Design Method For Harmonic Measurement Of Power System Based On DSP

With the wide application of various kinds of non-liner loads, the harmonic pollution is more and more serious. The quality of electric energy is badly influenced by the harmonics, which is also harmful to the power equipment operation. If the harmonic can not be controlled, it will affect the whole electric net running safe. The harmonic pollution control is inevitable.In order to detect accurate harmonic content of the power system, the most important problem to solve is harmonic detection and analysis. So according to electrical system requirement of real-time performance, high processing precision and huge amount of data to be processed, a system based on Digital Signal Processor (DSP), which is used to measure power parameters and harmonic, is proposed in this paper.Firstly, the theory of harmonic analysis algorithm is introduced in this paper. After the harm and origin of harmonics in electric power system are researched, some current methods using in harmonic analysis are compared. According to the method based on Fast Fourier Transform (FFT) in common used to deal with the harmonic measurement have the frequency spectrum leak and other problems. Some efforts have been made including the utilization of window functions and interpolation algorithms to correct the measured frequency, phase and amplitude by FFT. After theory analysis, the DSP processor chip TMS320LF2407A of TI Corp as hardware core, which is integrated 10 bit A/D converter to realize data acquisition, is used in system and detection hardware design in detail is given. This system is expanded with signal sensor, signal regulating circuit, data sampling circuit, communication module and human-machine interface. The software system is completed based on construction platform.The filter of FIR design, the algorithm of FFT, A/D calibration, and serial port communication are introduced in detail. The realization of other lower computer software module design and upper computer software are proposed.Finally, the experiment result has been proved that the harmonic detecting system has fulfilled the technical requirements of real-time character and accuracy, so the project has some practical value. Moreover, detailed error analysis of the experimental results is also given.