Current Regulator Generalized Design of Grid-Connected Converter with LCL Filter

In practical applications, the setting of control parameters of grid-connected converters is affected by various factors such as system power rating, filter parameters and sampling frequency. The parameters of PI controller in industry applications are often determined by trial and error method in a certain range, which is different from system to system. In addition, the selection range of controller parameters is large, making it difficult to distinguish system stability by trial and error method. To address these issues, a current regulator generalized design of grid-connected converter with LCL filter is presented in this paper. First, the filter parameters are derived as a function of four system parameters: power rating, DC side voltage, grid voltage and sampling frequency. Afterwards, the generalized transfer function and regulator parameter setting of different systems could be obtained. In order to improve the applicability even if the filter parameters are not designed according to the given rules ˈ the correction coefficients are introduced. It could be deduced that the proportional parameter can be designed by given cut-off frequency and system parameters, and integral parameter are related to the cut off frequency and proportional parameters. Finally, simulation and experimental results indicate that the generalized PI parameter design proposed in this paper has good performance and wide application range.