Sub-module fault diagnosis method of modular multilevel converter

Abstract

The invention discloses a sub-module fault diagnosis method of a modular multilevel converter in the technical field of power transmission and distribution. According to the technical scheme, the method includes: firstly, performing fault feature analysis aiming at typical faults of sub-modules; secondly, configuring an SFDU (sub-module fault diagnosis unit) in an SMC (sub-module controller), and combining provided sub-module fault diagnosis indexes by the aid of capacitor voltage, bridge arm current and trigger signals at the moment so as to achieve diagnosis of faults of sub-module IGBT (insulated gate bipolar translator) short circuit, IGBT open circuit, FWD (freewheel diode) short circuit, capacitor failure and the like; and finally, adopting an exclusive method in a VBC (valve base controller) to achieve diagnosis of faults of sub-module FWD open circuit, capacitor open circuit failure, connection line open circuit and the like. The method has the advantages that diagnosis of sub-module faults is achieved on the base of software, additional measuring points are not added to an original control protection system, and the method is easy to implement, has quick and efficient sub-module fault diagnosis capability, and has coordination with other protection settings.

Description

Technical field [0001] The invention belongs to the technical field of power transmission and distribution, and in particular relates to a sub-module fault diagnosis method of a modular multilevel converter. Background technique [0002] Modular Multilevel Converter (MMC) is a new voltage source converter topology proposed by R. Marquardt and A. Lesnicar in 2002. It does not require a large number of IGBTs in series, and the device withstands voltage change rate is low. The output waveform has lower harmonic content and other advantages. Therefore, the MMC-based high-voltage direct current transmission system (MMC-HVDC) is also a research hotspot in the field of direct current transmission in recent years. [0003] At present, the sub-module (SM) widely used in the project adopts a half-bridge type sub-module structure, which is the basic unit that constitutes the MMC. The timely diagnosis and in-situ protection of fault conditions during operation directly affect the stable opera...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problems mentioned in the background art that the hardware circuit design of the drive protection circuit on the sub-module controller SMC is complicated and some types of faults cannot be diagnosed and the diagnosis ability is poor, the present invention proposes a modular multi-level commutation Fault Diagnosis Method for Sub-modules of Devices

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