Research & Design Of Harmonic Restrain And VAR Compensation Device Based On DSP

In modern port electric power system, with the slather of the nonlinear element like power electronic device, the problems generated by harmonics and reactive power are becoming increasingly serious. Harmonics and reactive power not only deteriorate electric power quality, but also endanger system stability and safety, even generate accident of power system. Therefore more and more attention has been paid to harmonic restrain and reactive power compensation. Due to the limited operation ability of main controller, the traditional technology of compensation is difficult to analyze Real-time signal effectively and thus impacts the result of compensation. Since the birth of DSP in the early 1980s, with the unceasingly development in its function and research methods, DSP has earned its widely uses in the fields of communications, signal and information processing as well as the automation control. It now can fully meet the requirements of signal processing in power system.Contraposing the development status of harmonic restrain and reactive power compensation installation in port electric power system, through the analysis of the theory of harmonics and reactive power and combining with the research both in domestic and overseas, several popular methods are compared. In the light of the practicability and economic efficiency principle, we proposed a second derivative damping filtering and power compensation device which based on TMS320LF2407A chip made by TI(Texas Instruments) as the main controller. This installation can be used to monitor and control harmonics and reactive power in power network.To enable the effective monitoring of networks, this installation utilizes the MAX293 chip for anti mixed signals recovery processing of secondary winding in transformer, and uses MAX 125 chip, CD4046 chip to complete the work of phase lock and synchronous sampling. Use DSP chip to process voltage and current sampling signal with FFT, and obtain Vrms, I_rms of three-phase, harmonic no more than 32nd and power factor, comparing measurement signal with predeterminedswitch conditions, trigger thyristor circuit instantly. It can realize compensator's speediness, no arc, no concussion switching, so that to achieve the aim of harmonic restrain and reactive power compensation. On the basis of theoretical studies, we use MATLAB software to simulate the effect of compensator's switching and the experimental results show that the device could be effective in harmonic restrain and reactive power compensation. So it will be applicable to different kinds of low-voltage distribution networks and plays its role of reducing line depletion and improving the quality and stability of the power grid operation.