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Power grid impedance self-adaption based LC type grid-connected inverter dual-mode control method

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

Inactive Publication Date: 2016-02-24
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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  • Power grid impedance self-adaption based LC type grid-connected inverter dual-mode control method
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  • Power grid impedance self-adaption based LC type grid-connected inverter dual-mode control method

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Embodiment Construction

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

[0084] The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only 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 all belong to the protection scope of this patent.

[0085] O...

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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 for a grid-connected inverter system, in particular to a dual-mode control method for an LC-type grid-connected inverter based on grid impedance self-adaptation. Background technique [0002] Due to changes in the line impedance, the number of grid-connected units, the load, and the operation mode of the grid-connected inverter system, there is a certain size and changing impedance in the grid. 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 changing grid impedance, the grid-connected mode of traditional inverter current source control is seriously challenged. [0003] Aiming at the grid-connected inverter control method in the case of grid impedance, that is, the weak grid, some literatures propose methods such as adaptively adjusting control loop parameters and in...

Claims

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Application Information

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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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