直流微网中PV发电系统的改进型恒压控制策略

IMOROVED CONSTANT VOLTAGE CONTROL OF PV POWER GENERATION SYSTEM IN DC MICROGRID

直流微网中光伏(PV)系统的控制策略会影响整个微网稳定性能。当微网中出现功率冗余时,需要减少PV系统的发电功率,PV系统需从最大功率点跟踪(MPPT)工作模式切换到限功率(非MPPT)工作模式。目前常用的限功率工作模式为恒压控制,但恒压控制稳定性差,对光伏P-U特性曲线上一些区段工作点不能稳定控制。由此该文提出改进型恒压控制,能对光伏P-U特性曲线上的所有工作点稳定控制。在Matlab/Simulink软件上仿真PV系统独立运行时和PV系统在微网中运行时的稳定性,仿真结果验证本文所提的改进型恒压控制可解决恒压控制存在的问题。

The control strategy of photovoltaic(PV)system has great effect on the stability of whole microgrid system. If the power redundancy occurs in microgrid,it is needed to reduce the power of PV system,the operating mode of PV system needs to switch from maximum power point tracking(MPPT)mode to limited power(non MPPT)mode. The constant voltage control is commonly used in limited power mode,but its stability is bad,and it cannot be stably controlled on some part of the PV P-U characteristic curve. Therefore,the improved constant voltage control strategy is innovatively proposed in this paper,it can achieve stability control for all the points on the PV P-U characteristic curve.Finally,the stability of PV system on isolated operation and the stability of PV system that is integrated into microgrid system are simulated on Matlab/Simulink software. The simulation results show that the improved constant voltage control can solve the problems of constant voltage control.