Digital harmonic acquisition with delay time compensation based on the improved d-q transformation

Harmonic detecting plays an important role in active power filter for the line harmonic suppression, and DSP is increasingly used for digital harmonic detecting method, but there is a delay time from load current sampling to harmonic compensation using digital harmonic detecting way. In this paper, a new algorithm based on the improved d-q rotating coordination transformation is presented, which add the delay time compensation angle ΔΘ into the C^I of conventional d-q rotating coordination transformation, the theory analysis and the experimental results proved that the algorithm can compensate the influence of the conventional digital way´s delay time on the harmonic compensation and realize the real time compensation.