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Micro-grid protection method based on zero-sequence characteristic signal injection

A characteristic signal and micro-grid technology, applied in the direction of emergency protection circuit devices, electrical components, circuit devices, etc., can solve the problems of protection malfunction or refusal to operate, and cannot be applied at the same time, so as to avoid risks, delays, and fault characteristics Obvious, highly economical effect

Active Publication Date: 2021-04-09
TONGJI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, neither of these two schemes can be applied to the two operating states of microgrid grid-connected and isolated, and at the same time, it is easily affected by the characteristics of distributed power failures, resulting in false or refusal of protection.

Method used

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  • Micro-grid protection method based on zero-sequence characteristic signal injection
  • Micro-grid protection method based on zero-sequence characteristic signal injection
  • Micro-grid protection method based on zero-sequence characteristic signal injection

Examples

Experimental program
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Effect test

Embodiment 1

[0038] This embodiment provides a microgrid protection method based on injecting zero-sequence characteristic signals, including the following steps:

[0039] An inverter micro power source in the microgrid is selected as the injection source. When the microgrid is working normally, the injection source continuously injects a small-amplitude characteristic signal while outputting the power frequency current. The characteristic signal is the zero-sequence characteristic Signal;

[0040] The injection source continuously monitors the characteristic signal amplitude at its outlet, and if the characteristic signal amplitude of any phase at the outlet drops below the first multiple of its first rated value, it is judged that there is a risk of failure, and the microcomputer is started. Power grid protection; the first rated value is the characteristic signal amplitude generated by the characteristic signal at the outlet of the injection source when no fault occurs in the power grid...

Embodiment approach

[0053] As a preferred embodiment, the microgrid protection method also includes a backup protection step:

[0054] The injection source continuously monitors the characteristic signal amplitude of each phase of each line. If the characteristic signal amplitude of a certain phase of a certain line exceeds the second multiple of its second rated value, it is judged that a fault has occurred. If the fault continues to reach At the preset second time, the corresponding phase of the line is cut off, and the injection of the characteristic signal is finished, otherwise the power grid does not have a fault.

[0055] An optimum implementation manner can be obtained by combining the above preferred implementation manners, and the scheme of the optimum implementation manner will be described in detail below.

[0056] 1. Start-up criterion for characteristic signal injection

[0057] by figure 1 The microgrid with the general structure shown is taken as an example. In the microgrid, it...

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Abstract

The invention relates to a micro-grid protection method based on zero-sequence characteristic signal injection. The method comprises the following steps: selecting an inversion type micro-power supply in a micro-grid as an injection source, selecting one inversion type micro-power supply in the micro-grid as an injection source when the micro-grid works normally, and continuously injecting a small-amplitude characteristic signal while the injection source outputs the power frequency current, wherein the characteristic signal is a zero-sequence characteristic signal; continuously monitoring the characteristic signal amplitude at the outlet of the injection source by the injection source, and starting microgrid protection if the characteristic signal amplitude is reduced to be less than a first multiple of a first rated value; and after protection is started, increasing characteristic signal injection of an injection source, and measuring characteristic signals on all sections of lines of the microgrid to serve as the basis of fault positioning and phase selection. Compared with the prior art, the method has the advantages that the applicability is wide; the fault response characteristic is simple, the fault characteristic is obvious, and maloperation or refusal operation is not easy to occur; and the method has the advantages of high reliability, high sensitivity, high selectivity and the like for protecting the microgrid.

Description

technical field [0001] The invention relates to the technical field of micro-grid protection, in particular to a micro-grid protection method based on injecting zero-sequence characteristic signals. Background technique [0002] Microgrid is a small power generation, distribution, and consumption system composed of distributed power sources, energy storage systems, energy conversion devices, monitoring and protection devices, and loads. It has self-control and self-energy management functions, and can realize a large amount of renewable energy. The grid connection of energy has high practical value. As an effective means of integrating distributed energy into the grid, microgrid has become one of the key technologies in the field of new energy in the future. Therefore, it is of great significance to study the protection of microgrid for the entire energy system. [0003] Compared with the traditional power grid, the microgrid has many different characteristics, such as the ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26H02J3/38
CPCH02H7/263H02J3/381H02J3/388H02J2300/20
Inventor 张米牟龙华赵怀健方重凯欧锐张琳希
Owner TONGJI UNIV
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