Two Newton-Based Improved Algorithms for AC/DC Hybrid Power Flow

The conventional Newton method faces plenty of challenges in calculating the power flow in AC/DC hybrid systems. This paper initially establishes a unified model for AC-DC systems to enable uniform iteration, mainly considering the multi-terminal DC based on VSC. Subsequently, an augmented rectangular coordinate model that incorporates converter losses is developed. In the rectangular coordinate system, the power flow equation is in quadratic form, and its Taylor expansion can be exactly expanded to the third term. Further, two improved algorithms, the retaining nonlinearity method and the optimal multiplier method, are proposed and implemented for the calculations. The computational results demonstrate their superior efficiency and precision.