Study On Active Power Filter Of SVPWM Control Based On Indefinite Frequency Hysteresis

The development of modern science and technology brings convenience and benefits for people. But power quality is polluted seriously. Active power filter has become a main means to improve power quality and control the power grid harmonics as a kind of initiative compensation device.Researching of numerous literatures in detail, this dissertation elaborates the research purpose and meaning of active power filter. Through the analysis of deficiency of the load side current detection and traditional hysteresis control, the source current detection method combined with SVPWM control based on indefinite frequency hysteresis is applied in active power filter. The matrix transformation of traditional detection methods is complex, but the source current detection don't need calculate the harmonic current accurately through the complex harmonic calculations. So it is easier to be digitized and it is proved that the method is equivalent to the load side current detection. The traditional hysteresis control is fast and accurate, but the switching frequency of power devices is not stable. SVPWM has the advantages of high voltage utilization and optimal switching mode. However, its computation is very complex. Therefore, SVPWM is combined with the hysteresis control. The error current is controlled within the ring width through real time switching of SVPWM, which can make the system obtain high quality control and reduce effectively the switching frequency. Thus the system operation efficiency is improved.The theoretical derivation and mathematical calculation of the main system components are carried out. The system simulation model is established in PSCAD/EMTDC simulation platform. In the steady state, the superiority of the source current detection method and SVPWM control based on indefinite frequency hysteresis is verified through contrast simulation. The dynamic compensation ability of the system under dynamic condition is studied. The simulation results show that the designed detection and control system in the dissertation are correct. On this basis, the hardware experimental platform of active power filter of SVPWM control based on indefinite frequency hysteresis is designed. The experimental data shows the active power filter designed in this dissertation can effectively compensate the harmonic component of the power grid. The harmonic element of the power grid is observably reduced after it is come into use.