Integrated Power Harmonic Intelligent Monitoring System

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 computer receives harmonics data via communication with DSP. LabVIEW-Laboratory Virtual Instrument Engineering Workbench -deals with these data and calculates important parameter, including harmonic content, harmonic ratio, total harmonic distortion, fundamental active power, fundamental reactive power and soon. Thereby, a set of harmonics-monitor is developed. The system is integrated and intellectualized for its functions consist of harmonics detection, display, forecast, alarm and protection.The designed harmonics-monitor 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.