With the development of power system technology, multi-terminal DC transmission based on voltage source converter has gradually become a superior choice for power transmission because of its decoupling control ability. Most studies about AC/DC power flow presented in the literatures use iterative method and nonlinear models. Work on linearization steady state model is still insufficient. An approximate linearized power flow model for VSC based AC/DC grid using logarithmic transform of voltage magnitudes (LTVM) is proposed in this paper. The model of AC/DC system and VSC are established. The logarithm of voltage magnitude is utilized as independent variables of power flow equations. This technique transforms the power flow equations of AC/DC grid from (V, θ, U) space to (v, θ, u) space, which makes power flow equations a set of linear equations. Simulation of the proposed method and classic iterative algorithm is performed in several test systems. The results demonstrate the validity and accuracy of the proposed method.
Keywords AC/DC Grid, Linearization, Power Flow, Voltage Source Converter