Lcl Filter Grid Inverter Direct Current Control Research

With the constantly consumption of fossil energy, development and utilization ofthe clean and renewable energy such as wind power and solar energy are more and moreimportant, because of the weather season and other factors, the power generated bywind and solar are not accord with the grid demand. Energy storage power station canrealize the complementary of new power generation systems and traditional powergeneration system, and plays an important role in cutting peak and valley of gird,stabilizing power grid, using renewable energy.As an important component of energy storage system, bi-directional currentconverter plays an important role of AD&DA, and stores power in batteries when thegird has more energy, and transmits power to the grid when the gird needs more energy.National relevant standards for access to the grid have strict harmonic requirements.LCL filter is better than L filter in the high frequency attenuation capability, and beengineering application gradually, so this research object are bi-directional currentconverter base on LCL filter.Because of the filter capacitance and the filter inductance, grid side current andconverter side current is different, so current feedback are two kinds such as andcommunication power grid side by side two kinds. Two different current feedbacks havedifferent system control targets. Firstly, to deduce the control object transfer functionaccording to system control structure. Secondly, to design current loop controlleraccording to different control object. Thirdly, to analyse the system control structurewith the controller, and analyse the dynamic and static characteristic through the openloop system root locus and potter figure. To change the filter parameters and thenetwork voltage, compare the system robustness of two current feedbacks. Doemulation of two current feedback systems such as load switch in the Matlab software,and verify the correctness of the analysis. Finally, do experiments about two current feedback control methods in10KW converter experimental platform and prove thecorrectness of the analysis and emulation.