A hybrid high-voltage direct current circuit breaker and its realization method

Abstract

The invention discloses a hybrid high-voltage direct current circuit breaker and its realization method. The direct current circuit breaker is connected in series in the direct current system, and specifically includes the on-state branch, the pre-transfer branch, the re-transfer branch and the energy consumption branch connected in parallel. branch; the on-state branch comprises at least one fast mechanical switch connected in series and a first current transfer module comprising a fully controlled device; the pre-transfer branch comprises a first inductance connected in series, a first semi-controlled device thyristor series module and a module comprising The second current transfer module of the full-control device; the re-transfer branch includes the second inductance connected in series, the thyristor series module and the capacitor of the second half-control device; the energy consumption branch is composed of a non-linear resistor. The implementation method of the DC circuit breaker includes corresponding operations when the DC system operates normally and when a short-circuit fault occurs. On the premise of ensuring sufficiently fast breaking speed and low loss, the invention adopts a semi-controlled device thyristor, has large breaking current capacity, high withstand voltage level, and greatly reduces the cost.

Description

technical field [0001] The invention relates to a circuit breaker and its realization method, in particular to a hybrid high voltage direct current circuit breaker and its realization method. 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 circuit breaker technology. 1) LC resonant DC circ...

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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 of the arc-breaking 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. The mechanical switch passes the current during normal operation, and breaks the mechanical switch 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 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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