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Method for eliminating secondary pulsation interference on middle DC side in two-stage grid-connected system

A secondary pulsation, intermediate DC technology, applied in the direction of single-grid parallel feeding arrangement, etc., can solve the problems affecting inverter control, grid-connected current fluctuation, reducing system dynamic response, etc., and achieve the effect of improving control performance.

Active Publication Date: 2011-07-27
BEIJING NEGO AUTOMATION TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The secondary ripple of the intermediate DC side voltage will affect the control of the inverter
And it will cause fluctuations in the grid-connected current, seriously affecting the waveform quality of the grid-connected
[0003] Traditional control methods mostly filter the intermediate DC side to ensure that the secondary ripple of the intermediate DC side voltage does not seriously affect the control. However, similar methods reduce the bandwidth and the dynamic response of the system.

Method used

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  • Method for eliminating secondary pulsation interference on middle DC side in two-stage grid-connected system
  • Method for eliminating secondary pulsation interference on middle DC side in two-stage grid-connected system
  • Method for eliminating secondary pulsation interference on middle DC side in two-stage grid-connected system

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Embodiment Construction

[0015] The method for eliminating the secondary pulsation interference of the intermediate DC side in the two-stage grid-connected system of the present invention comprises the following steps,

[0016] (1) The single-phase PWM inverter controlled by the subsequent DC / AC control module inevitably produces secondary pulsation interference in the intermediate DC link.

[0017] (2) A second harmonic compensation module is added to the front-stage DC / DC link, and the second pulsation interference is fed back to the second harmonic compensation module through filtering.

[0018] (3) The second harmonic compensation module gives the compensation signal switching command D^ref signal of the second pulsation according to the feedback, and obtains the compensation signal of the second pulsation.

[0019] (4) The compensation signal is superimposed on the original D*ref signal to become the Dref signal, which is used as the control value of the switching tube duty ratio of the previous ...

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Abstract

The invention provides a method for eliminating secondary pulsation interference on the middle DC side in a two-stage grid-connected system. The method comprises the step that because the reverse compensation of the secondary harmonic pulsation in the middle DC link is made by a secondary harmonic compensation module added in the DC / DC link at the preceding stage, the secondary pulsation interference is eliminated and the middle DC voltage is stabilized. The method has the advantages that the middle filtering link is unnecessary, and in the system, a filtering device is unnecessarily arrangedon the middle DC side; the inversion control bandwidth is not affected; and the control performance of the system is improved without adding any equipment.

Description

technical field [0001] The invention is mainly used in a two-stage single-phase converter system, and is especially suitable for a method for eliminating secondary pulsation interference on an intermediate DC side in a medium and small power two-stage grid-connected converter system similar to a photovoltaic grid-connected power generation system. technical background [0002] In the single-phase converter system with two-stage structure, the rear-stage grid-connected device (DC / AC link) adopts a single-phase PWM grid-connected inverter, because the single-phase PWM (Pulse Width Modulation, Pulse Width Modulation) converter itself Due to the limitations of the topology, there is inevitably a secondary power ripple on the intermediate DC side. The secondary ripple of the intermediate DC side voltage will affect the control of the inverter. And it will cause fluctuations in grid-connected current, which seriously affects the waveform quality of grid-connected. [0003] Tradi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
Inventor 童亦斌马琳卢婷雷涛王子洋刘京斗
Owner BEIJING NEGO AUTOMATION TECH