| Summary: | 碩士 === 國立中正大學 === 電機工程研究所 === 92 === With the widespread use of nonlinear loads in the power system, harmonic distortion nowadays causes a serious pollution of power quality. Besides, there are slight variations in the system frequency caused by the dynamic change of the balance between load demand and the power generation. These disturbances may introduce operational problems of power system equipments. Therefore, power quality problems have become a great concern for both utilities and customers.
The Fast Fourier Transform (FFT) has been widely used for the signal processing because of its computational efficiency. In addition, most power meters adopt FFT-based algorithm to analyze the harmonics and to show the frequency spectra. However, the FFT-based algorithm is less accurate if the system frequency varies and the frequency resolution decreases, the analytic results will show errors caused by the leakage and picket-fence effects. Therefore, how to achieve the good accuracies for measuring signals in real-time is worth investigating.
According to aforementioned facts, this thesis proposes an FFT-based improved algorithm for harmonic and interharmonic measurement. Not only the calculation time is reduced, but also the result is with a better accuracy, even if the power signals contain frequency variations and non-integer harmonic components. Finally, the thesis applies LabVIEW and the dedicated hardware to design a simple setup for measuring power quality signals, and the performance of improved algorithm is validated by testing the synthesized and actual signals.
|
|---|
