| Active power filter is considered as the most effective method to harness the serious "power pollution". This paper's purpose is to provide a new control scheme and realization method based on the studying of the current control method and realization.Firstly the background, development and future prospect of active power filter is described in detail. And it comes to the conclusion that active power filter has many merits and functions including harmonic compensation, reactive power compensation, voltage regulation and flicker suppression. However, active power filter hasn't been perfect. More efforts still have to be done in circuit topology and control technique.Based on the analysis of various harmonic detection methods and the drawback of instantaneous reactive power theory, the concept of power factor is introduced into the control system of active power filter. The harmonic and reactive current detection technique based on unity power factor and its application in shunt active power filter is described in detail. This method has better applicability. The transient characteristic of the detection method is analyzed and the detailed method of shortening the detection delay is provided.The concept of unity power factor can also be applied to the control of series active power filter. And the control method is provided. The characteristic of harmonic source is analyzed and corresponding active power filter topology should be adopted.In order to avoid the system instability resulted by the big proportional coefficient in the control of hybrid-shunt active power filter, a new control method is provided. It uses the detection of harmonic voltage and avoids the matter of proportional coefficient. The power rating of the active power filter is greatly reduced by controlling the base voltage on the active power filter.A shunt active power filter is applied in the fisher boat in order to suppress the harmonic produced by the sleeve-fish troll machine. The design scheme of the shuntactive power filter is provided.Many experiments are done on the experimental equipment of shunt active power filter based on DSP. The harmonic and reactive current detection technique based on unity power factor and the shunt active power filter based on it are tested. And satisfactory result is drawn. The results verify the effectiveness of harmonic detection and control method based on unity power factor and validity of theoretical analysis. |
