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Determining method and system of conversion efficiency of group series type photovoltaic inverter

A photovoltaic inverter and conversion efficiency technology, which is applied to instruments, measuring electric power, and measuring electric variables, etc., can solve the problem of unequal power values ​​between the DC side and the AC side of photovoltaic inverters, and the efficiency evaluation of string photovoltaic inverters Inaccurate and other problems, to achieve the effect of improving the accuracy of efficiency evaluation, solving the problem of unequal power values, and filling vacancies

Pending Publication Date: 2019-07-09
CHINA ELECTRIC POWER RES INST +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problem in the prior art that the power values ​​of the DC side and the AC side of the photovoltaic inverter are not equal, resulting in inaccurate evaluation of the efficiency of the string photovoltaic inverter, the present invention provides a string photovoltaic inverter. Method and system for determining conversion efficiency of photovoltaic inverter

Method used

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  • Determining method and system of conversion efficiency of group series type photovoltaic inverter
  • Determining method and system of conversion efficiency of group series type photovoltaic inverter
  • Determining method and system of conversion efficiency of group series type photovoltaic inverter

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Embodiment 1

[0064] figure 1 It is a flow chart of the method for determining the conversion efficiency of the string photovoltaic inverter of the present invention, as shown in the figure:

[0065] S1: Fit all the obtained DC side power and AC side power based on the corresponding time to obtain a fitting curve.

[0066] Analyze the topological structure of the string photovoltaic inverter, determine the number of MPPT modules on the DC side, the voltage and current range of the DC side, and monitor the total input current and input voltage of each MPPT module of the inverter;

[0067] In a photovoltaic system, photovoltaic modules are connected in series to form a photovoltaic string, and 2 to 4 photovoltaic strings are connected in parallel to the string inverter MPPT module for conditioning, confluence, and inversion. Such as figure 2 In the specific operation flow chart shown, according to the number of PV modules connected in series, the open circuit voltage of the inverter can be...

Embodiment 2

[0089] Based on the same inventive concept, the present invention also provides a system for determining the conversion efficiency of a string photovoltaic inverter, including:

[0090] Fitting curve formulation module: based on the corresponding time, all the obtained DC side power and AC side power are fitted to obtain a fitting curve;

[0091] Power value acquisition module: based on the rated power of the string photovoltaic inverter, select the AC side power value; and based on the AC side power value, calculate the DC side power value in combination with the fitting curve;

[0092] Efficiency calculation module: based on the AC-side power value and the DC-side power value, obtain the AC-DC conversion efficiency of the string photovoltaic inverter.

[0093] The fitting curve formulation module includes:

[0094] The first data set acquisition submodule: collect the DC side power and the AC side power according to the set frequency, and store the DC side power and the AC ...

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Abstract

The invention relates to a determining method of the conversion efficiency of a group series type photovoltaic inverter. The determining method of the conversion efficiency of the group series type photovoltaic inverter comprises the steps that all direct current side power and alternating current side power obtained at a corresponding time are fitted to obtain a fitting curve; an alternating current side power value is selected based on the rated power of the group series type photovoltaic inverter; a direct current side power value is calculated based on the alternating current side power value, and the fitting curve is combined; and based on the alternating current side power value and the direct current side power value, the alternating and direct current conversion efficiency of the group series type photovoltaic inverter is obtained. According to the scheme, quadratic multinomial is adopted to fit the alternating and direct current side power of the group series type photovoltaicinverter, then corresponding power-efficiency points are found on the fitting curve, the problem that the power value of direct current side and alternating current side of the photovoltaic inverteris not equal is solved, the accuracy of efficiency evaluation is improved, and the problem that a vacancy in outdoor operation analysis and evaluation methods of the group series type photovoltaic inverter is filled is solved.

Description

technical field [0001] The invention relates to the field of photovoltaic inverter efficiency testing, in particular to a method and system for determining conversion efficiency of a string photovoltaic inverter. Background technique [0002] The advantage of the string inverter is that it is not affected by module differences between strings and shadow shading, reduces the mismatch between the optimal operating point of the photovoltaic cell module and the inverter, and maximizes the power generation. [0003] In the string photovoltaic inverter, in order to effectively deal with the inconsistency between the strings and the influence of shadow shading, there is usually no external confluence on the DC side, and a multi-channel maximum power point tracking module (Maximum Power Point Tracking for short) is used inside the inverter. MPPT), each MPPT module can be connected to 2 to 4 strings of photovoltaic strings, after being adjusted by the MPPT module, it can be inverted....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R21/00G01R31/00G06F17/50
CPCG01R31/00G01R21/00G06F30/20Y02E10/56
Inventor 董颖华李红涛张军军陈梅丁明昌
Owner CHINA ELECTRIC POWER RES INST
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