Based On The Research And Design Of Embedded Power Harmonic Detector

With the wide application of various electronic devices which are non-linear, the harmonics pollution in electric systems is much more serious. To prevent and manage, even charge for harmonics pollution, it is necessary to research into harmonics-monitor that is real-time, accurate and continuous-detected. The research is significant to theory and engineering.Most of present harmonics-monitors adopt the technique of Fast Fourier Transform (FFT) to detect harmonics. However, FFT needs longer time to collect and process the signal. Further more, there are grid-effect and frequency-leak in the processing, which leads to inferior real-time and precision. In addition, FFT is applicable to analyze gradually-changed signals instead of detecting harmonics when the load breaks.By analysis and comparison with present methods, this paper researches in depth into the self-adaptive detecting principle that is based on the artificial neural cell. Furthermore, a complete approach for harmonics detection is founded making use of self-adaptive noise countervailing technique and artificial neural network theory. The approach applies an artificial neural cell to realize the multi self-adaptive filter. As a result, it could accurately complete dynamic detection for odd, even, specific, or total harmonics. Besides the virtues of rapid response, high precision and outstanding self-adaptive ability, the approach is not affected by voltage distortion and frequency excursion.As the core of harmonics detection, the approach above is realized by digital signal processor (DSP) . Then the embeded surveymeter receives harmonics data via communication with DSP. deals with these data and calculates important parameter, including harmonic content, harmonic ratio, total harmonic distortion, fundamental active power, fundamental reactive power and so on. Thereby , a set of harmonics-monitor is developed. The system is integrated and intellectualized for its functions consist of harmonics detection, display, forecast and alarm.The designed harmonics-surveymeter may be applied to single-phase circuit, balanced or unbalanced three-phase system. It provides an effective and utility method for continuous and real-time harmonics monitor.