【作者】 翟载腾；

【导师】 程晓舫；

【作者基本信息】 中国科学技术大学 ， 工程热物理， 2008， 博士

【摘要】 由于太阳电池的特殊性质,光伏发电系统的研究如果采用真实的光伏阵列,会产生实验成本高、需要大量空旷场地和对光照、自然气候依赖性强等一系列的问题。若能够准确预测太阳电池在不同光照和温度下的输出特性,以及当太阳电池串、并联构成光伏阵列后新的输出特性,并由此分析其最大的输出功率,就能够节约大量实验成本。首先,提出了一种快速、精确的太阳电池(组件)模型参数的确定方法:基于太阳电池(组件)一般电流模型,通过对电流方程的一阶求导和在短路点处的合理简化,经过数学变换将超越方程转换为代数方程,结合电流方程在最大功率点处的极值表述,构造出一个封闭的代数方程组,可以较为准确地求解出五个参数值,再用非线性拟合的方法对解析解进行优化,从而一方面提高了太阳电池(组件)一般电流方程模型参数的求解精度,另一方面也大大提高了解的稳定性。其次,预测太阳电池(组件)的性能:太阳电池(组件)的制造厂商仅提供标准测试条件下的一条I-V曲线,而实际使用时组件的工作状态通常并不在测试条件上,因此预测组件在各种工况下的输出特性就十分必要。本文第三章提出仅依靠一条标准测试条件下组件的I-V特性曲线就可准确预测组件在不同工况下输出特性的方法。该方法先由一条标准测试条件下的I-V曲线提取出太阳电池模型参数,再结合模型参数随光照和温度的变化关系式,给出了不同光照和温度下组件性能特性的预测;并对模型参数就最大输出功率的影响做出了一些有意义的探讨:指出了标准测试条件下光生电流和二极管影响因子对组件P-T特性和P-S特性有着较大的影响,且均是值越大输出的最大功率越大;对太阳电池串、并联原则提出了有益的补充,在串联时各单体太阳电池除最大功率点电流相等外,最好各电池在标准测试条件下光生电流也相等;并联时除最大功率点电压相等外,最好各电池在标准测试条件下二极管影响因子也相等。在分析光伏阵列输出特性时,由于在串联连接时需要单独地研究电压,并联连接时需要单独地分析电流,而I-V方程的隐式表述无法将电流和电压分开,因而给分析组件串、并联连接特性带来了困难。运用Lambert W函数得到电流和电压方程的显式表述,分别给出了各组件模型参数相等和不等时光伏阵列的模型参数与构成阵列的组件模型参数之间的关系,从而可以对阵列的输出特性进行预测;对于安装了旁路二极管和隔离二极管的光伏阵列,运用分段函数的理论给出了预测其输出特性的方程,论证了光照不均和温度不均对阵列输出特性的影响:指出了光照不均匀对串联支路影响很大,对并联支路则影响不大;而温度不均匀对串联支路影响不大,但对并联支路则影响较大。针对Mallab仿真环境,以太阳电池五参数模型为基础,结合模型参数随光照和温度的变化关系式,现代电力电子技术,建立了光伏阵列模拟器的仿真模型。该模型完全模拟了太阳电池主电路结构,可分别对任意环境温度、太阳辐射强度下光伏阵列和带有二极管的光伏阵列的输出特性进行仿真实验,其结果对建立可以完全模拟任意工况下光伏阵列输出特性曲线的仿真模型具有很大的理论指导意义。更多还原

【Abstract】 Because of the special properties of the solar cell, if the research of the solar power systems adopts true photovoltaic array, will produce a series of questions such as the high cost of experiment , needing a large number of spacious field, strong dependence on insolation level and natural climate. If the solar cell output characteristics can be predicted at different insolation level and ambient temperature accurately, as well as the array that the cells are connected in parallel and series output characteristics can be predicted, thus the maximum power can be analysed. A large number of experiment cost may be saved.First of all, a fast, accurate method for extracting the solar cell (module) model parameters is put forward. Based on solar cell current model, the current equation is transformed from the complicated transcendental equation into the simple algebraic equation by differential coefficient to current equation and simplifing at short circuit, combining with the description at the maximum power point to set up a close algebraic equation group for solving the series resistance, the shunt resistance, the photo-generated current, the reverse saturation current density and the diode ideal factor, then educe analytic solutions of various model parameters. At last, using nonlinear fitting optimizes the analytic solutions. This method on the one hand improves the precision of extracting parameters , on the other hand greatly improves the stability.Next, predicting the solar cell (module) performance. The solar cell (module) manufacturers provide only an I-V curve under the standard test condition, but the solar cell (module) actually does not work at the standard testing condition. Thus, the prediction of the solar cell (module) output characteristics under various working conditions is very necessary. A method can accurately predict the module output characteristics under different working conditions which only needs a measured I-V curve under standard testing conditions is present in the third chapter. This method, firstly, extracts the solar module model parameters using an I-V curve under standard testing conditions. Secondly, together with the relationships of model parameters varying with illumination intensity and cell temperature, the prediction of solar module output characteristics under different work condition is made. Finally some significant phenomena of solar module characteristics impacting the maximum power is discussed. The results show that the photo-generated current and the diode ideal factor at the standard testing condition have greater influence on the module P-T and P-S characteristics. Some useful supplements are put forward on the principles of series and parallel. The photo-generated current of individual cell in series at the standard testing condition is equal besides the current of maximum power, the diode ideal factor of individual cell in parallel at the standard testing condition is equal besides the voltage of maximum power.When analysing the output characteristics of photovoltaic array, series connected module need study voltage separately and parallel connected module need study current separately. But the implicit I-V equation expression can not be used to study current and voltage separately, which make the analysis for characteristics of series and parallel connected module difficult. But the explicit expressions of current and voltage which based on the Lambert W function make analysing current and voltage separately possible. The relationships between the array parameters and the modules parameters respectively are showed for individual module parameters being identical and different, thus the output characteristics of array are predicted. For photovoltaic array with bypass diodes and block diodes, the output characteristics of array are accurately described by subsection function. Uneven illumination and temperature impacting the output characteristics of array is demonstrated.A simulation model for photovoltaic array simulator is developed under Matlab environment, based on solar cell five parameters model, together with the relationships of model parameters varying with illumination intensity and cell temperature ,and modern power electronic technology,The model fully simulates the main circuit structure of solar cell. The I-V characteristics of photovoltaic array without diode and with diode can be simulated at any corresponding insolation level, ambient temperature. The results have great theoretical significance for developing the simulation model that can completely simulate the output characteristics of array under different working conditions .更多还原