AC/DC Power Flow Algorithm Considering Various Controls Transformation

In the power flow solution of AC/DC systems, the problem of how to describe the transformation of HVDC system control method effectively must be considered for operation and analysis of actual power system. In this paper, the conversion conditions of control modes of HVDC system are presented, especially the mutual conversion of control variables of rectifier side and inverter side, and the program for power flow are presented, which based on the method of equivalent power and principle of alternant decouple solving in AC/DC system. The control effect and mutual conversion of the main control modes in HVDC system are considered in this program. The DC circuit in the EPRI-36 was modified as an example for detailed calculation and analysis through the function of user program interface (UPI) of power system analysis software package (PSASP). The AC bus voltage of rectifier side and inverter side are regulated, and calculating the power flow for the corresponding operation state. The result shows that this algorithm can deal with transformation of operating mode caused by the change of operating conditions and are favorable to power flow calculation and simulation of large scale power systems.