基于参考电流型光伏发电系统变功率输出控制策略

Variable power output control strategy for photovoltaic power generation system based on reference current mode

针对两级式光伏并网发电系统变功率输出技术的研究及应用现状,提出了一种新型的参考电流型变功率输出控制策略。通过光伏功率与指定功率的比较,实时改变光伏电流,可以实现最大功率跟踪和指定功率跟踪两种功率输出模式,并且在日照强度变化情况下能够快速有效地控制光伏功率的输出。所提控制策略对Boost变换器进行小信号建模,详细分析了不同功率下光伏阵列等效阻抗对前级系统稳定性的影响,并介绍了双模式功率输出的控制器设计。最后仿真和实验结果验证了所提控制策略的有效性。

According to the research and application status of variable power output control in two-stage grid-connected photovoltaic(PV) system, a novel variable power output control strategy based on reference current mode is proposed. By comparing the constant power with the PV power and changing the current of PV, this method is able to realize two PV power output modes, i.e. MPPT mode and constant power generation(CPG) tracing mode, and also can control the PV power output fast and effectively under different solar irradiation. A small signal model of Boost converter is built by using the proposed control strategy. It analyzes the impact of PV array equivalent impedance on pre-stage system stability under different power in detail and introduces the controller design of two modes power output. Finally, the simulation and experiment results verify the effectiveness of the proposed control strategy.