Application And Research Of Hybrid Active Filter In Low-voltage Distribution Network

The nonlinear devices are used widely, resulting in a large number of harmonics in low voltage power grid. The harmonic poses a huge threat to the power quality in the grid. Therefore, it is necessary to design a device to treat the harmonic in low voltage power grid. An economic and feasible hybrid active power filter is designed according the character of harmonic in the low voltage power grid. Major design work is included in the following aspects.Because of with large capacity, the cost of traditional active power filter is high.Therefore, one topological structure is put forward to reduce the size of the active power filter from the perspective of economy. 5 and 7 times harmonic passive filter and active filter are in parallel in this structure; while 11 series resonance branch shares part of the voltage of active filter. At the same time series with the fundamental resonance branch makes the fundamental voltage on the resonance branch and decrease fundamental frequency current of the active filter. The parameters of its various elements are calculated and selected.To determine the detection method of harmonic filter. This paper analysesp qi ?i harmonic detecting method based on instantaneous reactive power theory and the theory of detection method based on adaptive. Through the simulation and comparison, the adaptive detection method, which has the advantages of fast speed of current tracking and high accuracy of the compensation, is adopted. To determine the control method of filter. The voltage space vector method is adopted, after analyzing and comparing the advantages and disadvantages of the triangle wave comparison method, hysteresis control method and space voltage vector method.The hybrid active power filter simulation model is established by MATLABSimulink. Simulation results show that the hybrid active power filter can effectively filter out the harmonic in low voltage network.According to the system requirement, this paper has designed, the hardware circuit of control system with TMS320F28335 as the core, protection circuit, and the sampling circuit including the voltage sensor and the current sensor. According to the working principle of the system, this paper has designed the system software.