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Output impedance correction method for improving stability of LCL type grid-connected inverter

A technology of output impedance and correction method, which is applied in the directions of converting irreversible DC power input into AC power output, AC network circuit, single network parallel feeding arrangement, etc., which can solve engineering realization difficulties, measurement errors, inaccurate compensation, etc. problem, to achieve the effect of improving the phase angle margin, decreasing the THD value, and ensuring stable operation

Active Publication Date: 2017-08-18
HEFEI UNIV OF TECH
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Problems solved by technology

However, in the current grid-connected inverter impedance correction method, first, it is necessary to accurately measure the grid impedance, and measurement errors lead to inaccurate compensation; second, it is necessary to introduce a high-order differential link, which is difficult to implement

Method used

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  • Output impedance correction method for improving stability of LCL type grid-connected inverter
  • Output impedance correction method for improving stability of LCL type grid-connected inverter
  • Output impedance correction method for improving stability of LCL type grid-connected inverter

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Embodiment Construction

[0058] see figure 1 In this embodiment, the single-phase LCL grid-connected inverter system under a weak power grid includes: a DC source 1, an inverter bridge 2 composed of four switching tubes with freewheeling diodes, and a filter inductor L1, L2 and a filter capacitor C The LCL filter composed of the ideal voltage source U g and grid impedance Z g Composed of public grid 4, current controller 5, phase compensator 6 and SPWM generator 7.

[0059] Such as figure 1 and figure 2 As shown, the output impedance correction method to improve the stability of the LCL grid-connected inverter in this embodiment is: add a phase compensator based on the grid-connected current to the LCL grid-connected inverter with source damping, and construct a series The virtual impedance of the inverter is used to correct the impedance angle of the inverter output impedance. By improving the phase angle margin of the grid-connected inverter under a weak grid, the quality of the grid-connected ...

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Abstract

The invention discloses an output impedance correction method for improving the stability of an LCL type grid-connected inverter, which is characterized in that a grid-connected current based phase compensator is added to an LCL type grid-connected inverter containing active damping, series-connected virtual impedance is built so as to be used for correcting an impedance angle of output impedance of the inverter, the grid-connected current waveform quality of the inverter is improved through improving the phase margin of the grid-connected inverter under a weak power grid, and the system stability of the grid-connected inverter under the weak power grid is improved.

Description

technical field [0001] The invention belongs to the technical field of grid-connected inverter control, and more specifically relates to an output impedance correction method for improving the stability of a grid-connected inverter, which is used to improve the quality of the grid-connected current waveform of the inverter and improve Grid-connected inverter system stability. Background technique [0002] Distributed power generation technology based on renewable energy, such as wind energy and solar energy, is one of the important ways for human beings to deal with energy crisis and environmental pollution. As a key interface device between the distributed generation system and the grid, the grid-connected inverter's performance directly determines the quality of the grid-connected current. [0003] With the increase of distributed power grid-connected power and the wide distribution of grid-connected locations, factors such as longer transmission and distribution lines, m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/48H02J3/38
CPCH02J3/381H02M7/48
Inventor 杜燕崔林波杨向真苏建徽
Owner HEFEI UNIV OF TECH
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