A hybrid power switch and its application in a flexible DC transmission converter

Abstract

The invention discloses a hybrid power switch and its application in a flexible direct current transmission converter. The hybrid power switch is composed of a fast-isolated mechanical switch and a bidirectional power electronic switch connected in series and connected in parallel with a power electronic switch with an anti-parallel diode. Composed of switches, it has the advantages of low conduction loss of mechanical switches and good switching characteristics of power electronic devices. The sub-modules that the hybrid power switch can be applied to include but are not limited to full-bridge sub-modules, self-resistance sub-modules, half-bridge and full-bridge hybrid sub-modules, twin-clamp sub-modules, interleaved sub-modules and the above-mentioned sub-modules. A mix of modules with other submodules that do not have fault handling capabilities. The MMC topology containing hybrid switches can limit the DC short-circuit current by blocking sub-modules or generating negative levels, reducing the requirements of the DC power grid on the response speed and breaking capacity of the DC circuit breaker, thereby reducing the manufacturing difficulty and production cost of the DC circuit breaker.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a hybrid power switch and its application in a flexible direct current transmission converter. Background technique [0002] Since the advent of Modular Multilevel Converter (MMC) in 2002, it has become increasingly popular in High Voltage Direct Current (HVDC) due to its high modularity, good output waveform quality, and low converter loss. ) is one of the most promising converter topologies in power transmission systems. DC side short-circuit fault is a common fault form in DC transmission, especially overhead line DC transmission. How to quickly and reliably remove DC faults is one of the main challenges for the large-scale application of flexible DC transmission technology. At present, there are three main ways to deal with DC side faults: 1) cut off the connection between the fault and the AC system through AC devices such as AC circuit breakers and A...

AI Technical Summary

Problems solved by technology

However, for the grid-connected DC transmission network, the first method has long response time, large impact on the grid, complicated restart and failure to achieve fault selectivity in the DC transmission network due to the limitation of the AC circuit breaker’s operating characteristics and installation location. resection requirements

The second method is one of the effective solutions to solve the short-circuit fault of the DC power grid, but this solution requires a DC circuit breaker with fast response speed, small conduction loss, and large breaking capacity. The technical difficulty and cost of DC circuit breakers are relatively high. , it is difficult to apply to practical engineering in a short time

[0004] At present, the representative sub-module structure that can realize DC fault protection is the full-bridge sub-module and the clamping twin sub-module structure. However, the loss of the MMC converter valve based on the above two sub-module structures or their combination with the half-bridge sub-module structure is large. increase, seriously restricting its engineering application

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