Accelerated UMEC Algorithm of the 500kV 4-limb Converter Transformer Model for PSCAD/EMTDC

To precisely model the transient behavior of the 4-limb converter transformers used in the Kunliulong VSC-LCC HVDC project during faults or breakers operations, it is required to rewrite a new 4-limb transformer model instead of the built-in 2-limb single-phase UMEC model for use in PSCAD/EMTDC. The modified UMEC model takes the structure and the magnetic paths of the 4-limb iron core into account. Considering that the UMEC and converter model requires a heavy computation load, improving the UMEC algorithm to meet the HVDC simulation requirements is suggested. The model is verified by the factory experiment datasheet and field experiment data of both the 158V 4-limb prototype and 303kV transformer. The model is finally integrated into the Kunliulong HVDC PSCAD model and the results show that the model can precisely model the transient behavior of the power system.