Research on fault diagnosis and online monitoring method of M3C submodules

Abstract

There are a large number of submodules in modular multilevel matrix converter （M3C）. Conventional fault detection and location methods have problems such as low efficiency， insufficient coverage and poor equivalence. It is particularly important for the stable operation of the M3C converter station to realize batch non-intrusive fault detection of the submodules and the online state monitoring of its capacitor. Therefore， this paper designs a strategy of non-intrusive fault detection and location for submodule IGBT based on low-voltage AC source pre-charging method. Moreover， it puts forward an integrated online monitoring method of state parameters of submodule capacitors based on submodule capacitor voltage jump characteristics and Kalman filter algorithm. Finally， the M3C converter station model is built in PSCAD/EMTDC simulation platform for verification. The simulation results show that the proposed method can efficiently and accurately realize fault detection， location， and online monitoring of capacitor state.

Keywords

• modular multilevel matrix converter
• submodule fault
• non-intrusive fault detection
• online monitoring of capacitor state