Analytical method for computing steady-state response of HVDC

An analytical method for steady-state time-domain solution of traditional HVDC transmission system is proposed in the paper. The HVDC system is described as piecewise linear differential equations, the analytical expressions of steady-state time-domain solution can be obtained. By introducing auxiliary variables, the mathematic model can be written as a set of linear homogeneous differential equations, which can improve the computational efficiency. Contrasting with the method of numerical integration which is used generally now, the proposed method isn't limited by the integral step length and hasn't inevitable truncation errors, it doesn't need a long time boot process which must be need in EMTDC for steady-state solution. Beyond that the fundamental-frequency components and harmonics of converters in AC side can be obtained by using Fourier transformation. Using the proposed method to calculate the steady-state time-domain solution of a typical system, and compared it with PSCAD/EMTDC simulation results to verify the correctness and effectiveness of the analytical method.