Converter valve, direct current power transmission system and overvoltage protection circuit for converter valve

The invention belongs to the technical field of high-voltage direct-current power transmission, and particularly relates to a converter valve, a direct-current power transmission system and an overvoltage protection circuit for the converter valve. The circuit comprises a plurality of overvoltage protection modules, each overvoltage protection module comprises a voltage comparator, a sampling branch and a first current limiting branch, and the inverted input end of each voltage comparator is used for being connected with one end of a certain switching device on a bridge arm of a converter valve through the corresponding sampling branch. The inverted input end of the voltage comparator is also connected with the damping circuit of the switching device through a first current limiting branch; the in-phase input end of the voltage comparator is connected to reference voltage, and the output end of the voltage comparator is used for being connected with the control electrode of the switching device. By adopting t