Energy Storage Inverter Lcl Filter Parameter Optimization And Current Control Stability Analysis

In this era, a rapid transition to clean energy sources is urgent, among which wind and solar power system is promising. But effected by whether and other factors, this class of distributed power generation systems are unable to supply enough electricity during the peak period and fail to work at full-power during the electricity trough. This problem hinders application seriously. To resolve it, Energy Storage Inverter has been proposed. Through its two-way flow with distributed electricity grid, it can achieve the purpose of eliminating peak and filling the through for distributed power generation system. For the research focus of Energy Storage Inverter, in this paper optimization on the design of LCL filter parameters is studied and the stability of the current controlling of the energy storage inverter system is assessed.Due to the advantages on size and cost of the LCL-type filter compared with the L-type filter, LCL has become a more popular filter structure in recent engineering applications. But as it involves third-order filter characteristics and multiple interactive filter parameters, difficulty exists in actual design. Here in this paper, the design methods of LCL parameters are intensively analyzed and summarized, an new design method on optimizing index of equivalent total capacity of all filter components is introduced, and based on this design method, the attenuation of the harmonic current to the output of the filter is optimized, then we can obtain a set of filter parameters with better filtering effect. It offers a good guide to actual engineering applications.Meanwhile, in-depth study on the stability of the current controlling based on the system with LCL filter is made. Firstly, considering the accuracy of the analysis in the discrete domain of the system with pure delay, analyze the stability of current controlling under the two kinds of current feedback mode. Then according to the result that energy storage inverter is unstable under the Inverter side current feedback mode, the influence of damping control to the stability is analyzed thoroughly. According to its cause, a novel band-pass filter damping control method is proposed. Lastly, in the way of a passive damping, a PI parameters design method based on the root locus is put forward and the relationship between the series resistance value and current controlling stability is assessed, and the influence of grid impedance to the current controlling stability is studied.The methods and conclusions in this paper is verified via Energy storage inverter simulation model built by MATLAB-simulink and Experiment to determine its correctness.