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A method for detecting the pid decay of a string

A detection method and string technology, applied in the monitoring of photovoltaic systems, electrical components, photovoltaic modules, etc., can solve the problems of difficult to target components, complex EL testing, and easy misjudgment, so as to improve accuracy, facilitate calculation, Avoid Poor Directional Effects

Active Publication Date: 2020-03-31
CHINA HUADIAN ENG +1
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Problems solved by technology

[0003] The technical problem to be solved by the present invention is to overcome the defects in the prior art that when judging the PID attenuation of the strings of photovoltaic power plants, the diagnostic means are mainly aimed at the components, which are difficult to target the strings, and mainly rely on EL testing, but the EL testing is complicated and easy to misjudge. A method for detecting the PID decay of a string with low misjudgment, easy operation, simple calculation and high accuracy

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  • A method for detecting the pid decay of a string
  • A method for detecting the pid decay of a string
  • A method for detecting the pid decay of a string

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Embodiment 1

[0027] refer to figure 1 , the present embodiment judges whether there is PID attenuation in the following manner:

[0028] S1: The inverter starts the IV scan of the sub-array level under an irradiation condition, and collects the open-circuit voltage of each string in the sub-array and the component temperature of the solar cell module, where the sub-array includes multiple strings connected in series array, the radiation intensity of the sub-array is 100W / m 2 the following;

[0029] S2: For each string, calibrate the actually measured open-circuit voltage of the string by using the open voltage temperature coefficient of the component and the measured component temperature to obtain the calibrated open-circuit voltage;

[0030] S3: For each string, calculate the theoretical open circuit voltage of the string without PID attenuation under the irradiation condition according to the diode model;

[0031] S4: Calculate the ratio of the calibrated open circuit voltage to the ...

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Abstract

The invention discloses a method for PID (potential introduced degradation)of a string The method comprises that: an inverter starts sub-array level IV scanning under a radiation condition and collects open-circuit voltage and assembly temperature of a solar battery set of each string in the sub-array; for each string, a assembly open-voltage temperature coefficient and practically-measured assembly temperature are utilized to calibrate practically-measured open-circuit voltage of the string in order to obtain calibrated open circuit voltage; theoretic open-circuit voltage of a string having no PID under the radiation condition is calculated according to a diode model; a ratio of the calibrated open-circuit voltage of each string to the theoretic open circuit voltage is calculated; comparison is made on the ratio of each string in the sub-array and the first threshold value to obtain a quantity of strings, the ratios of which are smaller than the first threshold value; if the quantity is greater than a second threshold, the sub-array has PID . The method for detecting the PID string is low in misjudgment, easy to operation easy to calculation and high in accuracy.

Description

technical field [0001] The invention relates to a method for detecting PID attenuation, in particular to a method for detecting PID attenuation of a string of a photovoltaic power station. Background technique [0002] PID attenuation (Potential Induced Degradation, potential-induced attenuation) is a common attenuation type of components in high-temperature and high-humidity environments, which has a great impact on the power generation of power stations. However, the current diagnostic technology has the following problems: 1. Component diagnosis cannot be well applied to group string diagnosis; current diagnosis methods mainly rely on EL test (electroluminescence test) or group string IV curve (current-voltage curve); 2. However, EL test has the problem of complicated testing , while the string IV test mainly relies on judging that the string fill factor FF is abnormally low, but many other factors will affect the string FF, and it is easy to misjudgment; 3. The method of...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02S50/10
CPCH02S50/10Y02E10/50
Inventor 张廷军高峰李艳红
Owner CHINA HUADIAN ENG
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