Comparison of Suitable Control Systems for HVDC Stations Connected to Weak AC Systems Part I: New COntrol Systems

During unbalanced conditions the dynamic performance of HVDC transmission systems connected to weak ac systems depends strongly upon the control systems of the dc link. Different new grid control systems and closed-loop control methods have been developed. The principles of these new control systems are described in Part I of this paper. Part II deals with the results obtained with these methods during steady-state and dynamic operation under balanced and unbalanced conditions as well as with the harmonic content in the associated ac networks.