Serial-parallel impedance reshaping method of smooth busbar voltage

A bus voltage and parallel technology, applied in the direction of AC network voltage adjustment, circuit devices, AC network circuits, etc., can solve the problems of impedance amplitude change, deterioration of bus voltage quality, frequency offset, etc., to reduce output impedance, improve Bus voltage quality, the effect of reducing the distortion rate

Active Publication Date: 2018-10-16
HUNAN UNIV
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  • Description
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  • Application Information

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Problems solved by technology

However, the droop control makes the frequency of the inverter output voltage shift, resulting in a change in the magnitude of the equivalent output impedance of the inverter, which may further deteriorate the quality of the bus voltage

Method used

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  • Serial-parallel impedance reshaping method of smooth busbar voltage
  • Serial-parallel impedance reshaping method of smooth busbar voltage
  • Serial-parallel impedance reshaping method of smooth busbar voltage

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Embodiment Construction

[0028] figure 1 It is a structural diagram of a multi-LCL inverter parallel system under the high-proportion nonlinear load condition of the microgrid mentioned in the present invention, including m (m=1, 2, 3...) micro-sources with LCL inverter interfaces , several resistance-inductive linear loads and high-permeability nonlinear loads. For a single LCL inverter: its input terminal is connected to the DC micro-source composed of DG and energy storage device; its output terminal is filtered by LCL filter to filter out high-order harmonics, and then through the line impedance Z line Imported to the AC common bus. Among them, u o and i o are the output voltage and current of the LCL inverter, respectively; i L Inverter side inductor current of the inverter; u C is the filter capacitor voltage of the inverter; L 1 and L 2 Respectively, the inverter side and the grid side filter inductance of the inverter; C is the filter capacitor of the inverter; the line impedance Z li...

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Abstract

The invention discloses a serial-parallel impedance reshaping method of smooth busbar voltage, and is used for reducing equivalent output impedance under the condition of micro-grid drooping frequencydeviation and then suppressing the busbar voltage distortion caused by the non-linear load. The serial-parallel impedance reshaping method of the smooth busbar voltage has the advantages that serialconnection virtual resistance and parallel virtual admittance are combined, the output impedance of an inverter on a fundamental frequency of 50 Hz and integer subharmonic frequency is kept invariable, the equivalent output impedance after an output frequency offsets is reduced, thereby effectively improving the busbar voltage quality of a micro-grid inverter parallel system under the high-proportion non-linear load condition.

Description

technical field [0001] The invention relates to the field of harmonic suppression of micro-grid bus voltage, in particular to a series-parallel impedance remodeling method for smoothing bus voltage. Background technique [0002] As a small-scale power generation and distribution system that integrates distributed power sources, energy storage devices, energy conversion devices and local loads, the microgrid can not only run in parallel with the distribution network, but also operate at the point where the distribution network fails or distribute power. It is an effective way to realize the active distribution network. For a multi-LCL inverter parallel system in an island microgrid, the harmonic current generated by a high proportion of nonlinear loads will cause a large harmonic voltage drop on the output impedance of the inverter, seriously deteriorating the quality of the bus voltage. The output voltage control strategy based on proportional-repetitive control can effecti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/12
CPCH02J3/12H02J2203/20
Inventor 周乐明姜捷陈燕东伍文华周小平杨苓谢志为刘傲洋郭健
Owner HUNAN UNIV
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