Topological structure of hybrid direct-current circuit breaker and control method thereof

Abstract

The invention discloses a topological structure of a hybrid direct-current circuit breaker and a control method thereof. Three groups of diodes are introduced into the topological structure; current-limiting inductors are divided into two parts evenly and the two parts of current-limiting inductors are installed at the two ends of a circuit breaker; and an IGBT with an anti-parallel diode is introduced. The direct-current circuit breaker is composed of a mechanical switch branch, a diode group including diode bridge arms D1 to D4 and a ground diode group D5, a solid-stage switch branch formedby series connection of sub modules, voltage-limiting energy absorption branches connected in parallel at the two ends of the solid-stage switch branch, a T1 arranged between the solid-stage switch branch and the diode bridge arms D1 and D2, and an IGBT with an anti-parallel diode for cooperating with a quick mechanical switch to carry out closing. On the basis of the topological structure disclosed by the invention, the total time of fault current cutting is reduced effectively, the short-circuit fault cutting is accelerated; the requirement on the through-flow capacity of the lightning arrester is reduced; and a problem of cooperative usage of the disconnecting switch during the closing operation of the circuit breaker is solved.

Description

technical field [0001] The invention relates to the field of electrical technology, in particular to a hybrid DC circuit breaker topology and a control method thereof. Background technique [0002] Compared with AC transmission, HVDC transmission has the advantages of low transmission line construction cost, simple and easy power regulation, and no stability problems, and is suitable for ultra-high voltage, large-capacity, and long-distance transmission. The damping of the DC system is low. Compared with the AC system, the control and protection of the DC system is more difficult, and for the flexible DC transmission system based on fully controlled semiconductor devices, the ability of the device to withstand overcurrent is weak, and the fault current It may exceed the highest tolerance value of the device within a few milliseconds, causing damage to key devices and even the entire converter station. Therefore, it is necessary to quickly limit and cut off the fault current ...

AI Technical Summary

Problems solved by technology

The typical scheme is proposed in the article "Design Scheme of New HVDC Circuit Breaker for Flexible DC Transmission Network" (author Wei Xiaoguang, etc.) published in the journal "Power System Automation", Volume 37, Issue 15, Pages 95-102 in 2013 The topology scheme, as shown in Figure 3(a), Figure 3(b)-Figure 3(c) It is the topological structure diagram of the two sub-modules in the existing scheme. This scheme converts the series dynamic voltage equalization problem of a large number of IGBTs into the voltage equalization of the sub-module capacitors. According to the existing technology, it is relatively easy to realize in engineering technology, and the disadvantage is that it uses electric power The number of electronic components is large, the cost is high, the volume is large, the fault current cut-off speed is slow, and there are problems in the use of the isolating switch during the closing operation

[0006] To sum up, the hybrid DC circuit breakers in the prior art, especially the forced commutation hybrid DC circuit breakers composed of cascaded sub-modules in the solid-state switch branch, have a slow fault removal speed, and the closing operation is different from There are shortcomings such as problems in the use of isolating switches, and there is still no effective solution for this

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