Predictive analysis for radiated electromagnetic disturbance in MMC-HVDC valve hall

The radiated electromagnetic interference (EMI) in the valve hall of the modular multilevel converter (MMC) station must be limited below a certain value to ensure the normal operation of the equipment and the safety of the engineers. In this paper, a method for predicting the radiated EMI is proposed, which takes all the necessary factors, such as the physics-based characteristics for IGBT module, sub-module topology, and converter space structure into consideration. This method involves the improved physical model of semiconductor devices, which discards the non-physical feedback parameter introduced by some previous research. At the same time, through the decoupling of the submodule and the bridge arm circuit, the order of the large-scale system is reduced so that the sub-modules can be calculated in parallel, greatly reducing the overall calculation burden of the model and accelerating the nonlinear small time-step simulation. The wideband characteristics of the converter valve tower are fully considered, with each of the bridge arms regarded as a two-port network with independent sources. The parameter integration and distribution process can also achieve complete parallel calculation. The converter valve tower is modeled as a complex antenna structure with the output voltage of each sub-module as the excitation, the calculation of near-field radiation intensity for the converter valve tower is performed in Alteir̅ FEKO. The measurement conducted inside an actual 49-level converter station verifies the accuracy of the model.