Improved continuation power flow method for AC/DC power system

An improved continuation power flow method for the AC/DC system is proposed in this paper. The three level control strategies and the coordination of the control modes for DC systems are presented. Firstly, the load-type continuation power flow is introduced in brief. Secondly, the concept of the three-level control and their coordination are proposed. The reactive power control strategy is classified into two categories: 1) Reactive Power under Control and 2) Voltage Magnitude under Control. If the control angle is out of its range, the converter transformer tap should be changed to restore the angle. The voltage or reactive power demand is achieved by coordinating the three level control strategies. Finally, the details of the proposed method are proposed. Numerical simulations show that the approach presented in this paper has advantages in terms of convergence and speed.