Converter valve bridge arm submodule with overvoltage suppression function, control method thereof and converter valve

Abstract

The invention discloses a converter valve bridge arm submodule with an overvoltage suppression function. The converter valve bridge arm submodule comprises a power circuit and an overvoltage suppression circuit, the source electrode of the first power device is connected with the drain electrode of the second power device, and the first bypass switch is connected in parallel with the second power device and the connection port of the converter valve single-bridge arm submodule; the anode of the first lightning arrester is connected with the drain electrode of the first power device and one end of the DC capacitor and one end of the voltage-sharing resistor, and the cathode of the first lightning arrester is connected with the anode of the second lightning arrester. The negative electrode of the second lightning arrester is connected with one end of the DC capacitor, one end of the voltage-sharing resistor and the source electrode of the second power device. And the second bypass switch and the third power device are connected in parallel with the second lightning arrester. By adding the overvoltage suppression circuit, the overvoltage stress of the converter valve equipment under the in-station extreme fault working condition and in the alternating current system fault ride-through process is effectively reduced, the alternating current system fault ride-through capacity and the in-station extreme fault endurance capacity of the flexible direct current converter valve equipment are improved, and the large engineering application potential is achieved.

Description

technical field [0001] The invention relates to the technical field of electric equipment, in particular to a converter valve bridge arm sub-module with an overvoltage suppression function, a control method thereof, and a converter valve. Background technique [0002] The flexible DC transmission system based on MMC (Modular Multilevel Converter, modular multilevel converter) has flexible control and can realize independent decoupling control of active power and reactive power. Power supply, power grid black start, multi-terminal DC networking, weak system networking and other fields have great market application prospects. At present, there are several MMC topology application projects in China. [0003] There are a large number of DC capacitor devices in the existing MMC-based topology. When the receiving end AC system fails or the converter station ground fault occurs, the system power will be surplus, and the surplus power will charge the module capacitors, resulting in...

AI Technical Summary

Problems solved by technology

[0003] There are a large number of DC capacitor devices in the existing MMC-based topology. When the receiving end AC system fails or the converter station ground fault occurs, the system power will be surplus, and the surplus power will charge the module capacitors, resulting in system overvoltage. , seriously endangering the safety of primary equipment

At present, the solution to system power surplus is mainly by installing energy-consuming devices on the AC side or DC side of the system. In the case of AC system faults, putting in energy-consuming devices to consume surplus power can realize fault ride-through of the AC system, but the investment in the entire equipment is relatively high. Large, especially the AC energy consumption device cannot solve the problem of freewheeling overvoltage caused by faults in the receiving station

For the overall freewheeling overvoltage of the sub-module of the single bridge arm of the converter valve caused by the ground fault in the station, the overvoltage limit can also be limited by connecting lightning arresters at both ends of the bridge arm in parallel. However, this method is a passive defense and cannot control the lightning arrester. It also cannot solve the overvoltage problem of the converter valve caused by the failure of the AC system

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