Research Of Three-Level Active Power Filter Applied In Micro Grid

With the successful connection of micro power grid and large power grid, the structure of the power system and load of the structure and types are increasingly complex. Large numbers of converters in micro grid insert and cut from large power grid frequently and the loads of micro power grid rapidly change, the quality of the power is more and more caused the attention of people. To be better solve the harmonic and reactive power problems in micro grid, realizing the application of renewable energy and improving the effective utilization of energy, this paper expounds the micro grid background, on the basis of analysis of the micro grid power quality problems and the present situation of research, designed three level active power filter which is suitable for the micro grid, then puts forward the harmonic detection method based on Hilbert-Huang transform, and the traditional three level modulation algorithm of active power filter are studied, and based on the improvement of modulation algorithm is proposed for three level CLP potential balance modulation algorithm,solve the CLP potential balance problems. The algorithm is verified by simulation and experiment.First, analyzed the topology of three level active power filter corresponding to the micro grid, on the basis of analysis the principle of mathematical modeling, completed the parameters of the main circuit components selection and the power circuit. Then researched harmonic detection algorithm of active power filter which is used in micro power grid, aiming at the particularity of micro grid, harmonic detection based on Hilbert-Huang transform algorithm is proposed, and according to the change of micro power grid harmonic, the algorithm combined with theinstantaneous reactive power detection method for three level of active power filter harmonic detection algorithm is proposed.Then, the three level modulation algorithm of active power filter is studied, first analyzes the traditional three-level SVPWM modulation algorithm principle and existed problems, then on this basis, this paper proposes a simplified SVPWM modulation algorithm, and through adjusting the modulation algorithm, realized the tri-level CLP potential balance of active power filter.Finally, set up three level model of active power filter in Simulink, the simulation analysis of the micro grid harmonic compensation effect are made under different load conditions. And designed an experimental environment which includes grid, micro source and nonlinear load, applied preceding detection and control algorithm in this article method to the experimental System, experimental results and data show that the control algorithm designed in this paper can complete the micro grid current harmonic compensation, and has the good effect.