The accurate calculation of loss and junction temperature of modular multilevel converter (MMC) is an important basis for device selection, life prediction and reliability analysis of flexible DC transmission system. These instructions give you basic guidelines for preparing papers for conference proceedings. Currently, the commonly used loss and junction temperature calculation uses the fixed junction temperature method, which has some errors with the actual situation. An MMC power device loss and junction temperature calculation method considering the junction temperature feedback method is proposed in this paper. The power device loss distribution is analyzed from the operating mode of the half-bridge sub-module, and then the junction temperature feedback calculation method is introduced in detail on the basis of the fixed junction temperature loss calculation method. The loss and junction temperature calculation relative errors of fixed junction temperature method and junction temperature feedback method are analyzed by using the actual converter station MMC system as the calculation example. The distribution characteristics of loss and junction temperature in MMC submodules under different operating conditions are also analyzed. The proposed method can be used as a reference for the loss evaluation of high-voltage and large-capacity flexible DC transmission systems.

Modular multilevel converter,Loss,Junction Temperature,Feedback