单级式光伏并网逆变器的PR和MPPT集成控制策略

Integrated Control Strategy of PR and MPPT for Single-stage Photovoltaic Grid-connected Inverter

单级式光伏并网逆变器具有结构简单,成本低、效率高的优点,尤其适合于大容量光伏并网发电系统。针对单级式光伏并网逆变器,提出了一种结合PR和MPPT控制的集成控制策略,它具有功率外环和电流内环的结构,可以同时实现最大功率无差跟踪控制和单位功率因数并网控制。建立了α-β坐标系下的逆变器系统数学模型,给出了结合根轨迹和频率特性的PR控制器参数设计方法,并进行了参数设计。建立了10 kW单级式光伏并网发电系统的仿真模型,仿真结果表明,在模拟标准光强、云朵飘过及全天光照的条件下,PR和MPPT集成控制策略能够快速跟踪光照的变化,实现MPPT的无差跟踪控制及单位功率因数并网控制,具有良好的动静态性能。

The single-stage photovohaic grid-connected inverter has the merits of simple structure, low cost and high efficiency, and is especially suitable for large capacity systems of photovohaic power generation. An integrated control strategy for single-stage photovoltaic grid-connected inverter, which combined PR control with MPPT control with outer power loop and inner current loop, was put forward to achieve both zero error maximum power point tracking （MPPT） and unity-power factor control. Based on the mathematic model of the inverter system established under a-fl coordinate, the parameter design method of the PR controller, is given by combined the root locus and frequency characteristics, and its parameters have been designed. The simulation model of a 10 kW single-stage photovoltaic grid- connected power generation system was built, and the simulation results show that under the condition of standard illumination, illumination changes and whole day illumination, the integrated control strategy can fast track illumination changes, and achieve zero error maximum power point tracking and unity power factor control so that the system has achieved excellent dynamic and static performances.