A series-parallel mismatch loss rate test device and test method for a photovoltaic system

Abstract

The invention discloses a photovoltaic system series-parallel mismatch loss ratio test device and a test method thereof. The test device comprises a first IV curve test plate used for testing a whole string or string conflux, a plurality of second IV curve test plates used for testing a corresponding channel of each path of assemblies, series connection switching switches used for serial assemblies, parallel connection switching switches for parallel connection assemblies, test switching switches used for testing IV curves, an interface conversion plate, a PC, and a control panel. The test method additionally comprises testing once a whole IV curve based on a current test method, provides a reliable loss ratio result when the maximum power deviation of twice tests is less than a certain threshold, and substitutes a formula with the power average value of twice whole strings or stings after conflux for calculation, thereby obtaining more scientific and more reasonable measuring results.

Description

technical field [0001] The invention relates to the field of photovoltaic system performance detection, in particular to a series-parallel mismatch loss rate test device and a test method for a photovoltaic system. Background technique [0002] Photovoltaic systems are usually composed of photovoltaic modules, strings, combiner boxes, inverters and other equipment. Depending on the open circuit voltage of a single photovoltaic module and the input voltage range of a photovoltaic grid-connected inverter, multiple photovoltaic modules need to be connected in series to form a string, and multiple strings are connected in parallel through a combiner box and then connected to the inverter. Series-parallel mismatch losses in photovoltaic systems are caused by the interconnection of photovoltaic modules that do not have the same characteristics or experience different conditions causing problems to arise. For a photovoltaic system, the distance between each string is different, an...

AI Technical Summary

Problems solved by technology

[0005] Since there is no relevant test device for measuring the series and parallel loss rate of photovoltaic systems, many testing institutions do not measure this indicator

Even the measurement is only to use a portable solar cell IV tester to measure the I-V curve of the disconnected components or strings one by one. Not only the work intensity is high, but more importantly, due to a long test cycle, errors caused by irradiance or temperature changes Or even exceed the specified requirements; or use a high-power DC high-voltage switching relay plus multiple portable solar battery IV testers to test the split device at the same time, but the power of one string can reach 10kW (voltage 1000V, current 10A), or even more High, the required high-power DC high-voltage switching relay is very expensive, and the test results are not easily reproducible, so it is urgent to provide a more accurate automatic test device to solve the above problems

[0006] The detection methods given in the technical specifications only carry out the overall test IV curve test and the IV curve of each component or string. The random measurement error caused by the number of single test samples even exceeds the set judgment conditions, completely dependent on the constant The outdoor environment and high-cost high-precision data acquisition system make the test particularly difficult; in addition, the non-reproducibility of the test data of this indicator also increases the difficulty for the acceptance of the power station. Therefore, it is urgent to provide a more scientific test method to solve the above problems

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