Isolated island detection anti-misoperation locking method according to frequency and current change time sequence

A technology of island detection and current change, which is applied in the measurement of electrical variables, monitoring of photovoltaic systems, and measurement of electricity, can solve problems such as misjudgment, achieve the effect of simple principle, reduce the possibility of misjudgment, and avoid misoperation

Active Publication Date: 2017-12-29
NARI TECH CO LTD
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the harmonic voltage combined with the frequency island detection method mentioned in the above background technology may cause misjudgment. The present invention proposes an island detection anti-mislocking method based on frequency and current change timing

Method used

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  • Isolated island detection anti-misoperation locking method according to frequency and current change time sequence
  • Isolated island detection anti-misoperation locking method according to frequency and current change time sequence
  • Isolated island detection anti-misoperation locking method according to frequency and current change time sequence

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Embodiment 1

[0021] In order to better understand this embodiment, an islanding detection method formed by combining harmonic voltage and frequency changes before and after the islanding is described first. Many new island detection methods have been derived on the basis of traditional island detection methods. At present, there is an island detection method that uses frequency and harmonic voltage changes before and after the island. After the island, the harmonic voltage increases and the frequency shifts. , the combination of the two can effectively detect the island, and the frequency does not exceed the threshold when the background harmonic is large, which can avoid misjudgment. Action threshold, thereby narrowing the detection blind zone, avoiding the problems existing when the over / under frequency detection and harmonic detection methods are used alone. Specific steps are as follows:

[0022] Step 1: Set the inverter switching frequency as f C , modulation frequency f S 50Hz, co...

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Abstract

The invention discloses an isolated island detection anti-misoperation locking method according to a frequency and current change time sequence and belongs to the photovoltaic power generation system technology field. Aiming at misjudgment under a power grid frequency deviation, according to a frequency and harmonic wave voltage change time sequence relation, anti-misoperation locking is performed. If a frequency is changed firstly, a power grid frequency change is determined and the change is not caused by an isolated island. Aiming at misjudgment during transformer air drop, according to an air drop currentless condition of a transformer, the anti-misoperation locking is performed. In the invention, harmonic disturbance when a power grid frequency deviates and misoperation caused by transformer air drop and the like are effectively solved, a possibility of the misjudgment is reduced and a certain practical engineering value is possessed.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation systems, and more precisely, the invention relates to an island detection anti-mislocking method based on frequency and current change sequence. Background technique [0002] The occurrence of isolated islands will bring a series of problems, and the grid-connected photovoltaic power generation system should have the ability to detect and protect isolated islands. Among the common islanding detection methods, there are various problems whether it is over / under frequency, over / under voltage islanding detection method or pure harmonic islanding detection method. Combining the changes of harmonic voltage and frequency before and after the island can constitute a new type of islanding detection method, which detects the island when the harmonic voltage rises after the island and the frequency shifts to a certain extent. Since the frequency does not change when the background har...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/08H02S50/00
CPCG01R31/088H02S50/00Y02E10/50
Inventor 陈汹陈永华王森唐冠军李雪明许士光薛峰罗剑波陈勇邹亚平周汝勇
Owner NARI TECH CO LTD
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