Island effect detection method based on active frequency deviation and its device

A technology of active frequency offset and islanding effect, applied in emergency protection circuit devices, electrical components, etc., to reduce impact, reduce harmonics, and speed up detection

Inactive Publication Date: 2008-02-13
JIANGSU NARI TURBOSTAR ELECTRIC +2
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0034] 2. Disadvantages of AFD method
[0038] The above shortcomings show that the A...

Method used

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  • Island effect detection method based on active frequency deviation and its device
  • Island effect detection method based on active frequency deviation and its device
  • Island effect detection method based on active frequency deviation and its device

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Experimental program
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Effect test

Embodiment 1

[0062] Step 1: Taking 25 cycles as a large cycle, the chopping rate cf=0 in the first 15 cycles, and detect the change trend of the frequency at the same time. The change trend of the frequency belongs to the situation that the frequency has an upward trend. Add the frequency disturbance with chopping rate cf to the grid frequency, and the initial value of chopping rate cf is cf max is a positive value, and the trend of frequency change belongs to the situation that the frequency has a downward trend, and the frequency disturbance of the chopping rate cf is also added to the grid frequency in the last 10 cycles, and the initial value of the chopping rate cf c fmin is a negative value,

[0063] The detection method of the above-mentioned frequency change trend is as follows: within the first 15 cycles in each large cycle, use the phase-locked circuit of the grid-connected inverter system to detect the frequency value of the cycle, and set the initial frequency of the voltage cy...

Embodiment 2

[0072] Including a control module 51, the voltage digital input signal of the control module 51 is collected by the Hall sensor 53 in real time at the voltage value at the common node, and then the analog signal collected by the Hall sensor 53 is converted into a voltage digital signal by the AD conversion module 52, and the control Module 51 sends the grid-connected switching instruction according to the result of its calculation, and it is characterized in that control module 51 includes grid voltage, frequency calculation module 511 and anti-islanding operation detection and control module 512, and grid voltage, frequency calculation module 511 is used for collecting The voltage digital signal at the common node is processed to obtain information on the voltage amplitude and voltage frequency at the common node. The grid voltage and anti-islanding operation detection and control module 512 includes a frequency monitoring module 5123, a frequency change trend detection module ...

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Abstract

A detached island effect test method and a device based on active frequency deviation relate to a test method and a device to test distributive new energy grid integration power supply, in particular to a detached island effect test method and a device based on active frequency deviation. Regarding the utility model, 25 cyclic waves form a major cycle. Chopped wave rate cf of the first 15 cyclic waves is 0, and variance trend of the frequency is tested. Under the circumstance that frequency tends to rise, frequency disturbance with the chopped wave rate of cf is added in the grid frequency in the last ten cyclic waves, and initial value cfmax of the chopped wave rate cf is positive. Under the circumstance that the frequency tends to reduce, frequency disturbance with the chopped wave rate of cf is added in the grid frequency in the last ten cyclic waves, and initial value cfmin of the chopped wave rate cf is negative. By adopting the invention, not only the operation probability of the detached island tested is improved; but also testing time is reduced, and current harmonics injected into the grid is reduced.

Description

technical field [0001] The invention relates to a measurement and control method and device for distributed new energy grid-connected power supply, in particular to an islanding effect detection method and device based on active frequency offset. Background technique [0002] Distributed power generation systems composed of new energy sources are attracting more and more attention, especially wind power and solar grid-connected power generation. This is because: (1) The demand for electricity is increasing day by day, and non-renewable energy sources such as coal and oil are becoming exhausted, and it is imminent to seek alternative energy sources; (2) The environmental pollution caused by traditional centralized and large-scale fuel power generation has seriously affected society. For production and life, green new energy can help relieve environmental pressure; (3) Due to the wide distribution and low density of wind power, photovoltaic power generation and other new energ...

Claims

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Application Information

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IPC IPC(8): H02H7/26H02H7/28
Inventor 郑建勇梅军张先飞袁玲盛立健于明辉蒋立
Owner JIANGSU NARI TURBOSTAR ELECTRIC
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