A Digital Twin System of Capacitive DC Bank Using Rogowski Coil to Monitor Individual Capacitors

The reliability of dc link capacitors is closely related to the operational safety of the whole power electronic system. To meet the application requirements, it is usually necessary to use a series or parallel structure of multiple capacitors to increase the capacity and withstand voltage, which also makes it difficult to monitor the individual capacitors in the capacitor bank. This article proposed a digital twin system for dc-link capacitor banks with PCB integrated Rogowski coils as sensors. The system uses highly integrated Rogowski coils to obtain the operating currents of individual capacitors in order to realize parameter correction of the digital twin system and ensure that the digital twin system can accurately reflect the electrothermal behavior of the dc-link capacitor bank. In addition, the effect of operating temperature on capacitor parameters is also considered, and the capacitor parameters and the operating temperature monitored by the digital twin system simultaneously are used to standardize the parameters. The standardized parameters are used as indicators to realize the health status assessment of each capacitor in the capacitor bank, which further provide an important basis for operation and maintenance.