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A DC bus voltage control method for AC-DC hybrid microgrid

A DC bus voltage, AC and DC hybrid technology, applied in the field of smart grid, can solve problems such as increasing system instability, and achieve the effects of avoiding frequent charging and discharging, improving efficiency, and increasing stability

Active Publication Date: 2018-08-03
XUJI GRP +3
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a DC bus voltage control method for an AC-DC hybrid microgrid to solve the problem in the prior art that frequent charging and discharging increases system instability when controlling the DC bus voltage adjustment

Method used

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  • A DC bus voltage control method for AC-DC hybrid microgrid
  • A DC bus voltage control method for AC-DC hybrid microgrid
  • A DC bus voltage control method for AC-DC hybrid microgrid

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Embodiment 1

[0024] The invention aims at monitoring the DC bus voltage in real time by a two-stage power flow converter in an AC-DC hybrid microgrid, and automatically performing charging and discharging logic state conversion.

[0025] The following focuses on the detailed description of the AC / DC power flow controller's self-regulation of the DC bus voltage in the grid-connected mode:

[0026] Such as figure 1 As shown, in order to avoid frequent charging and discharging of the AC / DC power flow controller, the present invention designs an idle mode regarding the drooping characteristics of the DC bus voltage. When the DC bus voltage is at U dc-ref011 ≤ U dc ≤ U dc-ref01 When , the AC / DC power flow controller is in the inverter mode to send the excess power in the DC bus system to the AC system; when the voltage is at U dc-ref011 ≤ U dc ≤ U dc-ref01 When the AC / DC power flow controller is in idle mode, it will not charge or discharge; when the voltage is at U dc-ref022 ≤ U dc ≤ U ...

Embodiment 2

[0039] In this embodiment, the grid-connected control mode is the same as the grid-connected mode in Embodiment 1. The only difference lies in the control mode when off-grid. It will be described in detail below.

[0040] Such as Figure 5 As shown, the specific process is as follows: First, check whether the AC-DC hybrid microgrid is in the grid-connected operation state. If the AC-DC hybrid micro-grid is in the grid-connected operation state, the AC / DC power flow controller will work to stabilize the DC bus voltage to the voltage Set value U dc_ref ;At this time, the DC voltage loop of the DC / DC controller is in a saturated state due to the influence of the integral term in the PI regulator, and has no effect on the stable regulation of the DC bus voltage; if the AC-DC hybrid microgrid is in the off-grid operation state, then Check whether the DC / DC controller in the DC microgrid is in the charging state; if the DC / DC controller is not in the charging state, and the DC bu...

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Abstract

The invention relates to an alternating current / direct-current hybrid microgrid direct-current busbar voltage control method. According to the method, under a grid-connected state, an alternating current / direct-current power flow controller adjusts the voltage of a direct-current busbar, and the voltage of the direct-current busbar under the grid-connected state is divided into three intervals, namely, an inversion mode, an idle mode and a rectification mode with set voltage Udc adopted as reference, voltage intervals corresponding to the three modes are [Udc-ref01, Udc-ref02], [Udc-ref011, Udc-ref01] and [Udc-ref022, Udc-ref011]; control is carried out according to droop control characteristics, and therefore, the voltage of the direct-current busbar is adjusted and is made to be decreased under the inversion mode, the voltage of the direct-current busbar is not adjusted under the idle mode, and the voltage of the direct-current busbar is adjusted and is made to be increased under the rectification mode; and in an off-grid state, control on the voltage of the direct-current busbar is realized in a manner that independent bias stabilization control is performed on the voltage of the direct-current busbar by a plurality of alternating current / direct-current controllers connected with energy storage equipment. With the alternating current / direct-current hybrid microgrid direct-current busbar voltage control method adopted, frequent charging and discharging which is caused by a situation that adjustment is performed as soon as the voltage of the direct-current busbar fluctuates can be avoided, and therefore, the stability of a system can be improved, and the service life of the alternating current / direct-current power flow controller can be prolonged.

Description

technical field [0001] The invention relates to the technical field of smart grids, in particular to a method suitable for autonomous deviation stabilization control of DC busbar voltage in AC-DC hybrid microgrids. Background technique [0002] It is difficult for a single DC microgrid or AC microgrid to meet the high-efficiency power consumption needs of various loads, resulting in an AC-DC hybrid microgrid that integrates AC microgrids and DC microgrids. Adopting the AC-DC hybrid power supply mode is more conducive to the integration of various distributed power generation, forming a situation where several AC-DC hybrid micro-grids work in harmony with the large power grid. one of the effective ways. However, the system structure of the AC-DC hybrid microgrid is relatively complex, and there are many control objectives, which increase the difficulty and complexity of the stable operation and coordinated control of the system, especially the DC bus voltage stability contro...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/02
Inventor 毋炳鑫谢卫华李献伟武乃虎田盈王毅
Owner XUJI GRP
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