A semi-controlled active injection current type high-voltage DC circuit breaker and its realization method

Abstract

The invention relates to a breaker of a direct current system, in particular to a semi-controlled active injection current high voltage direct current breaker and a realization method thereof. The breaker comprises a high speed switch-thyristor module branch, as well as a lightning arrester branch and a bridge circuit which are connected in parallel with the branch, wherein a capacitor-reactor series branch and a resistor-thyristor series branch are connected in parallel and then connected with middle points of two bridge arms of the bridge circuit; and the two ends of a capacitor are connected in parallel with a charging loop. The breaker is based on a direct current breaking principle by the traditional active injection current manner; semi-controlled power electronic devices are added; a high speed mechanical switch is adopted; the advantage of low loss during normal breakover is kept; and bidirectional current can be broken quickly without an arc. The breaker is simple in circuit topological structure, simple and convenient to control, mature in technology, easy to realize, great in current breaking capability, high in withstand voltage level and strong in expansion capability, and the cost is lowered greatly since the number of the adopted power electronic devices is small.

Description

technical field [0001] The invention relates to a circuit breaker of a direct current system, in particular to a semi-controlled active injection current type high-voltage direct current circuit breaker and a realization method thereof. 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 ci...

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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; one is a combination of mechanical switches and power electronic devices. The mechanical switch conducts the current during operation, and breaks the mechanical switch when it fails, and uses the generated arc voltage 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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