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通过对光伏发电最大功率点跟踪系统的研究,提出了PSO与电导增量法的双级最大功率跟踪(MPPT)控制算法。该算法能很好地解决传统电导增量法在采用较大跟踪步长时跟踪精度差,采用较小跟踪步长时跟踪速度慢,动态跟踪过程中功率震荡大的问题。所提出的算法包含最优占空比预测和最大功率点跟踪两个阶段。最优占空比预测阶段采用改进的PSO算法搜索最大功率点附近的工作电流和工作电压,然后根据搜索到的电压和电流计算最大功率点附近的最优占空比,该阶段能解决传统的电导增量法在采用较小步长时存在的跟踪速度慢、功率震荡大等问题;在最大功率点跟踪阶段接收上一阶段所搜索到的最优占空比,当电导增量法所产生的占空比接近最优占空比时,采用电导增量法进行控制,否则采用上一环节的最优占空比进行控制。仿真实验结果表明,PSO与电导增量法的双级MPPT控制算法跟踪速度快,跟踪精度高,功率震荡小,能很好地实现最大功率点跟踪。
Based on the research of maximum power point tracking system for photovoltaic power generation, a two-stage maximum power tracking (MPPT) control algorithm of PSO and conductance incremental method is proposed. This algorithm can well solve the problem of the traditional tracking incremental method has poor tracking accuracy when using larger tracking steps, slow tracking speed when using smaller tracking steps and large power turbulence during dynamic tracking. The proposed algorithm contains two stages of optimal duty cycle prediction and maximum power point tracking. Optimized Duty Cycle Prediction Phase The improved PSO algorithm is used to search for the operating current and the operating voltage near the maximum power point and then calculate the optimal duty cycle near the maximum power point based on the searched voltage and current, The incremental tracking method has the disadvantages of slow tracking speed and large power turbulence when using smaller steps, and receives the optimal duty cycle found in the previous stage at the maximum power point tracking stage. When the incremental conductance method is used, When the duty cycle is close to the optimal duty cycle, the conductance incremental method is used for control, otherwise, the optimal duty cycle of the previous cycle is used for control. The simulation results show that the two-stage MPPT algorithm with PSO and conductance incremental method has the advantages of fast tracking speed, high tracking accuracy and small power turbulence, and can achieve maximum power point tracking well.