Strategy for grid low-frequency oscillation suppression via VSC-HVDC linked wind farms

Abstract

The effective suppression of low-frequency grid oscillations by the offshore wind power in a voltage source converter-based HVDC (VSC-HVDC) output system can enhance the operational stability of the overall power system. In most existing studies, low-frequency oscillations are suppressed by controlling active power. However, active regulation can reduce the utilization of new energy sources. Therefore, this report proposes a reactive power suppression strategy based on frequency feedback. First, a mathematical model of the VSC-HVDC system is established to derive the mechanism of reactive power suppression of low-frequency oscillations in the receiving-end converter. Second, DC voltage control and AC-side reactive power control are adopted in the sending-end converter of the VSC-HVDC system, and DC control and AC voltage control are adopted in the receiver station. Finally, the single infinity system is subjected to a simulation analysis using MATLAB/Simulink. The simulation results demonstrate that this strategy can effectively suppress low-frequency oscillations of the grid, while simultaneously reducing the investment cost of reactive power equipment and improving the wind turbine utilization efficiency.