Islanding detection method and device for direct-current system

An islanding detection, DC system technology, applied in the direction of measuring devices, measuring electricity, measuring electrical variables, etc., can solve the problem of islanding effect in DC microgrids, and achieve the effect of ensuring islanding detection efficiency and no detection blind spots.

Active Publication Date: 2017-01-25
XUJI GRP +3
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The purpose of the present invention is to provide an islanding detection method and device for a DC system to solve the problem of detecting the islanding effect of a DC microgrid

Method used

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  • Islanding detection method and device for direct-current system
  • Islanding detection method and device for direct-current system
  • Islanding detection method and device for direct-current system

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Embodiment Construction

[0026] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

[0027] Embodiments of the islanding detection method for DC systems of the present invention:

[0028] Such as figure 1 The shown AC-DC hybrid microgrid, photovoltaic DC converter and energy storage DC converter can all operate in grid-connected mode. Taking photovoltaic DC converter as an example, the DC large After the converters are all disconnected, an island is formed between the photovoltaic DC converter and the DC load as shown by the dotted arrow in the figure.

[0029] The island detection process of the present invention is as follows image 3 As shown, the step of judging the suspected island: inject the first power disturbance into the DC microgrid system, such as Figure 4 As shown, when the time axis in the figure is 0.3S, the disturbance of the first power is added to reduce the voltage of the DC microgrid, and the change a...

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Abstract

The invention relates to an islanding detection method and device for a direct-current system. The method comprises steps as follows: first power disturbance is injected into a direct-current micro grid, and suspected islanding is diagnosed when the variation of the grid-connected voltage is detected to be higher than or equal to a first admissible value of a voltage difference absolute value within set time or set times; second power disturbance is injected into the direct-current micro grid, and the fact that islanding occurs to the direct-current system is determined when the variation of the grid-connected voltage is detected to be higher than or equal to a second admissible value of the voltage difference absolute value within set time or set times. Accurate protection criteria are provided for off-network of a direct-current transformer, the islanding detection efficiency of the direct-current system is guaranteed, and a non-detection zone is avoided.

Description

technical field [0001] The invention relates to an island detection method and device for a DC system, and belongs to the field of distributed power generation and AC / DC hybrid microgrids. Background technique [0002] With the rapid development of distributed power generation and AC / DC hybrid microgrids, the problem of island effect in microgrids has become increasingly prominent. [0003] The island effect usually refers to that in the AC power grid, when the power supply trips due to a fault accident or power outage maintenance, the distributed grid-connected power generation system at each user end fails to detect the power outage state in time and cuts itself off from the mains network, thus forming a network caused by A self-sufficient power supply island composed of distributed grid-connected power generation system and surrounding loads. Once the island is generated, it will cause many hazards, such as impacting the power grid protection device, causing voltage and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00
CPCG01R31/00
Inventor 徐军李瑞生王强唐保国翟登辉郭宝甫田盈王卫星岳帅王小凯张鹏
Owner XUJI GRP
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