基于最优初值电导增量控制的光伏系统最大功率跟踪策略

Maximum Power Point Tracking Strategy for Photovoltaic System Based on Optimal Initial Value of Incremental Conductance Control

本文首先在时变环境参数与任一运行电压、电流之间建立了一种非线性函数关系,从而将太阳能电池运行中的时变环境参数实时计算出来。其次,确定了时变环境参数与理论最大功率点电流的函数关系,在环境参数已知的情况下可快速计算最大功率点电流值。最后,考虑到实际工程中理论最大功率点与实际运行最大功率点存在偏差,提出以理论最大功率点电流作为电导增量法运行初值,在小步长电导增量法的作用下实现精确稳态跟踪的方法。实验验证了光照度计算是相对准确的,在光照度计算的基础上进行仿真,证明了该控制策略能够实时精确地跟踪最大功率点功率,即使在低辐照度条件下同样表现出良好的精确性及无振动性。

In this paper, a nonlinear function relationship is established between the time varying environmental parame- ters and any operation voltage or current at first, thus the time varying environmental parameters of the solar cell under operation can be calculated in real time. Then, the function relationship between the time varying environmental param- eters and the current at the theoretical maximum power point is determined, so the above current can be calculated rap- idly with the known environmental parameters. Finally, considering that there is difference between the theoretical maxi- mum power point and the actual maximum power point under operation in a practical project, it is suggested that the current at the theoretical maximum power point should be used as the initial value of the incremental conductance meth- od. In this way, an accurate steady-state tracking is realized by using the small-step incremental conductance method. Experimental results show that the illumination calculation is relatively accurate, and simulation results based on the il- lumination calculation show that the proposed control strategy can accurately track the power at the maximum power point with good accuracy and without oscillation even under low-irradiation conditions.