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Photovoltaic string shutoff device and method and photovoltaic system

A photovoltaic group and string technology, applied in photovoltaic power generation, circuit devices, AC network circuits, etc., can solve problems such as insufficient arc extinguishing power, overheating, leakage and sparks

Active Publication Date: 2018-09-21
厦门科华恒盛电力能源有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The arc extinguishing capacity and rated on-load cut-off power of these switches are far from enough, so it is easy to cause overheating, leakage and sparks, and even burn down the entire photovoltaic power station in severe cases
At the same time, as the voltage level of the DC side of the photovoltaic system is gradually increased to 1500V, and the power level of the single unit increases, the inverter unit has stricter requirements on the withstand voltage level and breaking capacity of the DC side shutdown device, and the DC side shutdown device on the market may have design The defect caused the switch to be unable to be completely cut off, and even caused arcing, and the huge heat generated became a hidden danger of electrical fire in the photovoltaic system

Method used

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  • Photovoltaic string shutoff device and method and photovoltaic system
  • Photovoltaic string shutoff device and method and photovoltaic system

Examples

Experimental program
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Effect test

Embodiment 1

[0032] figure 1 A structural diagram of a device for shutting down a photovoltaic string provided by an embodiment of the present invention. Such as figure 1 As shown, the device includes a switching device 10 arranged on each photovoltaic string circuit, an acquisition device 11 for collecting operating signals of each photovoltaic string circuit, and a shutdown controller 13 connected to the acquisition device 11 and the MPPT unit 12 The shutdown controller 13 is used to trigger the MPPT unit 12 to enter the group string shutdown mode from the current maximum power tracking mode when the operation signal meets the preset shutdown condition, so that the MPPT unit 12 controls each photovoltaic string circuit to switch from the maximum power The corresponding voltage is increased to the open circuit voltage, and the target switching device is controlled to be turned off when the open circuit voltage is reached.

[0033] The purpose of the present invention is to improve the r...

Embodiment 2

[0046] Such as figure 2 As shown, on the basis of the first embodiment, as a preferred implementation, it also includes a diode D arranged on each photovoltaic string loop, the anode of the diode D is connected to the photovoltaic string, and the cathode of the diode is connected to the MPPT unit 12 .

[0047] In this embodiment, the function of the diode is mainly for reverse isolation. Since the PV+ and PV- between different strings are converging in the MPPT unit, after a certain string is cut off, the high voltage at both ends of the contacts of the switching device remains There are certain potential safety hazards; the diode can prevent other strings or MPPT units from feeding back current to the string. By setting diodes, it is possible to effectively prevent the reverse current from causing damage to the photovoltaic strings. The parameters of the diodes need to be determined according to the actual parameters of the specific photovoltaic string circuit, which is not ...

Embodiment 3

[0049] In the above embodiments, the shutdown controller makes a logical judgment based on the operating signal of the photovoltaic string circuit, so as to control the MPPT unit to be in the maximum power tracking mode or the string shutdown mode. In the specific implementation, in addition to the abnormal operation signal causing the MPPT unit to enter the string shutdown mode (active shutdown mode), the shutdown controller is also used to trigger the MPPT unit to enter the string shutdown mode when receiving an external shutdown control command. shutdown mode (passive shutdown mode).

[0050] The active shutdown mode is mainly a protective shutdown action made by the string shutdown device in the event of overcurrent, leakage current, overvoltage, automatic load reduction of the inverter unit when the temperature is too high, arc fault and fire.

[0051] Figure 4 A flow chart corresponding to an active shutdown mode provided by an embodiment of the present invention. Suc...

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PUM

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Abstract

The invention discloses a photovoltaic string shutoff device. The photovoltaic string shutoff device comprises switch components, acquisition devices and a shutoff controller, wherein when the shutoffcontroller determines that running signals acquired by the acquisition devices meet a preset shutoff condition, an MPPT unit is triggered to enter a string shutoff mode from the current maximum powertracking mode, the voltage of each photovoltaic string is increased from the voltage corresponding to the maximum power to the open-circuit voltage, and when the open-circuit voltage is reached, theshutoff controller controls a target switch component on an abnormal loop to be disconnected. When the open-circuit voltage is reached, the current output by the photovoltaic string approaches zero, so that requirements on the switch components are low and reliable disconnection can be achieved; in addition, after the target switch component is disconnected, the input current, the voltage and thepower on the direct current side of an inverter unit are very small, so that phenomena of overheating, electrical leakage and the like are not easily caused and a direct current shutoff device can bereliably shut off. The invention further discloses a photovoltaic string shutoff method and a photovoltaic system. The photovoltaic string shutoff method and the photovoltaic system have former effects.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic string shutdown device, method and photovoltaic system. Background technique [0002] At present, photovoltaic systems are widely used, especially the promotion of distributed photovoltaic systems. Although the development of photovoltaic systems can promote better utilization of renewable energy, photovoltaic systems have also brought some problems in recent years. For example, photovoltaic fire accidents have gradually threatened residential buildings, commercial facilities, public facilities and their photovoltaic systems. safety. The photovoltaic system includes photovoltaic strings, MPPT units (MPPT, maximum power point tracking) connected to photovoltaic strings, inverter units, DC side shut-off devices and other components. Among them, the MPPT unit is mainly used to control the photovoltaic strings to work at the maximum power point....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCH02J3/385Y02E10/56
Inventor 赵尚程姚美齐
Owner 厦门科华恒盛电力能源有限公司