| Harmonics in power system directly affect people’s life and the economic development of the society. So, how to filter harmonics in power system has been the focus of the field of the power quality. Conventional passive filter was widely used because of simple structure, low cost and so on. The double-tuned filter has more economic advantages compared to single tuned filter, so it has been an important development direction that double-tuned is extensively used to filter harmonics and compensate reactive power. Researches on double-tuned filter designing method and detuning will be an important direction.In this paper, according to the question of parameters of double-tuned filter, after summarizing designing methods at home and abord, in-depth theoretical analysis and technique research on double-tuned filter has been done from the perspective of tuning frequency. Impedance based on tuning frequency was introduced, working principal was analyzed and the new method based on tuning frequency was proposed. Second, the common cause which leads to double-tuned filter detuning was analyzed, the effect caused by system frequency drift,voltage change, load change and component parameter drift and the solution was given.Simulation platform is built by using MATLAB7.11/Simulink in the background of harmonic suppression in plating base.Impedance and filter effect of5th and7th tuned filter was shown via simulation. Comparison between double-tuned filter and two parallel single tuned filters was done in filtering effect and robustness. At last, the affect caused by system frequency, voltage changing, load changing and component parameters drift was displayed by simulating. The method to solve the detuning problem was proved to be successful by simulation.The method based on tuning frequency has a clear thinking, which avoids the complex process of dealing with equations and has a significant scientific guiding significance. The researches on self-tuning is helpful for its widely use in society. |
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