Abstract
In order to adapt to a low-carbon economy and social development needs, and to solve the energy and resource requirements in the reverse distribution, ultra-high voltage alternating Current and direct current transmission are developing in our country. At present, the mainstream of the high-voltage direct current transmission topology is modular multilevel inverter direct current transmission (MMC-HVDC). It will be get more application in ultra-high direct current transmission in the future. In this project, the main points in the study of MMC-HVDC are as follows. This project derives the basic operation principle of MMC and the mathematical model of the ABC three-phase MMC, and uses dq and αβ coordinate transformations to get equivalent mathematical model in dq and αβ coordinates. Further, in this project, PR controller concept is introduced which can implement AC for communication astatic tracking. It uses MMC system double closed loop internal control and the realization of active and reactive power decoupling control, on the basis of implementing the MMC output current of the reference signal of difference and rapid tracking. This can achieve better control performance. The project presents the PR controller design principle and control block diagram, and design of some key parameters. Finally, the simulations verify that the designed controller implements the good running characteristics of MMC-HVDC system.