【作者】 庞志超；

【导师】 程泽；

【作者基本信息】 天津大学 ， 控制理论与控制工程， 2010， 硕士

【摘要】 由于光伏发电系统的结构及其所处环境十分复杂,局部阴影或光照不均造成的阵列失配现象,使P-U特性由单峰值曲线变为多峰值曲线,不仅使光伏阵列的输出功率降低,其热斑效应还会造成安全和可靠性问题。目前,解决局部阴影影响的方法有两种:一是改变光伏阵列发电系统的结构,把集中式系统转变为多串式系统,但是这种办法会造成系统中变换器、控制器的数量大大增加,使整个系统的结构变复杂、提高成本、降低了可靠性。其二是在集中式光伏阵列发电系统中,应用全局峰值判定的最大功率点跟踪算法,但这种算法复杂,对控制器计算速度和精度要求较高,不易在硬件中实现。为解决输出功率受局部遮荫影响的问题,本文提出了一种光伏阵列的局部重构方法,通过改变光伏阵列的连接方式,用没被遮荫的光伏组件去补偿被遮荫的组件,改善了局部阴影下光伏阵列的输出特性,同时也避免了复杂的优化算法。为提高补偿的效率,本文首次将遮荫度模型的概念运用到光伏阵列模糊控制重构算法中。根据电池组各子模块遮荫度的不同,用专家系统的经验知识归纳总结模糊规则,经过模糊推理得出所需补偿电池组件的数目,用开关矩阵进行算法的实现,达到了降低光伏阵列的输出功率损耗的目的。搭建了光伏电池重构系统的硬件电路,在室外不同局部阴影条件下进行了实验。实验结果表明,光伏阵列经过重构后,被遮荫子模块的电压和输出电流值基本恢复到被遮荫前的水平。当阴影条件发生改变时,光伏阵列会再次重构,说明其对于环境的变化有着较好的响应能力。更多还原

【Abstract】 As the complicated structure of the PV generation systems and variety of application environments, the mismatch and hot spot phenomena caused by partial shading or non-uniform illumination not only heavily affect the output characteristics of photovoltaic arrays, but also create safety and reliability problems. The P-U curve of PV arrays will have the characteristics of multi-summit under partial shading, not only a serious decline in global peak power, and the local peak power also caused a great disturbance. At present, change the structure of PV generation systems into multi-string systems, but this approach cause lower reliability, the structure of the whole system change complex, increases the cost. Second, the application of global peaks for MPPT algorithm in the centralized PV generation systems, but it is complex to implement in hardware and the controller needs high speed and high precision.The output power of PV arrays is mainly affected by the irradiance. This paper proposes a reconfiguration method. PV arrays change the interconnection in order to change the distribution of the shadow, thus improving the output characteristics of PV arrays, to reduce the impact on the irradiance under partial shading, to reduce the decline in global peak power.For local reconfiguration method in PV arrays, this paper uses shading degree model to represent the size of decline in the irradiance of each submodule. TCT PV array is divided into a fixed solar array and an adaptive bank, and proposes the shading degree model-based fuzzy control reconfiguration algorithm. According to the shading degree of the submodules, the expert system summarizes the fuzzy rules. The number of modules to compensate is determined by the fuzzy inference. Using a switching matrix to change the connection of the adaptive bank and the fixed part of a PV array, the loss of the output power is reduced.In order to verify the validity of algorithm, the hardware circuit of the control system with partial shading condition is constructed. The experimental results show when the partial shade phenomenon occurs, the system can quickly respond to the changes of external environments.更多还原