The Study On Adjusted Parallel Hybrid Power Filter

People at early realize the problems of harmonics. Especially, the quick development of technology of electricity and electron and the application of power facilities and electronics make the harmonics and it's harm increasingly serious, which makes all the countries on earth give much caring and importanceto the problem.In industry , large quantity slow or cyclic loads are connected with industry power web. When they work, the reactive power is very frequent and severe, which makes the system's voltage arise fluctuate , lightning and unbalanced. At the same time, large quantity high frequency harmonics pour in the power system. All of these seriously effect the system's electrocity power quality and threaten the power system's stable run.Now industry fliters and equipments have achieved enormous development, but there are many defect.Still voltaic compensator SVC with TCR and FC causes comparatively large harmonics when it compensates the reactive power. It makes the equipments huge, the controlling complex, the realiability low and the response velocity slow.Still voltaic generator (SVG) with GTO or IGBT and PWM can tail the fluctuation of load .But for single element, the capacity is smaller, the level of voltage and current is lower and the prise is higher.When apply to high-voltage and large-capacity condition, the system needs many elements, and requires better the technology of average-voltage and average-current. So it is difficult for SVG to apply to this case.Active power filter isn't containing large-capacity reactive power element, so it can be designed smaller and more economic . But the capacity is be limited.Especially, the development of high-voltage filters and equipments is in a slower level, it is essential to strengthen the study and application of the high-voltage filters and equipments.Hybrid power filter being composed of ractive power filter and active power filter integrates the advantages of both, so it can be applied to different voltage and capacity situation and becomes the new study field of industry filters and equiopments. In this paper, the study is worked to the tranditional hybrid power filter, and a improved design is protosed to overcome the defect of fliters and equipment.The reactive power filter is mainly to achieve the compensation to harmonic. For better following the changes of the current power web's harmonics, the design of the reactive power filter impoves tranditional filters that use the constant structure and employs multi-structure to different harmonics situation. It is designed to overcome the defect that the filters can't well follow the hatmonics when time is different and harmonics sources are different.The active filter mainly works as aided filter as well as controlling the reactive power filter's compensating result. Thus the defect that the active power filter can't bear large voltage is overcome. Based on this new topology, three control strategies are introduced, that is, detecting the load harmonic currents, detecting the line harmonic currents and detecting both of them. On the detailed study of these control strategies, the complex one has been verified the best considering either the filtering effect or the vibration suppression. So this paper selects the complex controlling style.Finally.the paper works out signal's waveform by calculating and emulating withcomputer,and tests the design is feasible and reliable.