Self-adaptive resonance frequency tracking for digital notch-filter-based active damping in LCL-filter-based active power filters

摘要

In this paper, a self-adaptive resonance frequency tracking method is presented. The resonance frequency tracking is used in a LCL-filter-based active power filter to adapt the frequency of the notch filter applied for active resonance damping. By determining the resonance frequency of the LCL-filter and adapting the notch filter frequency, the bandwidth of the notch filter can be decreased, whereby the dynamic performance of the current control loop is increased. The notch filter frequency is adapted to the resonance frequency by a PI controller using the frequency depending difference in the attenuation of two band-pass filters which are kept equidistant below and above the notch filter frequency. At this, the symmetrical attenuation of both band-pass filters in the frequency range between them is used.