Adaptive method of LCL filter based on all-pass filter

Abstract

The invention relates to an adaptive method of an LCL filter based on an all-pass filter, and belongs to the technical field of adaptive control. On the basis that an all-pass filter is used for remodeling a system phase to keep stable, poles of the all-pass filter are reconfigured to excite system resonance, an inter-harmonic algorithm is adopted to detect a current harmonic frequency during resonance, and the frequency is matched with a system 0dB ride-through frequency under different power grid impedances, so that detection of a power grid impedance value can be realized. After the impedance value of the power grid is obtained, the system can obtain the maximum amplitude margin in a mode of configuring the poles of the all-pass filter again, and the stable operation of the system is ensured. The adaptive control is realized by reconfiguring the poles of the all-pass filter after the impedance of the power grid is detected, and no extra algorithm is used to increase the calculated amount of the system. The method has the advantages of strong pertinence, low cost and high efficiency, and can realize strong robustness control on a system using the LCL filter for filtering with relatively high efficiency.

Description

technical field [0001] The invention belongs to the technical field of adaptive control, and in particular relates to an adaptive control method for an LCL filter. Background technique [0002] In the case of large-scale changes in grid impedance, for a system that uses LCL filters for filtering, if a controller with fixed parameters is used, it is difficult to optimize the control performance indicators of the system, and in severe cases it will lead to system instability. In order to ensure the stable operation of the system under the condition of large-scale changes in grid impedance, it is necessary to adopt adaptive control according to the change of grid impedance to provide guarantee for the stable operation of the system. [0003] At present, the most common adaptive control methods are mainly divided into two categories, that is, to determine the adaptive mechanism in order to obtain a stable system that makes the error close to zero, and to obtain the ideal control...

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Problems solved by technology

[0006] In order to overcome the shortcomings of the current existing adaptive control technology, such as large amount of calculation and difficulty in ensuring system stability, the present invention provides a new type of adaptive control method for the system using LCL filter for filtering, which can effectively Overcome the above disadvantages

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