Power flow calculation of power systems incorporating VSC-HVDC

Voltage source converter (VSC) based HVDC (VSC-HVDC) technology is a kind of newly developed HVDC transmission technology. This paper makes detailed analysis to the basic principle and the structure of VSC-HVDC, and sets up the steady-state mathematical model of VSC-HVDC, under fixed control parameters and fixed power flow control objectives respectively. Then a novel algorithm for power flow calculation based on equivalent injection power is deduced. A power flow calculation program of power systems, incorporating VSC-HVDC transmission lines and multiterminal VSC-HVDC networks, is developed based on the user programming interface (UPI) of power system analysis software package, PSASP/UPI. Numerical examples of EPRI 7-bus test system with a 2-terminal VSC-HVDC line and a test system with 3-terminal VSC-HVDC network are given. The results show that the proposed steady-state model of VSC-HVDC and corresponding power flow calculation based on PSASP is correct and effective. This software package provides a powerful tool for planning, design, operation, management, and relative control strategy studies of VSC-HVDC systems.