On the Stabilization and Stability Domain Estimation of VSC-HVDC Transmission Systems

Control of Voltage Source Converters (VSC)-based HVDC (High Voltage Direct Current) transmission systems is developed in this paper. The proposed approach aims at stabilizing the power VSC, which is characterized by nonlinearities due to requirements of power flow and DC bus voltage. The steady-state average model for the VSC-HVDC system is developed on linear and bilinear deviation state-space models around the working point. Based on poles placement and Least Squares (LS) methods, linear and nonlinear polynomial feedbacks are considered. The proposed approach leads to regulate simultaneously the dq grid currents and the DC bus voltage. By upon the time domain simulations in MATLAB/SIMULINK/SPS environment, the effectiveness of the proposed control strategies is tested on a VSC and a point-to-point VSC-HVDC transmission system. The simulation results show the robustness of the studied systems under various conditions.