Analysis on control and protection of MMC-based HVDC flexible transmission system

摘要

Combining with the first high voltage direct current (HVDC) flexible transmission system project in China, the demonstration project of flexible DC power transmission in Shanghai Nanhui Wind Power Station, this paper mainly introduces the modular multilevel converter (MMC)-based HVDC flexible system. This project that applies HVDC flexible transmission for the first time in China, has completed the experimental phase and been formally placed into operation. In this paper, the principle and the control methods of the system are studied; in addition, the startup methods and the control methods under normal conditions are introduced. Furthermore, the protection configurations and protection principles of the system are analyzed, which is of significance to the research on HVDC flexible system, as well as the operation and maintenance of the project in Nanhui wind power station.