Experimental and simulation studies on lightning surge responses of a scaled-DC converter station

Abstract:
HVDC projects are widely used in China because of their large transmission capacity and long transmission distance, and more new projects are under construction. Operational experience has shown that the transient process of converter stations caused by lightning strikes is one of the main threats to the safe operation of HVDC projects. Therefore, accurately analysing the lightning transient response of converter stations and proposing targeted protection schemes are the main means to deal with this threat. As a favourable candidate for analysing the lightning transient response of converter stations with complex structures, the FDTD method has been widely used in the transient analysis of transmission lines and substations. These analyses are mostly based on self-developed FDTD codes, which need to be validated by scaled or actual experiments for their use because of the lack of commercially available dedicated software. Similarly, when applying the FDTD method to the lightning surge response analysis of an actual converter station, it is also necessary to verify the self-developed code. However, no reported experimental results exist for lightning surge responses in converter stations, either scaled or actual. To address this, this paper presents a scaled experimental platform for the surge response of a converter station's DC switching field and incoming transmission line. We obtain experimental results for the surge response of the scaled converter station. Concurrently, we establish a computational model of the surge response of the scaled converter station using the FDTD method. The simulation results align with the experimental results, validating that the FDTD model established in this paper can be applied to the analysis of the lightning surge response of converter stations.