Photovoltaic (PV) system performance under cold and polluted conditions

太阳能现在被认为是最可靠和最有前途的可再生能源之一。利用光伏（PV）系统将太阳能转化为电能的效率因大气条件（如冰、雪和污染）而有很大差异。事实上，太阳能电池板上的冰、雪和污染沉积物会降低它们的性能，甚至阻止它们吸收太阳辐射。本研究计划的总体目标是从根本上调查这些条件对加拿大光伏系统能源效率的影响。实验研究了当冰、雪和污染层不均匀覆盖光伏板表面时，由于部分遮阳现象而导致的光伏系统能量降低。由于缺乏预测光伏系统在这种情况下的电气性能的数学模型，因此本研究旨在开发可靠的模型来分析光伏系统集成到电力系统中的行为。PV系统将通过从相关的物理现象中提取数学方程来建模。由于局部遮阳现象，光伏系统会经历几个局部最大功率点（MPP）。因此，本文将提出一种最大功率点跟踪器（MPPT），通过跟踪与MPP对应的光伏工作电压，从光伏阵列中提取最大功率。此外，还将提出一种控制系统来调节光伏发电系统并网时的电压和频率。基于实验室工作和三维有限元法（FEM）模拟的结果，将提供几种可能的解决方案来优化光伏发电的能量。特别是，这项工作将为根据冰雪和污染的严重程度选择光伏阵列的优化尺寸和倾斜角度提供有价值的信息。所生成的MPPT模型将为在寒冷和污染地区从光伏系统中提取最大功率提供有效的方法。拟议的控制系统将提供光伏系统与电网的平稳整合，从光伏系统高效地提取能量，以及在寒冷和污染环境中对电网进行频率/电压调节。由于加拿大特殊的气候条件以及光伏系统的快速发展，这项工作将吸引光伏社区，研究人员和从业人员的相当大的兴趣。

Solar energy is now considered to be one of the most reliable and promising sources of renewable energy. Efficiency of conversion of solar energy into electricity by means of photovoltaic (PV) systems varies considerably depending on atmospheric conditions such as ice, snow and pollution. In fact, ice, snow and pollution deposits on solar panels can reduce their performance or even stop them from absorbing solar radiation. The general objective of this research program is to investigate fundamentally the effect of such conditions on the energy efficiency of the PV systems in Canada. The energy reduction of the PV systems due to the partial shading phenomenon when ice, snow and pollution layers cover the PV panel surface non-uniformly will be investigated experimentally. The lack of mathematical models for forecasting the electrical performance of PV systems under such conditions has motivated the present study, which aims at developing reliable models to analyze behavior of the PV system integrated into the power system. The PV system will be modeled through extracting mathematical equations from associated physical phenomena. Due to the partial shading phenomenon, the PV system experiences several local Maximum Power Points (MPP). Hence, a Maximum Power Point Tracker (MPPT) to extract maximum power from the PV array through tracing the PV operating voltage corresponding to the MPP will be proposed. Moreover, a control system will be presented to regulate the voltage and frequency when the PV system energizes the power grid.Based on the results obtained from laboratory work and simulation using the 3D Finite Element Method (FEM), several possible solutions to optimize the energy generated by the PV will be offered. In particular, this work will provide valuable information for the selection of the optimized dimension and tilt angle of the PV arrays with respect to the severity of ice, snow and pollution. The generated MPPT model will offer effective methods to extract the maximum power from the PV systems in cold and polluted regions. The proposed control system will provide smooth integration of the PV system into the power grid, efficient energy extraction from the PV system as well as frequency/voltage regulation of the power grid in cold and polluted environments. Due to particular climate conditions in Canada as well as the rapid growth of photovoltaic systems, this work will attract considerable interest of the PV community, both researchers and practitioners.