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Islet operation detecting method of photovoltaic parallel network generating system

A technology for grid-connected power generation and operation detection. It is applied in photovoltaic power generation, single-grid parallel feeding arrangement, electrical components, etc., and can solve problems such as frequency offset and interference.

Inactive Publication Date: 2008-09-03
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV +1
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  • Abstract
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  • Application Information

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Problems solved by technology

[0012] 3. Software and hardware costs;
But since the grid frequency is not always constant, set it to f grid0 will cause additional disturbance
In addition, the two-way frequency offset, the detection effect in multiple parallel PV systems needs to be further verified

Method used

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  • Islet operation detecting method of photovoltaic parallel network generating system
  • Islet operation detecting method of photovoltaic parallel network generating system
  • Islet operation detecting method of photovoltaic parallel network generating system

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Embodiment Construction

[0052] The present invention will be further described below in conjunction with the accompanying drawings.

[0053] The method of the invention is applicable to a digital grid-connected inverter control system, and the voltage zero-crossing detection hardware circuit and the like at the grid-connected port of the inverter can be easily realized by adding corresponding software programs. Its core technology is to use the double positive feedback active frequency offset method (AFDDPF) to realize the rapid detection of the island operation status.

[0054] Image 6 It is a schematic diagram of the system structure of an embodiment for realizing the method of the present invention. The system adopts a conventional grid-connected inverter with single-stage + power frequency transformer structure, and the control device adopts HD64F7047 chip, which undertakes all tasks, including island detection, grid-connected current command generation, output current waveform modulation, etc....

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Abstract

The invention provides an isolated island operation detection method of photovoltaic grid-connected generation system which includes: a control device detects voltage frequency of grid-connected point, judges voltage frequency of grid-connected point whether reaching frequency protection threshold, if yes, a start anti-isolated island protection signal is outputted; if not, frequency signal of grid-connected current instruction is calculated by using double positive feedback active frequency deflection method, and the frequency signal is outputted; the double positive feedback active frequency deflection method is that obtained grid-connected point voltage frequency deflection relative to average frequency is used as first positive feedback, and change trend of frequency deflection is used as second positive feedback, feedback magnification factor of first positive feedback is adjusted. The method realizes isolated island detection rapidly, simulation and experimental result, isolated island detection time is shorten in 0.10s, 0.13s, grid-connected current harmonic distortion THD are 2.06%, 2.97% respectively, and has advantage over traditional method in isolated island detection speed and reducing interference to power network.

Description

technical field [0001] The invention belongs to the technical field of photovoltaic power generation and photovoltaic grid-connected power generation, and specifically relates to a method for detecting island operation of a photovoltaic grid-connected power generation system. Background technique [0002] Energy has become a major issue of common concern to the international community. New energy such as solar energy has been paid more and more attention due to its renewable and clean characteristics, and grid-connected photovoltaic power generation is an important form of large-scale utilization of solar energy. Photovoltaic grid-connected power generation system (hereinafter referred to as PV system) converts the direct current generated by solar cells into alternating current with good waveform through the grid-connected inverter, and directly supplies power to the grid without the need for energy storage devices such as batteries. The construction of the system And maint...

Claims

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Application Information

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IPC IPC(8): H02H7/22H02J3/38
CPCY02E10/563Y02E10/56
Inventor 徐政丁强施洪峰
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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