Flexible straight valve submodule capacitor overvoltage protection device and protection method

Abstract

The invention discloses a flexible straight valve submodule capacitor overvoltage protection device and protection method. The input end of a capacitor voltage conditioning module of the capacitor overvoltage protection device is connected with a capacitor of a flexible straight valve submodule, and the output end of the capacitor voltage conditioning module is connected with a first protection module and a second protection module; the first protection module compares the capacitance voltage value output by the capacitance voltage conditioning module with a first preset voltage value, and when the capacitance voltage value is larger than or equal to the first preset voltage value, the bypass driving unit controls the bypass switch to cut off the flexible straight valve sub-module; the second protection module obtains a capacitance voltage value output by the capacitance voltage conditioning unit, and when the capacitance voltage value is larger than or equal to a second preset voltage value, the bypass driving unit controls the bypass switch to cut off the flexible straight valve sub-module; wherein the second preset voltage value is greater than the first preset voltage value. By adopting the multiple capacitor overvoltage protection devices, the flexible straight valve sub-module is cut off when the capacitor is in overvoltage, and the operation safety of the whole valve system is improved.

Description

technical field [0001] The invention relates to the technical field of power equipment control, in particular to a capacitor overvoltage protection device and protection method for a flexible straight valve sub-module. Background technique [0002] MMC is an important topology of flexible HVDC converter valves, such as Figure 1a or Figure 1b As shown, each sub-module usually adopts a half-bridge or full-bridge structure, and each bridge arm is often composed of dozens or even hundreds of MMC valve sub-modules connected in series. In order to ensure the safe, reliable and normal operation of the flexible straight valve when a faulty sub-module occurs, each sub-module is equipped with a bypass switch. When a serious fault occurs in a sub-module, the faulty sub-module Quick removal, otherwise it will endanger the safe operation of the entire valve system. [0003] Capacitor overvoltage fault is a common and serious fault in the operation of sub-modules. If the protection is...

AI Technical Summary

Problems solved by technology

[0003] Capacitor overvoltage fault is a common and serious fault in the operation of sub-modules. If the protection is not proper, it will cause the IGBT breakdown of the sub-module, resulting in a short circuit at both ends of the capacitor of the sub-module, causing the sub-module to explode or even catch fire, and cause damage to the entire power transmission system. The consequences could be disastrous

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