In the non-characteristic harmonic load flow algorithm for high voltage direct current(HVDC) system,the nonlinear equations are charactered by the multivariable and huge dimension.Newton-Raphson iterative method is applied to improve the convergence of the non-characteristic harmonic load flow algorithm.The analytic expressions of three phases AC current,DC voltage,and circulation current at Δ side in Y,d transformer are deduced.According to the relationship between the AC-DC network and converter device,ba...