High-voltage DC breaker and control method thereof

Abstract

The invention discloses a high-voltage DC breaker and a control method thereof. The high-voltage DC breaker comprises an on-state current branch, a breaking current branch, and a bridge branch. The on-state current branch is formed by a mechanical switch and a current transfer module provided with a fully-controlled device and guarantees low-on-state loss in a normal on state. The breaking current branch is formed by a nonlinear resistor and a fully-controlled device series valve group which are connected in parallel. The bridge branch comprises two bridge arms formed by four same commutation modules. Each commutation module is formed by an uncontrolled device series valve group and an inductor which are connected in series. The bridge branch enables the breaking current branch to be capable of breaking bidirectional bidirectional line current and reduces the number of fully-controlled devices and equipment cost.

Description

technical field [0001] The invention relates to a high-voltage direct current circuit breaker, and also relates to a control method of the high-voltage direct current circuit breaker, which belongs to the technical field of circuit breakers. Background technique [0002] With the development of multi-terminal DC transmission technology, high-voltage DC circuit breakers will become one of the key equipment to ensure the safe and stable operation of the system. Due to the high voltage level and small line impedance of the multi-terminal HVDC transmission system, once a line short-circuit fault occurs, it will quickly affect the DC transmission network and the AC network, and the fault must be removed quickly. Therefore, the high-voltage DC circuit breaker needs to operate quickly, which can minimize the fault duration or suppress the fault current, and reduce the impact of the fault on the AC / DC transmission network. [0003] At present, there are usually three methods of DC ...

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Problems solved by technology

[0003] At present, there are usually three methods of DC circuit breaker technology. 1) LC resonant DC circuit breaker: on the basis of conventional AC mechanical circuit breakers, by adding auxiliary circuits, superimposed increased oscillating current on the DC current that breaks the arc gap, using Break the circuit when the current crosses zero. The mechanical circuit breaker manufactured by this principle cannot meet the requirements of the multi-terminal flexible DC transmission system in terms of breaking time and breaking current capacity; Breaking power electronic devices directly breaks the DC current. Although the solid-state circuit breaker manufactured by this principle 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; 3 ) Hybrid DC circuit breaker: It adopts a hybrid method of mechanical switches and power electronic devices. During normal operation, the mechanical switch passes the current, and the mechanical switch is broken when a fault occurs. The generated arc voltage is used to transfer the current to the branch circuit of the power electronic devices connected in parallel. , and then the current is broken by the power electronic device

Based on this principle, the circuit breaker not only reduces the on-state loss, but also improves the breaking speed, but it needs to break the line current in two directions. High, resulting in expensive DC circuit breaker equipment, affecting its wide application and promotion

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