Analysis and suppression of the aliasing in real-time sampling for grid-connected LCL-filtered inverters

Real-time sampling and feedback can effectively reduce the sampling delay and improve the robustness of the active damping control for grid-connected LCL-filtered inverter. However, the practicability of this approach would be limited by the aliasing problem of sampling. In order to solve the aliasing problem, a systematic analysis is done to figure out the relation between the sampling instant of digital signal processor (DSP) and the level of aliasing by establishing an aliasing analysis model based on the actual DSP working mode. Results show that the aliasing of traditional synchronous sampling method is lighter than that of the real-time sampling. Besides, combining with the demand of signal sampling for active damping, two methods including the multiple sampling and the real-time sampling with additional high-pass filter are presented to suppress the aliasing. Finally, simulation and experimental results show that the multiple sampling increases the difficulty of the software and hardware implementation, and real-time sampling with additional high-pass filter is simple and practical.