独立光伏储能系统鲁棒稳定电流控制器参数设计

Design of Robust Current Controller Parameters for Stand-Alone Photovoltaic Energy Storage System

为提高独立光伏储能系统的可靠性,提出了恒流充电模式下光伏接口变换器的鲁棒PI控制器参数的设计准则和设计方法。针对采用前置电容式Boost变换器的独立光伏储能系统,建立了包含光伏电池动态模型的系统小信号模型,基于劳斯稳定判据分析了恒流充电模式下接口变换器的稳定工作条件。分析表明,光伏电池的动态输出电阻ro及静态工作点（占空比D）对系统稳定性存在影响。ro越小,占空比D越大,系统越难稳定,因此应在最小ro、最大占空比D的工况下设计输出电流控制器参数。基于该设计准则和方法所得到的PI控制器参数具有很好的鲁棒性,可以确保独立光伏储能系统在实际变参数条件下的稳定性。

To improve reliability of stand-alone photovoltaic（PV） energy storage system, design criteria and methods of robust PI controller for output current control are proposed. A boost converter with an input capacitor is taken as an example and its small signal model including dynamic equivalent circuit of solar cells is developed. Stable condition of the stand-alone PV energy storage system in constant current charging（CCC） mode is deduced with Routh stability criterion. It is indicated that the system stability is influenced by dynamic output resistance ro of solar cells and steady-state operating point（duty-cycle D） and worsens with decrease of ro and increase of D. Hence, the output current controller should be designed under the operation condition of minimum ro and maximum D. The controller parameters obtained with these criteria and methods can ensure that the stand-alone PV energy storage system operates stably within entire range of environmental factors（i.e. temperature and illumination） and load conditions.