An Analysis on the Influence of Input Filters to SVG systems and Corresponding Design Considerations

Previous publications regarding the design and specification of input filters for Static Var Generators (SVG) usually deals with the input filter only, and seldom pay attention to the influence of input filters to SVG systems performance. In this paper a detailed analysis on the input filter influence on SVG systems and corresponding design consideration are presented. Three types of input filters, i.e., L filter, LC filter, and LCL filter, are examined separately. Through frequency domain methods, such as transfer functions and Bode plots, the influence of each type of input filter to the SVG system stability and filtering characteristics is extensively investigated. As direct current- control taken as a major control strategy for SVG, all the different situations when adopting different current detection points are covered in the analysis. A comparison between LC filter and LCL filter is also presented with optimized filter parameters. Based on the analysis, the design considerations for different type of input filter under different current diction scheme are discussed, which lead to filter parameters different to traditional design. All the computer simulation and hardware experimental results verified the validity of the above analysis and design.