Observations about Propagation, Attenuation, and Radiation of EMI from HVDC Converter Stations

The electromagnetic interference (EMI) generated by switching operations within high-voltage DC (HVDC) converter stations is an issue that has been addressed by CIGRE, and methods to manage EMI should be considered in the design phase using electromagnetic modeling techniques. It is shown that the methods of the moments-based techniques that have been used in many previous studies may not be sufficient. Here, a finite-difference time-domain method is used to study the properties of single switching events using a realistic model of an HVDC converter station with a special emphasis on determining the impact of the valve hall on shielding EMI. It is shown that the valve hall does not confine high-frequency electromagnetic fields to the valve hall; rather, it delays them from exiting through bushings in the wall and spreads them out in time. Further, it is shown that incorporating electromagnetic absorbing material into the valve hall’s design can significantly reduce EMI outside the converter station.