MMC Online Thermal Simulation and Life Prediction based on Digital Twin Technology

Abstract

Carbon neutrality is one of the most urgent global missions at the moment, many countries have shown true ambition for achieving this goal. The Chinese government proposed to build a new power system mainly based on new energy with wind power and photovoltaics as principal sources of power supply, bringing new challenges to the reliability and power quality of the power system. The new power system requires the advancement of design, simulation, diagnosis and maintenance of extensive application of modular multilevel converters (MMC) as its extensive application in a wide range of voltages. The application-oriented and value-focused digital twin technology is capable of constructing digital twin models consisting of power electronic equipment with numerous components and complex structures, as well as characterizing all aspects of the whole life cycle of the equipment in models. This technique has been successfully applied in aerospace and other fields, but there is a paucity of literature on the development and application of MMC for digital twin technology. This paper develops the digital twin model for MMC electric-heat hybrid simulation based on the digital twin technology and applies the PLECS RTBox 2 simulator to operate the hardware-in-the-loop verification. This digital twin model can estimate the switching power loss in real-time and calculate the thermal behavior of the core power device IGBT. It realizes yielding the junction temperature of devices combined with the practical operation parameters and environmental data in real-time simulation. In turn, the digital twin model is applicable to monitor and manipulate the health status of devices, furthermore, the service life of the MMC can be assessed to develop a reasonable maintenance plan.