LCL filter parameter optimization method under condition of considering harmonic stability of VSC system

Abstract

The invention relates to an LCL filter parameter optimization method under the condition of considering harmonic stability of a VSC system. The method comprises the following steps: 1, establishing anequivalent impedance model for a VSC grid-connected system; 2, obtaining a positive network damping criterion for the equivalent impedance model of the step 1 and taking the positive network dampingcriterion as a system stability judgment basis; 3. combining the external characteristic requirements of the LCL filter and the positive network damping criterion as the constraint conditions for LCLfilter design; 4. determining the optimization objectives and establishing a multi-objective optimization model of LCL filter parameters in combination with constraint conditions; and 5. using the MOEA / D algorithm to solve the optimization model and obtaining the optimized LCL filter parameters. Compared with the methods in the prior art, the method has the advantages of high optimization rate, simple calculation and the like.

Description

technical field [0001] The invention relates to the technical field of grid-connected inverters, in particular to a method for optimizing parameters of an LCL filter under the condition of harmonic stability of a VSC system. Background technique [0002] With the rapid development of power electronics technology, the scale of renewable energy power generation systems connected to the grid is increasing day by day. Renewable energy power generation systems based on power electronics technology have gradually replaced traditional power generation systems and become an important part of the power grid. As an important connection element between the renewable energy power generation system and the grid, the inverter will cause harmonic instability phenomenon in which the current / voltage harmonic amplitude continues to amplify under the action of dynamic interaction with the grid-connected system. When harmonic instability occurs in the system, it will cause severe distortion of ...

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Problems solved by technology

At the same time, in the process of parameter optimization design of LCL filter, a single-objective optimal design method of LCL filter parameters based on adaptive genetic algorithm is proposed in the optimal design of wind power system grid-side LCL filter based on adaptive genetic algorithm , the algorithm only takes the harmonic attenuation rate at the switching frequency as the optimization target, and there are problems such as single optimization object and poor optimization effect

In addition, in the LCL filter parameter optimization method considering the stability of the inverter under the weak power grid, some technologies have proposed a multi-objective optimization design method for LCL filter parameters based on the particle swarm optimization algorithm. Although this method comprehensively considers multiple objectives, However, it solves the single-objective optimization problem through weighting, which requires the decision maker to have sufficient prior knowledge, and there are problems such as slow convergence speed, complex calculation, and easy to fall into local optimum.

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