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Negative feedback virtual impedance control method for LCL type grid-connected converter

A technology of virtual impedance and control method, applied in the direction of AC power input conversion to DC power output, AC network circuit, single-network parallel feeding arrangement, etc. Impedance, loss reduction, cost reduction effect

Active Publication Date: 2021-10-08
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, the article adopts the method of sampling the capacitor current and feeding it back to the control terminal, which is equivalent to the effect of connecting resistors in parallel at both ends of the filter capacitor, but in fact it is difficult to obtain the capacitor current, which will increase additional costs

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  • Negative feedback virtual impedance control method for LCL type grid-connected converter
  • Negative feedback virtual impedance control method for LCL type grid-connected converter
  • Negative feedback virtual impedance control method for LCL type grid-connected converter

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Embodiment Construction

[0050] The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0051] Such as figure 1 As shown, the control method of the negative feedback virtual impedance of the LCL type grid-connected converter provided in this embodiment is as follows:

[0052]Sampling the grid side current I of the LCL type grid-connected converter 2 , on the grid side current I 2 with a given value I ref Perform comparison to obtain a comparison signal, and then send it to the current regulator to obtain the first error signal; sample the terminal voltage U of the filter capacitor of the LCL filter in the LCL grid-connected converter C , and send it to the voltage loop negative feedback control link G VF (s) Obtain the second error signal, through the voltage loop negative feedback control link G VF (s) The suppression of resonance peaks is achieved, a...

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Abstract

The invention discloses a negative feedback virtual impedance control method for an LCL type grid-connected converter, and the method comprises the steps: controlling the capacitor voltage of an LCL type filter in the LCL type grid-connected converter through a voltage loop negative feedback control link, increasing the damping of a system, achieving the suppression of a resonance peak existing in a conventional LCL type filter, and achieving the control of the negative feedback virtual impedance of the LCL type grid-connected converter. The damping effect that resistors are connected to the two ends of the filter capacitor in parallel is achieved, namely virtual impedance is achieved. Compared with a traditional passive damping method and a capacitive current feedback active damping method, the system loss is reduced, the total cost is reduced, and the effect of better suppressing the resonance peak is achieved.

Description

technical field [0001] The invention relates to the technical field of grid-connected converter current control, in particular to a method for controlling negative feedback virtual impedance of an LCL-type grid-connected converter. Background technique [0002] Solar energy is one of the most important sources of renewable energy, and converting it into electrical energy and utilizing it is a direction that countries all over the world have been paying attention to and researching. Photovoltaic inverter control technology is a "bridge" to ensure that the electric energy converted from light energy is smoothly integrated into the grid, and the filter is an indispensable part of this "bridge". [0003] At low frequencies, the amplitude-frequency curve of the LCL filter is attenuated at -20dB / decade, and the phase angle is -90°. As the frequency increases, a resonance peak will appear on the amplitude-frequency curve at the resonant frequency, and the phase angle The jump beco...

Claims

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Application Information

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IPC IPC(8): H02M1/12H02M1/32H02M7/5387H02J3/38H02J3/01
CPCH02M1/12H02M1/32H02M7/53871H02J3/381H02J3/01H02J2300/24Y02E10/56
Inventor 杜贵平朱天生杨子江
Owner SOUTH CHINA UNIV OF TECH