Construction Of Signal Model And Study Of Power Decomposition Measurement Algorithm Based On The Second Wavelet Transform

Nowadays, harmonic pollution in electric network has been serious day by day. Accurate recognition and decomposition of voltage, current and power signals is the precondition of the normally work in electric network, and also the foundation of deeply researching the power phenomenon such as electric energy flow, transform and consumption. Considering the good time and frequency feature of wavelet transform, the sub-band power measurement algorithm based on wavelet transform has been proposed in recent years. The algorithm can measure not only harmonic signal’s voltage RMS, current RMS and power on the whole band, but also the decomposed value on the sub band. But in the algorithm research there are still some problems that are not clear now and need to be solved, for instance, how to settle the low accuracy problem under un-periodic sample condition and its fast realization problem in the hardware. Actual application of the algorithm is being blocked by the reasons above.The sub-band power measurement algorithm based on wavelet transform was deeply researched and analyzed in this paper. The main content is below:(1) Considering the feature of unstable signal in electric network, voltage and current model which is adapt to power measurement was established. After that, it was validated the adaptability of the sub-band power measurement algorithm based on wavelet transform to unstable signal, and measured value was given in quantity.(2) The sub-band power measurement algorithm based on wavelet transform was deeply and wholly analyzed, and it was simplified by matrix form.(3) The sub-band power measurement algorithm based on lifting wavelet transform was deeply researched. It could effectively settle the problems, such as the complex realization and the low speed, which were brought by the first wavelet transform. At the same time, some problems were found:Lifting process could destroy the orthogonality of the wavelet filter banks. As a result, the algorithm accuracy was affected.(4) Sub-band wavelet power measurement algorithm based on adaptive convolve window was proposed for the first time. It could preferably settle the low accuracy problem of the traditional sub-band wavelet power measurement algorithm under un-periodic sample condition. To meet real-time measurement need, adaptive convolve window in its fast algorithm was constructed, and the coefficient was deduced.(5) Sub-band power measurement algorithm based on straight integer lifting wavelet transform was proposed for the first time. It had high accuracy and how speed, and was more suitable in the real-time realization of hardware.(6) The realization of sub-band power measurement algorithm based on straight integer lifting wavelet transform on DSP was finished for the first time. The DSP program could meet the real-time need, and had actual application value of hardware.(7) Existing problem and the further research direction of sub-based power measurement algorithm based on wavelet transform were discussed. The simulation results show that the analysis methods and the measurement algorithms are correct and effective.