Research on methods of harmonic detection based on second generation wavelet algorithm

In the power system, it is necessary to real-time detect amplitude and phase of harmonic current in order to compensate for harmonic current. Therefore it is the key of seeking an algorithm by which harmonic current can be quickly and accurately detected in the process of active power filter (APF) compensating for harmonic current. The second generation wavelet algorithm (also called lifting algorithm) is a new construction method that first generation wavelet algorithm is decomposed into finite steps, and the wavelet transform at time or spatial domain can be directly completed through lifting wavelet algorithm. The calculation can be done in-place. In this paper lifting scheme of daubechies 9/7 wavelet filter is applied in the harmonic detection, the analysis of frequency-domain characteristic of harmonic signal is realized, computational complexity is greatly decreased, the running time can be effectively reduced. The second generation wavelet algorithm is used for harmonic signal process by analyzing the basic principle of second generation wavelet algorithm, and the simulation result is compared with the result of first generation wavelet algorithm and the result is satisfactory.