Electromagnetic Coupling Simulation of Line Fault in HVDC Transmission System Based on PS CAD/EMTDC

In order to improve the reliability of line operation and reduce the line disoperation, the electromagnetic coupling between bipolar lines must be studied. Based on the actual parameters of a UHVDC transmission system, this paper establishes a HVDC transmission model by using PSCAD/EMTDC software and builds the DC link in the model into the same-tower electromagnetic coupling model. On this basis, this paper carried out the unipolar line fault simulation under different operation modes of HVDC transmission system, and compared with the line protection action criterion. The experimental results show that when the unipolar line breaks down, the fault line protection can operate reliably and the non-fault pole line cannot move, which proves that the line protection criterion is chosen to meet the engineering requirements. At the same time, the DC transmission system with step-down operation can reduce the inter-Electromagnetic coupling.