Parameter optimization method considering inverter stability under weak power grid for LCL filter

Abstract

The invention discloses a parameter optimization method considering inverter stability under a weak power grid for an LCL filter. The method comprises the following steps of S1, building an inverter grid-connected output impedance model; S2, analyzing influence of power grid impedance on stability of an inverter grid-connected system; S3, building a multi-target LCL filter parameter optimization model considering power grid impedance influence; S4, solving the optimization model by employing an improved compressibility factor method-based particle swarm optimization algorithm; and S5, optimizing the LCL filter parameter. The optimization model is suitably used for designing the LCL filter parameter under the weak power grid or a multi-inverter intensive connection condition, standard satisfaction is introduced into an estimation index, the optimization degree is quantitatively evaluated, much-aspect indexes such as filtering performance and economic cost can be compatible very well, and integral optimization on LCL filter and current ring parameters is achieved; and by the method, theoretical basis is provided for stability analysis of inverter intensive connection under a new energy station, and guidance is provided for designing the grid-connected inverter parameter under the weak power grid.

Description

technical field [0001] The invention relates to the technical field of analyzing the grid-connected power quality of multiple inverters, in particular to an LCL filter parameter optimization method considering the stability of inverters under a weak grid. Background technique [0002] In response to climate deterioration and resource depletion, the proportion of distributed power generation systems based on wind energy, solar energy and other renewable energy sources in the power system is increasing day by day, and the operation of a high proportion of new energy power has become the norm. As the connection unit between the new energy power generation system and the grid, the grid-connected inverter is responsible for converting DC power into high-quality AC power and feeding it into the grid. The LCL filter has a good high-frequency harmonic suppression effect It is widely used in grid-connected equipment. [0003] Because the amplitude-frequency characteristic of the LCL...

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Problems solved by technology

[0007] The above-mentioned LCL filter optimization methods are all independently analyzed and calculated under the ideal power grid, and it is easy to cause the designed inverter to fail to operate stably in the case of a high proportion of the electric field of the new power supply.

[0008] At present, considering the limitation of filter parameters by current control, an integrated design method of LCL filter and controller parameters is proposed for the control scheme of single inverter side current feedback, which simplifies the design process, but does not consider weak current in the design process. Therefore, it is necessary to optimize the parameters of the LCL filter based on the grid-side current feedback scheme widely used in engineering under the premise of considering the grid impedance and current control

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