Power-synchronization loop for vector current control of VSC-HVDC connected to weak system

Effective control of VSC-HVDC connected to weak system is one of the important issues related to the reliable operation of the entire DC system. Firstly, the operation principles of the traditional Vector Current Control are described, and the mechanism of its failure in control due to PLL can't get phase-locked accurately in the transient process when connected to weak system. Then an integrated method combining Power-Synchronization Loop and Vector Current Control is proposed as the control method for VSC that connected to weak system. At last, a VSC-MTDC model with three terminals (one terminal connected to weak system) established base on PSCAD/EMTDC is used to demonstrate the better transient performance of proposed method compared to the traditional Vector Current Control.