An overcurrent protection configuration method and system for a modular multilevel converter

Abstract

The present invention proposes an overcurrent protection configuration method and system for a modularized multilevel converter, in which the AC overcurrent protection of the converter and the overcurrent protection of the bridge arm are configured at the DC control and protection PCP layer, and the valve base of the converter is configured Control the VBC layer to configure the inverter bridge arm overcurrent protection, and configure the IGBT component overcurrent protection at the inverter sub-module layer; the protection setting and protection delay of the overcurrent protection of each protection layer are coordinated with each other through the inverse time limit protection method, Coordinate protection for the overcurrent of the converter valve group and converter sub-modules. The protection configuration method and system can quickly and correctly perform protection actions in the case of different faults such as AC system short circuit, DC pole short circuit, and converter valve short circuit, so as to prevent the overcurrent stress from continuing to develop, effectively protect the valve group body, and improve system reliability.

Description

technical field [0001] The invention belongs to the technical field of flexible power transmission in power systems, and in particular relates to an overcurrent protection configuration method and system for a modular multilevel converter. Background technique [0002] Flexible DC transmission uses voltage source converters, which can independently adjust the transmission of active and reactive power, improve the transmission capacity of the AC system, and easily form a multi-terminal DC transmission system. And other application fields, have obvious competitiveness. [0003] The valve arm of the modular multi-level converter (MMC) is composed of multiple sub-modules. The sine wave signal is output through the superposition of the output levels of multiple sub-modules. It has the advantages of reduced switching frequency, low loss, and small harmonics, and is easy to expand To a higher voltage level is the main direction of research and application of flexible power transmi...

AI Technical Summary

Problems solved by technology

[0005] The safe working area of ​​the IGBT device limits the fault current exceeding twice the rated value, and the device cannot be reliably turned off if it lasts for more than 10 μs.

Twice the fault current, lasting 1ms may cause device damage

A microsecond overvoltage pulse may cause complete damage to the IGBT

The above factors lead to the great limitation of the role of the DC control and protection system in the protection of the valve group body

Images