Research Ring Network Control Technology Of MMC-VSC-HVDC System

With the development and application of new energy sources, flexible HVDCsystem has been rapid development, which has many advantages in transmission mode,to solve the many problems that exist in the conventional transmission, so it will bringnew energy distributed generation systems a huge impact, but also lay a goodfoundation for the development of smart grid. Control MMC-VSC-HVDC system isone of the key issues of the flexible HVDC study advanced control strategies andhigh-speed controller imminent. MMC converter and controller between the presenceof large number of parallel fiber optic control lines, plus MMC is currently no uniformstandard, control lines are too complex and the cost is too high, it carried out atechnical study of the new MMC-based control PEBB converter, while developed inline with technical standards PEBB MMC module, called MPB module. For themodule design MPB from theoretical research, simulation and design have made avery rigorous theoretical ideas and design, research achievements mainly by thefollowing aspects:First, the proposed converter control system architecture based on MMC PEBB,referred to MMC-PEBB framework. PEBB is based on the high-speed fiber as a carrier,MMC, SM, as each node to form a serial ring network control technology. This controltechnology to meet the requirements of speed control and synchronization, is able tosimplify the control structure, save a lot of expensive high-speed optical fiber, greatlyreducing the cost of VSC-HVDC system. In this framework, based on the studyconducted a double-loop topology of the network, to improve the reliability of thecontrol system; PEBB also given a ring network based communication protocol(MMC_PEBBNet), improved the overall MMC_PEBB control system architecture.Secondly, a new MMC control algorithm that hysteresis window DPWMtechnology. Hysteretic window technology allows the PWM duty cycle of50%, reaching the optimal control, increasing the IGBT turn-on time, reducing theswitching losses of the IGBT. While the application of the hysteresis window to sortequalizing control algorithm, the switching frequency of the IGBT is reduced, i.e.reducing the operating frequency of the IGBT, once again reducing the loss of theIGBT, the new control algorithm simulation and FPGAoperation was a success.Finally, developed a network to meet PEBB FPGA controller, in order to achievereal-time control, you must choose to design a high-speed optical networks, the use ofSFP optical module communication has become inevitable, the use of low-poweroptical modules, hot-swap capability, anti-interference ability and speed, etc.,developed FPGAas the core controller with4-channel optical networks.