一种优化的光伏全局最大功率点追踪方法

An optimized photovoltaic global maximum power point tracking method

当前的光伏最大功率点追踪技术存在以下不足:在局部阴影工况下,易陷入局部功率峰值;在负载波动时,系统容易出现振荡甚至失稳。针对上述问题,提出一种自适应的光伏全局最大功率点追踪设计方案。该方案将光伏输出端电压-功率扫描电路与Zeta斩波电路有机结合,通过单开关管的简单电路拓扑,既可实现光伏输出端电压−功率特性快速扫描,定位全局最大功率点位置,又能根据后级电路需要,实现升降压斩波直流调节。在光照等输入或负载发生突变后,所述系统均能进行开关管占空比自适应调整,确保稳定工作在全局最大功率点附近,避免出现大幅振荡与失稳。经过PSCAD-EMTCD仿真与样机实验验证,结果表明该方案能在包括局部阴影等各种复杂工况下自适应地快速追踪与锁定当前光伏全局最大功率点。

Current photovoltaic(PV)maximum power point tracking(MPPT)technology has the following shortcomings:it is easy for the system to fall into a local power peak under the working condition of partial shadow;it is easy for the system to oscillate and even be unstable when the load fluctuates.In order to solve these problems,an adaptive design scheme of PV global MPPT technology is proposed.The scheme combines a PV output voltage scanning circuit and a Zeta chopper circuit organically.Through the simple circuit topology of single switch tube,not only can the voltage power characteristic of photovoltaic output terminal be quickly scanned and the position of global maximum power point can be located,but also,according to the needs of the post-circuit,the DC regulation of voltage buck or boost chopping can be realized.After a sudden change of irradiance or load,the system can adjust the duty cycle of the switch tube adaptively to ensure stable operation near the global maximum power point and avoid large oscillation and instability.Through PSCAD-EMTCD simulation and a prototype test,the results show that the scheme can track and lock the current PV global maximum power point adaptively and quickly under various complex conditions including partial shadow.