Study On Control Technology Of STATCOM Based On Hybrid MMC

STATCOM is also called SVG--static synchronous compensator, which is the main research direction in the field of reactive power compensation at home and abroad, and its role is mainly used to compensate reactive power, voltage adjustment and improve the s Tableility and reliability of power grid.The converter is the most important part of the STATCOM, this thesis deeply compares the common topology,and finally selected the MMC(modular multilevel converter) power topology, and analyse the mathematical model and control strategy of STATCOM.Firstly, the research on the capability of circulation inhibition and output level of the system has been the focus research of MMC-STATCOM. Therefore, this thesis presents a new topology structure, which is based on the traditional topology of MMC,add two H bridge module in each bridge arm,one can achieve fold increase the output level number. Another H bridge module can effectively suppress the circulation. And then this thesis analyses the structure and working principle of this topology in detail.Secondly, in order to realize the s Tablele output of the STATCOM system based on the new topology structure,this thesis studied the working principle and control strategy of the two H bridgein detail,for realizing the purpose of its suppression circulation and increasing the number of output levels.Again, analysis of the working mechanism of the new topology based on STATCOM, and introduces the detection method of instantaneous reactive current and the corresponding control strategy, the feed-forward decoupling control strategy and the CPS-SPWM based sub module capacitor voltage sequencing method are proposed. At the same time, the overall control strategy of the system is obtained.Finally,this thesis carried the simulation analysis, and analyse the control strategy of suppression circulation and increasing the number of output levels.According to the simulation of reactive power compensation and voltagebalance,The simulation results prove the correctness of the proposed scheme, And build the system hardware experiment platform, mainly introduces the important module of the hardware circuit and the software flow chart of each part, further verifies the feasibility of this thesis in the practical application.