Design And Implementation Of Power System Harmonic Analyzer Using FFT Technique

That grid harmonic is power pollution is accepted internationally, we must take measures to limit harmonic level. The first problem is to detect the harmonics. Harmonic measurement is taken either power quality analyzer or the harmonic analyzer. At present, the domestic market is occupied by foreign testing instruments, such as, American FLUKE, Japan HIOKI and so on. The foreign products are excellent performance, full functions, but expensive. The price of domestic product is moderate, but the accuracy is poor generally. Currently, the use of digital signal processor platform is a mainstream technology, the Fast Fourier Transform (FFT) is one of the most widely used measurement method.This thesis discusses the design and implementation of a grid harmonic analyzer. The overall design is based on the standard GB/T 2008-11626.7<Electromagnetic compatibility -Testing and measurement techniques-General guide on harmonics and interharmonics measurement and instrumentation, for power supply systems and equipment connected thereto> (IEC 61000-4-7:2002, IDT). Discussing the factors influencing the analysis precision in detail, the author proposed hardware and software solutions. The author intends to use the Texas Instruments (TI) digital signal processor TMS320F28335 as core Processor on hardware platform, Hardware resources include: three-phase voltage/current signal acquisition, ADC AD7606, LCD screen, keypad, serial communications. The applacation software is compiled by the majority of C language, combined with assemble language based on an integrated development environment Code Composer Studio v4 (CCS V4.0). Harmonic measurement method: a floating-point type, improved FFT algorithm (fast harmonic analysis time<5mS), ADC sampling rate:12.8kSPS (256 points/cycle). Conclusion:harmonic measurement precision rank:A class. Its main function includes the analysis of harmonic components, characteristic harmonic component alarm and the electrical parameters of power system including voltages, currents, power frequency, active power, reactive power, power factor are monitored in real-time precisely.The result of this paper is a portable grid harmonic analyzer. It is low cost, high precision, which can be applied to the actual scene, it has good market prospects. At present, the design scheme of TMSF2812 (fixed point DSP) is more, and the new model of TMS320F28335 is less, which can provide a reference for future designs. In addition, the design scheme is also a reference of active power filter’s harmonic measurement.