Research On Harmonic Detection Transmitter

With the industrial development and technology advanced, non-linear power electronic devices usage rate increases in the power system, which brings about more and more harmonic pollution in the power grid, makes the power quality level dropping and causes all kinds of the electrical equipment fault. And the harmonics will be a threat to the security, stability and economical operation of power system. The harmonic problem becomes an urgent problem, and the harmonic detection providing basis support for the harmonic problem is of great importance.Taking the definition, source and harms of the harmonic as research background, and base on the fundamental theory analysis of Fourier Transform and Wavelet Transform, This dissertation through analyzing different methods of the harmonic detection, and compared their advantages and drawbacks with each other. Moreover expound the Fast Fourier Transform(FFT), Wavelet Transform(WT) and Wavelet-package Transform application in harmonic detection.The simulation by Matlab for different signal to be different detection of harmonic ways measured. The simulation results that applying the Fast Fourier Transform in the harmonic detection can cause spectrum leakage and fence effect, which in order to refrain the measurement errors, this paper use an algorithm based on Blackman-Harris’ s window and the triple-line interpolation FFT, which can increase the accuracy of results of harmonic detection. In addition for the detection of non-stationary signals can use Wavelet-package Transform, and it has more advantages than FFT.The hardware of transmitter choose TMS320F28335 as the core controller, that mainly using transform circuit of signal, condition circuit of signal, collection circuit of signal and communication interface circuit to complete the hardware design; on the basis of the hardware design, the software of the transmitter includes data acquisition, data processing and communication module. The data processing module includes calculation of window interpolation FFT and Wavelet-package Transform algorithm. The experimental results show that the harmonic detection transmitter can be able to achieve harmonic detection and analysis of three-phase voltage and current signals, and through connection with the communication interface, this design, brings convenience to the on-site monitoring and remote monitoring.