Research On Active Power Filter(APF) And Its Applications In The Low-voltage Grid

At present,electric power system pollution of harmonic is more and more serious and it has been a enormous hazards. The reason of causing this phenomenon is that electronics equipment is widely used in all kinds of trade. Now harmonic has seriously influence the normal operation of power equipment in the power grid. If the harmonic is not eliminated, there will be a great threat on the whole power grid.Active power filter(APF) is better harmonic compensation device and can compensate mutative harmonic. The basic principle of compensation is to detect harmonic current from the compensation object and then to generate compensation current which has equal size to the harmonic current and opposite phase by the compensation device so that the harmonic current of the system is offset.The main research aim of this thesis is APF application in the low-voltage grid, harmonic detection and control methods should be carefully researched.Next,the research work has the following several aspects:.At first, this paper introduce the harm of harmonics, the measures of eliminating harmonics and the research status of eliminating harmonics and developmental tendency at home and abroad.Secondly, the harmonic detection of APF is of great concern, so detection principle and selection algorithm should be carefully studied. This thesis selected qpii ? harmonic detection which is the most widely used at present. When the waveform of the source in the grid distort, this method can still rightly reflect the harmonic component because qpii ? method generate sinusoidal signal through PLL that has no direct relation to actual voltage. The simulation verifies the correctness of qpii ? detection.Thirdly, compensating current control algorithm of APF is selected as the research object, so the research on control algorithm must be careful. The current frequently-used control algorithm all have each merits and drawbacks, I finally select space vector pulse width modulation based on compensatory equipment and capacity. We improving detection link through adding PI adjusting link. If the reasonable parameter of PI is set, the voltage of DC side capacity will be stable.The simulation experiment verify that APF designed by this paper has good performance.At last, I design the major component of the hardware and software of APF according to successful simulation experiment. The design of hardware are signal detection and adjusting circuit、the module of capture and PLL、the driving module and inverting module. TMS320F2812 DSP is used as the module of computing control. The design of software are system initialization、capture interrupt、AD sampling.