Composite type island detection method based on phase deviation and frequency variation

A technology of frequency change and phase offset, which is applied in power supply testing, emergency protection circuit devices, electrical components, etc., can solve problems such as inability to solve sensitivity and misoperation, and achieve the effect of improving sensitivity

Inactive Publication Date: 2010-02-17
SHANDONG UNIV +1
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Problems solved by technology

The contradiction between sensitivity and misoperation cannot be solved only by detecting phase shift

Method used

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  • Composite type island detection method based on phase deviation and frequency variation
  • Composite type island detection method based on phase deviation and frequency variation
  • Composite type island detection method based on phase deviation and frequency variation

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Embodiment Construction

[0027] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0028] Detection principle of the present invention:

[0029] The phase offset angle Δθ is the cumulative value caused by the frequency change Δf, and its size is determined by two factors: the size of the frequency change and the duration of the change, and the relationship between them can be deduced as:

[0030] Δθ=2π∫Δfdt

[0031] It can be seen from the above formula that for the same phase offset, the duration of the frequency change is different, and the corresponding maximum value of the frequency change is also different, which can be used image 3 means, where t 1 , t 2 and t 1 ', t 2 ' are the start and end moments of the frequency change in two different situations, respectively, and Δθ is the area of ​​the shaded part in the figure. It can be seen that for the same Δθ, the corresponding maximum value of frequency change is different. ...

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Abstract

The invention discloses a composite type island detection method based on phase deviation and frequency variation. Firstly, delta theta1 and delta theta2, the motion values of two phase deviations areset, and the condition that delta theta1 is more than delta theta2 is met; when the phase deviation angle of the end voltage of a distributed generator (DG, Distributed Generator), delta theta is more than delta theta1, DG is directly judged as island operation; when delta theta is more than delta theta2 and less than delta theta1, the frequency variation value delta f is introduced as supplementary detection amount, only when the condition that delta theta is more than delta theta2 and delta f is less than delta f1 is met, delta f1 is frequency variation motion value, so that the motion of the detection device is judged as island state; the composite type motion criteria of the island detection are concluded as follows: delta theta is more than delta theta1(1) or delta theta is more thandelta theta2 and delta f is less than delta f1(2); the criterion (1) is used for island instant DG and the condition that mismatching degree of loaded active power is larger, while the criterion (2)is used for the condition that the change of the loaded active power carried by island post DG is not large, namely, the traditional phase deviation method can not detect the island state; whether DGis in the island state or not is judged by introducing frequency variation amount and combining the phase deviations and frequency variations.

Description

technical field [0001] The invention relates to the technical field of distribution network protection and control and the technical field of distributed power generation, and more specifically relates to a composite islanding detection method based on phase offset and frequency variation of a distributed synchronous generator. Background technique [0002] Grid-connected distributed power sources need to be installed with an island detection device to quickly and accurately detect the island state. Once the island occurs, take corresponding measures immediately to eliminate the possible harm caused by the island operation. Due to the different types of distributed generators (DG, DistributedGenerator) and their grid connection methods, the islanding detection methods are also different. For synchronous generators, a passive detection method based on changes in local (DG side) electrical quantities is generally used. Among them, islanding detection using DG terminal voltage...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/40
Inventor 侯梅毅高厚磊张永武胡晓东孙爱民武志刚李玉志曹华明林勇陆以军姚翔
Owner SHANDONG UNIV
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