Dual-mode control method for LC-type grid-connected inverter based on grid impedance self-adaptation

A technology of grid impedance and control method, used in photovoltaic power generation, electrical components, circuit devices, etc.

Inactive Publication Date: 2017-08-29
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0020] The technical problem to be solved by the present invention is to overcome the limitations of the above-mentioned various technical solutions. When the inverter is connected to the grid under different grid impedances, the single current source or voltage source mode can only be used in a small grid impedance change. To solve the problem of stable operation within a wide range, a LC-type grid-connected inverter based on grid impedance self-adaptation is provided to enable the inverter to operate stably in a wider range of grid impedance by switching between current source and voltage source modes. Transformer dual mode control method

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  • Dual-mode control method for LC-type grid-connected inverter based on grid impedance self-adaptation
  • Dual-mode control method for LC-type grid-connected inverter based on grid impedance self-adaptation
  • Dual-mode control method for LC-type grid-connected inverter based on grid impedance self-adaptation

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Embodiment Construction

[0083] The embodiment of the present invention provides a dual-mode control method for an LC grid-connected inverter based on grid impedance self-adaptation, so as to solve the problem that the existing inverters in the prior art are connected to the grid under different grid impedances. The current source or voltage source mode can only operate stably within a small range of grid impedance changes. The mutual switching between grid-connected modes expands the stable operation range of the inverter under different grid impedance conditions.

[0084] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative work are within the protection scope of this patent.

[0085] 1. The topologi...

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Abstract

The invention discloses a power grid impedance self-adaption based LC type grid-connected inverter dual-mode control method. According to the invention, a power grid impedance boundary value of mutual switching between a current source grid-connected mode and a voltage source grid-connected mode of an inverter is determined at first, the inverter adopts a current source grid-connected mode control method when the power grid impedance boundary value is less than a switching boundary value, and the inverter adopts a voltage source grid-connected mode control method when the power grid impedance boundary value is greater than the switching boundary value; and an impedance hysteresis loop based switching mode is adopted in order to improve the stability in switching. The method disclosed by the invention solves a defect that the inverter can only operate stably within a small power grid impedance variation range when adopting a single current source or voltage source grid-connected mode under different power grid impedance conditions, and stable operations of the inverter within a large power grid impedance variation range are realized through mutual switching between the current source power-grid mode and the voltage source grid-connected mode.

Description

Technical field [0001] The invention relates to a control method of a grid-connected inverter system, in particular to a dual-mode control method of an LC type grid-connected inverter based on grid impedance adaptation. Background technique [0002] Due to changes in line impedance, the number of grid-connected units, load, and the operation mode of the grid-connected inverter system, the power grid has a certain magnitude and varying impedance. Excessive grid impedance will reduce the bandwidth of the grid-connected inverter control system and reduce the stability of the grid-connected inverter system. Therefore, under the condition of grid impedance changes, the grid-connected mode of traditional inverter current source control is seriously challenged. [0003] For the grid with impedance, that is, the control method of grid-connected inverter in the case of weak grid, some documents propose methods such as adaptive adjustment of control loop parameters and increasing virtual im...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38H02M7/537
CPCH02J3/383H02M7/537Y02E10/56
Inventor 张兴李明刘芳徐海珍石荣亮
Owner HEFEI UNIV OF TECH
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