Lifting wavelet transform and energy operator synchronization for a flying capacitor multi-level inverter based active power filter

An online harmonic estimation technique is proposed based on lifting wavelet transforms. The effectiveness of this technique is successfully verified in the paper through analyzing the current samples supplied to a practical building network which are unbalanced and corrupted with noise. Combining with a novel synchronization technique based on the energy operator principle, this scheme is applied to control a flying capacitor multilevel inverter based active power filter shunt connected to a power network. Simulation study has shown that the performance of this filtering technique is superior than the conventional synchronous reference frame based harmonic elimination method.