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Photovoltaic grid-connected control method and photovoltaic grid-connected system

A control method and photovoltaic technology, applied in the direction of single-net parallel feeding arrangement, etc., can solve the problems of wrong judgment signal, reduction of electrolytic capacitor capacity, large DC current ripple, etc.

Active Publication Date: 2018-06-12
SUNGROW POWER SUPPLY CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The DC bus capacitors generally use electrolytic capacitors. When the temperature is very low, the capacity of the electrolytic capacitors will be greatly reduced. In this way, when one DC-DC converter works in the first mode, the other DC-DC converter works in the second mode. , the DC current ripple of the channel working in the second mode will be very large, which is prone to wrong judgment signals

Method used

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  • Photovoltaic grid-connected control method and photovoltaic grid-connected system

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Embodiment 1

[0073] see image 3 , which is a flow chart of Embodiment 1 of the photovoltaic grid-connected control method provided by the present invention.

[0074] The photovoltaic grid-connected control method provided in this embodiment is applied to a photovoltaic grid-connected system, and includes the following steps:

[0075] S301: Detect the internal ambient temperature T of the power generation device in the photovoltaic grid-connected system;

[0076] Wherein, the power generating device includes: the first DC-DC converter, the second DC-DC converter, an inverter and a DC bus;

[0077] It should be noted that all devices in the power generation device are located inside the same housing, and the detected temperature is the ambient temperature in the housing.

[0078] It should be noted that the DC bus is generally a series-parallel connection of multiple capacitors, figure 1 Only one capacitor is taken as an example for illustration. Because the capacity and withstand volta...

Embodiment 2

[0098] see Figure 4 , which is a flow chart of Embodiment 2 of the photovoltaic grid-connected control method provided by the present invention.

[0099] The difference between this embodiment and method embodiment 1 is that S405 is added;

[0100] Wherein S401-S404 are respectively the same as S301-S304 in the method embodiment 1, and will not be repeated here.

[0101] In S402, if it is determined that the internal ambient temperature of the power generation device in the photovoltaic grid-connected system is not less than the temperature preset value Tset, that is, T is greater than or equal to Tset, then S405 is executed. That is, if the internal ambient temperature of the power generation device is greater than or equal to the temperature preset value, the two converters are controlled according to the normal logic, and S405 is the normal logic.

[0102] In S403, if both the first DC-DC converter and the second DC-DC converter work in the first mode, or both the first ...

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Abstract

A photovoltaic grid connection control method and a photovoltaic grid connection system, comprising: judging whether an internal environment temperature of a power generation device in the photovoltaic grid connection system is less than a preset temperature value (S302), and when judging that one of a first DC-DC converter (100a) and a second DC-DC converter (100b) operates in a first mode and the other operates in a second mode (S303), controlling the two converters to forcibly operate in the first mode (S304). The power generation device comprises: the first DC-DC converter (100a), the second DC-DC converter (100b), an inverter (200) and a DC bus; the output end of the inverter (200) is connected with a power grid; the input end of the first DC-DC converter (100a) is connected with a first photovoltaic module device (PV1), the input end of the second DC-DC converter (100b) is connected with a second photovoltaic module device (PV2); the output ends of the two converters are both connected with the input end of the inverter (200) through the DC bus; the first mode is that the DC-DC converters are booster circuits; and the second mode is that the DC-DC converters are not boosted by a bypass. In this way, the occurrence of relatively large DC current ripples on the path operating in the second mode can be avoided, and the erroneous fault alarm is reduced.

Description

technical field [0001] The invention relates to the technical field of photovoltaic power generation, in particular to a photovoltaic grid-connected control method and a photovoltaic grid-connected system. Background technique [0002] With the shortage of energy in the world, many regions now use solar power to generate electricity, also known as photovoltaic power generation. [0003] In a solar power system, a photovoltaic module device converts light energy into electricity. Since the electric energy output by the photovoltaic module device is direct current, it is necessary to use an inverter to invert the direct current into alternating current and feed it back to the grid. This process is called grid connection. [0004] In order to realize that the inverter can work under a wider input voltage, a DC-DC (DC-DC) converter is generally added to the input end of the inverter to boost the voltage, that is, after the DC power output by the photovoltaic module device is bo...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
CPCH02J3/38
Inventor 耿后来徐清清邢军杨本和李浩源梅晓东
Owner SUNGROW POWER SUPPLY CO LTD