC transmission system in terms of breaking time; one is to use high power to turn off power electronic devices and directly break the DC current, using this principle Although the manufactured solid-state circuit breaker can meet the requirements of the multi-terminal flexible DC system in terms of time, the loss is too large during normal conduction, and the economy is poor; the last one is a combination of mechanical switches and power electronic devices. In normal operation, the mechanical switch passes the current, and the mechanical switch is broken in case of failure, and the arc voltage generated is used to transfer the current to the branch circuit of the power electronic device connected in parallel, and then the power electronic device breaks the current

Based on this principle, the circuit breaker not only reduces the on-state loss, but also increases the breaking speed, but it needs to use a large number of fully-controlled devices in series, which is difficult in technology and high in manufacturing costs. At its peak, its cost will nearly double

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