Study On The Distributed Control System Of Modular Multilevel Converter

With the rapid development of power electronic technology, multilevel converter is becoming one of the hottest spots in the field of high voltage and high power application. Modular multilevel converter(MMC)is the most outstanding one with the feature such as modular structure, easy to manufacture, easy to expend and maintenance. All these advantages make it rapidly becoming the most popular technology in high voltage and high power field for both research and application. So this paper will concentrate on the control system of MMC, and study some key technologies of its control system.This paper begins with the introduction of two key technology used in MMC. The first one is power electronic building block(PEBB), which is the core technology for the modular of MMC. Form the study of PEBB, this paper conclude some guidance for the design of MMC’s control system. The second one is distributed control technology, which is the core technology for the control of MMC. But, for some reasons, the present distributed control systems for plant are not suitable to MMC. So we studied where the problems lie, and how to solve them in the following chapters.First, this paper introduce two different methods to evaluate the performance of the control system, and studied how the performance is influenced. By using the PEBB technology, this paper put forward a hierarchical method in both hardware and software for the control system, which is very helpful in system’s design stage.Then, this paper introduced three basic topologies and analysis their advantages and disadvantages in detail. By studying how these topologies affect the control system’s performance, we summarize some methods on how to design topology for a system. After that, this paper studied the communication protocols, which have very tight connection with topology. Because different topologies need different communication protocols to coordinate. By analyzing the synchronous performance of different communication protocols, this paper studied how they can be used in the distributed control system and what problems will they meet. Particularly, this paper studied the synchronous problem of the circle topology’s communication protocols and what technologies are used to get the problem solved.Based on the research we have done, this paper developed a high speed serial optical communication protocol, which is suitable for the star topology, then finished the relative programming and simulation on Quartus13, and verified its reliability on a hardware prototype. In the end, we developed a set of distributed control system. After considering many factors which may came across in industry application, this paper used many reliable technologies to ensure that the control system has very high practical value.