中文摘要：

光伏直流模块化结构能各自独立实现最大功率点跟踪（MPPT）,减少由于模块之间运行失配而导致的功率损失。但级联运行的方式常由于DC变流器的变换比率限制导致并不是所有太阳能模组都能运行在最佳功率位置。考虑光伏模组最佳工作电流（MPP电流）与短路电流之间的近似比例匹配,在电流步长足够精确以及模组参数I0和Rs在线辨识或有离线策略依据的情况下,实际运行功率裕度可由工作电流与最佳MPP电流之间的功率积分计算得出。所提出的光伏实际运行裕度定量评估方法,可用以解决失配场景下的级联结构2级控制（功率控制和电压控制）运行点优化问题。重点考察了一些典型失配场景,仿真结果也证实了功率裕度评估方法及工况运行矫正的有效性。

英文摘要：

PV/DC modular system realizes individual module MPPT（Maximum Power Point Tracking） to decrease the module mismatching losses.However,the conversion ratio limit of DC converter may cause the modules of cascaded configuration not all operating at the optimal levels.Therefore,based on the approximate proportion between optimal operating current（MPP current） and short-circuit current,the practical power margin can be reckoned from the integration between practical operating current and MPP current,as long as the current step is exact enough and the module parameters（I0 and Rs） are online measured or offline resorted.The proposed quantitative evaluation approach may be used to optimize the operating points of cascaded two-level controls（power and voltage controls） in mismatching conditions.Typical cases are investigated and simulative results show the validity of power margin evaluation and operating point correction.