Dynamic performance analysis of control systems for a DC transmission system including wind turbine generating systems

A DC transmission system including wind turbine generating systems has been proposed and its steady-state performances have been revealed. The proposed system can be used as an offshore wind farm. In this system, each voltage on the DC transmission line should be controlled properly for utilizing wind power to the maximum. In this paper, the control systems are developed first, and their dynamic performances are discussed. It is shown that the dynamic responses of the system become oscillatory. These oscillations can be diminished by applying current minor loops to the control system. Furthermore, two types of the maximum power tracking control systems for the wind turbine generating systems are compared. It is clarified that the turbine torque control is appropriate for the proposed wind turbine generating systems. Finally, a method of improving the maximum power tracking control system is suggested and its dynamic responses are analyzed.