光伏系统最大功率点追踪方法的改进

Improvement of maximum power point tracking for photovoltaic system

针对传统的最大功率点跟踪(MPPT)法、恒定电压法不能准确地跟踪最大功率点和登山法跟踪速度慢、误判断和输出电压不稳定等缺点,提出了定步长与变步长相结合的三点最小二乘MPPT方法。建立了光伏发电系统的数学模型,并进行了系统设计和实验,在不同的起始电压和初始步长的情况下,追踪光伏发电系统的最大输出功率。仿真结果证明,三点最小二乘MPPT能够准确追踪光伏发电系统的最大功率点,但跟踪速度受初始条件的影响。以TMS320F2812为控制芯片对光伏系统MPPT电路进行系统设计并进行试验,结果表明该系统输出电压稳定,与无MPPT相比,输出功率明显提高,系统效率提高约15%。

To improve traditional MPPT（Maximum Power Point Tracking） methods in accuracy,velocity, detection and stability,the three-point least square MPPT is offered,which combines fixed step with variable step. The photovoltaie system model is built up, and the TMS320F2812-based MPPT system is designed and the tests of MPPT with different initial voltages and steps are carried out,showing that the maximum power point is accurately tracked and the system output voltage is more stable,but the tracking speed is affected by the initial conditions. Compared with non-MPPT system,the output power is significantly enhanced and the system efficiency increased about 15%.