A Fast ion Flow Field Calculation Method of UHVDC Transmission Lines Based on Adaptive Iteration Factor and Half-Error Term

As an important indicator of the electromagnetic environment of UHVDC transmission lines, the ion flow field needs to be quickly calculated and updated in case to meet the requirement in building a digital twin of the power transmission system. This paper is based on the UFEM and starts from two aspects: electric field intensity convergence and charge density convergence. a) An adaptive iteration factor for charge density update is introduced, which can automatically control the iteration speed according to the change degree of electric field intensity, ensuring the rapid and stable update of charge density. b) On this basis, a half-error term is added to the charge density update formula. This controllable disturbance has little impact on the convergence of the charge density, but can greatly accelerate the convergence of the electric field intensity. Their combined effect greatly reduces the iteration steps required for the entire solution. A coaxial cylindrical model with analytical solutions and a real +/- 800 kV UHVDC transmission line project with test results are used to verify the method. In terms of accuracy, the numerical calculation results are exactly the same as the analytical solutions and are basically consistent with the test results. In terms of speed, compared with traditional fixed factors, after using the adaptive iteration factor, the iteration steps are reduced by up to 75%. In addition, after adding the half-error term, the iteration steps are further reduced by 32%. This method can strongly support the application of digital twin technology in power transmission.