DC Voltage Control Strategy Research in Multi-Terminal HVDC System Based on Optimal AC/DC Power Flow

This paper is focused on an effective DC voltage control strategy of the VSC-MTOC system which is based on the optimal AC/OC power flow (OPF) procedure. In this system, a multi-objective OPF algorithm is executed at the first of the VSC-MTOC system to find the optimal reference values for the active power and the dc voltages of the voltage-regulating converters. The reference values are used to combine the generalized droop control then the generalized droop control characteristics are tuned depend on the result of the optimal AC/DC power flow. And then we can obtain the optimal choice of the control strategy in the VSC-MTOC system. In case of variation in load or generation of the grid, a new stable operating point will be achieved based on this method. This paper also considers the wind power to tune the control strategy. The results of the OPF algorithm and simulations performed on different cases of the VSC-MTDC systems, a five-terminal AC/OC system, are compared and analyzed, and demonstrate the efficient control strategy.