Condition Monitoring of Submodule Capacitors in Modular Multilevel Converter Using Digital Twin

Abstract

Modular multilevel converter is a fast emerging critical technology in HVDC applications. It comprises of high number of capacitors and reliability of the converter highly depends on the capacitors. Condition monitoring of these capacitors have become necessary to ensure the reliable and efficient operation of the modular multilevel converter system. In this paper, a digital twin concept based condition monitoring method of submodule capacitors of modular multilevel converter is proposed. The proposed method does not require any additional hardware cost and can be simply implemented via software. Furthermore, it monitors the capacitor status of all the submodules at the same time without affecting its operation. The efficacy of the proposed algorithm has been verified with different levels of degradation in the submodule capacitor. Further, the same algorithm is implemented on the three phase modular multilevel converter. The results concluded that the digital twin-based condition monitoring technique could estimate the degradation of the submodule capacitor with high accuracy without additional hardware.