Convergence detecting method and system for convergence box and solar power station

Abstract

The invention provides a convergence detecting method and system for a convergence box. A zero value and mean value judging method is utilized for carrying out fault detecting, during zero value judgment, current values of adjacent input ends or similar input ends are utilized for verification, during mean value judgment, the number of solar battery pack strings actually connected to the input ends of the convergence box of the grade are taken into consideration for mean value judgment, and the fault judgment accuracy of the convergence box in a photovoltaic array is improved. The invention further provides a solar power station.

Description

technical field [0001] The invention relates to the field of solar power generation, in particular to a confluence detection method and system for a combiner box, and a solar power station. Background technique [0002] With the increasing shortage of energy, the development and utilization of renewable green energy has attracted more and more attention, especially the utilization of solar energy has been favored by the world. As a clean, safe, sustainable and reliable energy source, solar photovoltaic system is rapidly expanding its application in energy and industrial technology development. In recent years, the development and application of photovoltaic cells and large-area photovoltaic module devices as solar energy conversion media have attracted widespread attention. The wide application of solar panels represented by monocrystalline silicon, polycrystalline silicon, and amorphous silicon thin films in commercial and residential buildings and other facilities has sho...

AI Technical Summary

Problems solved by technology

[0006] Use whether the average value of the current value has a sudden change to judge whether a fault occurs, if n is the current value of the input terminal n of the combiner box, a is the number of input ends of the combiner box, that is, I ave The sum of the current values ​​of the input terminals of this combiner box is divided by the number of input terminals of this combiner box, without considering the difference in the number of upper-level combiner boxes or solar battery strings connected to each input terminal, resulting in the judgment result Inaccurate

For example, for a third-level combiner box, there are both input terminals directly connected to the solar battery strings and input terminals connected to the second-level combiner box, and the second-level combiner box also has both input terminals directly connected to the solar battery strings. When there is an input terminal connected to the first-level combiner box, when using the above-mentioned current average value judgment method to judge, it is obvious that the average value of the input current of the third-level combiner box will seriously deviate from the actual working situation, because the third-level combiner box The current value of the input terminal connected to the secondary combiner box should be much larger than the current value of the input terminal directly connected to the solar battery string, and it is easy to cause false alarms after taking the average value

Moreover, in the prior art, all input terminals of the combiner box are generally included in the calculation during calculation, and unused input terminals (empty input terminals) are not considered, which will further increase the deviation between the judgment result and the actual situation

[0007] 2. Fuse alarm method

[0009] The disadvantage of this method is: for the morning and evening of the day, affected by light or shadow, it is very likely that some solar cell strings still generate electricity but only the solar cell strings The current is small and some components are not generating electricity

[0010] It can be seen that the existing fuse alarm judgment logic will introduce daily false alarms

[0011]3. Current low value cross limit method

[0013] The disadvantage of this method is: for multi-level confluence monitoring, the current value of each input terminal in the combiner box may be the multi-string battery components connected to the previous multi-level combiner box sum of current

This kind of alarm signal due to changes in natural conditions will lead to a high false alarm rate

[0014]4. High current value over-limit method

However, first of all, this technical solution only takes into account the rate of change of one current, and does not take into account the current changes of the solar battery strings caused by the above-mentioned building shading and other conditions, and the fault false detection rate is still high; secondly, In the case of multi-level combiner boxes, this technical solution is only applicable to the current collection and detection between the output terminal of the last level combiner box and the inverter, but not for individual solar battery strings or upper level combiner boxes. The failure of the box is detected, so that the technician only knows that a failure has occurred, but does not know where the failure occurred

[0018] Regardless of any of the above detection methods, the current value or rate of change of a single input terminal or output terminal of the combiner box is measured in the time domain or frequency domain. The comparison of environmental factors cannot be ruled out, and the fault false alarm rate is high

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