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Islanding detection method of grid-connected inverter

A technology of island detection and inverter, which is applied in the direction of instruments, measuring electronics, measuring devices, etc., can solve the problems of slow island detection response and difficult detection of high quality factors, etc., and achieve the effect of fast response

Active Publication Date: 2012-12-19
JIANGSU EVER SOLAR NEW ENERGY CO LTD
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Problems solved by technology

[0010] The present invention provides an islanding detection method for grid-connected inverters, which solves the problems of slow islanding detection response and difficult detection of high quality factors

Method used

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Embodiment Construction

[0015] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, so as to define the protection scope of the present invention more clearly.

[0016] as attached figure 2 As shown, an islanding detection method for a grid-connected inverter, in the first voltage loop cycle, samples the three-phase voltage, and takes out the reactive component Qs after vector transformation through PARK; adjusts the reactive component Qs through PI After the proportional integration of the controller, the PI output value Out and the real-time disturbance δ are obtained. , where K is the amplification ratio coefficient, Out is the PI output value, and Cf is a constant; compare the real-time disturbance δ with δmax and δmin,

[0017] When δ is larger than δmax or δ is smaller than δmin, it is ju...

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Abstract

The invention discloses an islanding detection method of a grid-connected inverter. The islanding detection method comprises the following steps of: sampling three-phase voltage in a voltage loop cycle period, performing PARK vector change and then taking a reactive component out; performing proportion-integration (PI) on the reactive component through a PI regulator to obtain a PI output value and real-time disturbance quantity delta; comparing the delta with delta max and delta min; judging that islanding occurs when the delta is greater than the delta max or less than the delta min; judging that the islanding does not occur when the delta is positioned between the delta min and the delta max; performing Summa integration on Out to obtain real-time phase angle theta of sampled voltage and superposing with the delta to obtain a reference phase angle theta I and performing SVPWM (Space Vector Pulse Width Modulation) on the theta I to form PWM (Pulse Width Modulation) wave when the delta is positioned between the delta min and the delta max; and performing feedback regulation on the three-phase voltage through the PWM wave in a current loop cycle period, performing feedback increase on the delta after a plurality of control periods and judging that the islanding occurs when the delta is greater than the delta max or less than the delta min.

Description

technical field [0001] The invention relates to an islanding detection method of a grid-connected inverter. Background technique [0002] There are generally two islanding detection methods for traditional grid-connected inverters, namely passive islanding detection and active frequency drift (AFD). [0003] The passive island detection method detects the voltage and frequency output by the inverter. When the island occurs and the load impedance does not match, the output voltage and frequency will deviate. When the offset reaches the protection point, the inverter protection will be triggered. This is used to detect the occurrence of islanding. With this method, because it is passive, when the output power of the inverter matches the load power, the output voltage and frequency have only a small change or remain unchanged, and the protection point cannot be reached, and the island cannot be detected at this time , there is a large blind spot. [0004] Active frequency dr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00
Inventor 王晓阳孙耀杰
Owner JIANGSU EVER SOLAR NEW ENERGY CO LTD
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