Analysis of HVDC converters connected to weak AC systems

A method of analysis is presented and applied to a model system which is well established and extensively used in studies of HVDC converters connected to weak AC systems. The method is based on fundamental frequency quantities. A variety of phenomena and interactions of the AC/DC system can be analyzed, and basic understanding of the mechanisms can be gained. Some important properties of the system, such as voltage/power stability in different control modes and stability of tap changer action, are analyzed. Furthermore, they dynamics of a system consisting of a static VAr compensator (SVC) and DC converters are analyzed, and the requirements for stable operation are derived within the framework of the method of analysis presented. These results are verified by time simulation done by a transient stability program.<
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