Research On UHVDC Control System Modeling Based On EMTDC

HVDC is playing an increasingly significant role in Chinese power construction, for its evident characteristics that it is suitable for the remote distrbution of electric power and that it is convenient for the interconnection of AC system among different regions. Two±800kV ultrahigh-voltage direct current (UHVDC) projects, one between Yunnan and Guangdong, the other between Xiangjiaba and Shanghai, have been put into operation in the last June and July respectively, which indicates a brand new start for the DC transmission technology.Easy-controlling with fast speed is one of the most remarkable advantages for HVDC. The control system plays a key role in the HVDC system and in a way, it determines the operation of the whole HVDC system. Analyzing structure and function of control system and studying the controlstrategy’s effects on the transient stability of AC system are indispensable to probe the operation stability of modern AC/DC network.UHVDC transmission systems use double12-pulse valve groups per pole as a main circuit designing structure which is different from HVDC. The core of the UHVDC transmission control system is summarized in this article by reasonable simplified the control system which has been put into practice. Modeling and simulation of±800kV UHVDC transmission system are carried out based on PSCAD/EMTDC, which can reflect the characteristics of UHVDC core control system, and then design experiments for simulation verification and analysis.