HVDC输电线路离子流场数值计算方法研究

为了解高压直流输电线路的电磁环境影响及电晕损耗,讨论了高压直流线路周围离子流场计算的数值方法。描述高压直流离子流场控制方程的三阶非线性偏微分方程分解为两个等效的泊松方程后可用有限元迭代方法求解即在每次求解后根据两场的计算结果更新空间电荷密度,反复迭代求解直至计算结果收敛。该算法舍弃了Kaptzov和Deutsch假设,并提出了一种有效的电荷密度更新公式,同时考虑两场电位差别、电场与边界条件的差别,使迭代较快收敛。通过与实验模型的测试结果对比,验证了算法的有效性。

Research on Numerical Calculation of Ionized Field Around HVDC Transmission Lines

Numerical calculation methods of ionized field around HVDC transmission lines have been discussed in this paper.An algorithm using finite element iterative solution is applied in the analysis of unipolar ionized field,the three-order,non-linear partial differential equation describing the ionized field is decomposed into two equivalent Poisson's equations which are easier to conduct with ordinary finite element technique.Under appropriate boundary condition involving electric potential of boundaries and electric field intensity on the surface of conductor where there is corona,the algorithm starts with an guessed initial charge density throughout transmission line space,the guessed charge density will result in a difference between the results of electric potential of the fields corresponding to the two Poisson's equations.After solving these two equations respectively,space charge density can be updated according to the results of the electric potential and electric field intensity of the two fields.Both Kaptzov and Deutsch assumptions are waived in the method,an effective charge density updating formula which involves the difference between electric potential of two fields and the difference between calculated electric field intensity around conductor surface and the boundary condition is presented.The numerical results are compared with experimental results of tested HVDC transmission line model to verify the efficiency of the algorithm presented,both calculated electric field intensity and current density of ground level show reasonable agreement with experimental data.The present method is capable of calculating electric potential,electric field intensity and current density at arbitrary position in space,which are basic data for further assessment of engineer parameters such as U-I character and corona loss.