Fuzzy LogicController based MultilevelSTATCOM for High Power Application

Abstract

In this paper, in order to obtain VAR compensation multi-level inverter topology which is based on cascaded two level inverter is proposed. Through the open end windings of three phase transformer standard two level inverters are connected in cascade. In order to obtain four level operation the DC link voltages of the inverters are regulated.   A  good  number  of  multilevel  inverter topologies  have  been  proposed  during  the  last  two  decades.  Although different  multilevel  inverter  exists,  Cascade  Multilevel  Inverter  (CMI)  is  one  of  the productive topology  from  multilevel  family. In reality, on comparing with other multilevel based topologies, CMI feature a high modularity degree because each inverter can be seen as a module with similar circuit topology, control structure, and modulation. Static var compensation by cascading conventional multilevel/two level inverters is an attractive solution for high-power applications. The topology consists of standard multilevel/two level inverters connected in cascade through open-end windings of a three-phase transformer. One of the advantages of this topology is that by maintaining asymmetric voltages at the dc links of the inverters, the number of levels in the output voltage waveform can be increased. This improves Power quality of the system. Therefore, overall control is simple compared to conventional multilevel inverters.The proposed concept can be applied to fuzzy controlled system for better performance by using Matlab/Simulation software.