基于改进双闭环控制的光伏并网系统研究

光伏并网系统在光照太强的情况下往往出现输入功率与输出功率不匹配,导致直流母线电容上电压过高的危害.针对这一现象提出一种新型的控制策略,对Boost电路采用三环控制的方案,即传统的电压外环和电流内环再加上直流母线电压保护环,使电路在直流母线电容电压上升时,能自动调节输入功率以匹配输出功率,保证系统额定功率输出,避免系统因直流母线过电压故障导致的系统功率丢失,以提高光伏并网系统工作的可靠性.文中采用两级式结构的单相光伏并网系统,对其控制系统进行了详细地分析设计,并通过PSIM软件进行仿真,验证了该控制策略的有效性.

Photovoltaic Grid-connected System Based on Modified Dual Closed-loop Control

Mismatching of input and output power often happens under high-intensity illumination in photovoltaic grid-connected systems,which may cause excessive voltage of DC-bus.To solve this problem,the paper proposed a novel control strategy,which employed three-loop control scheme in Boost circuit including traditional voltage loop,current inner-loop plus DC-bus voltage protection-loop.The approach would automatically coordinate the input power to match output power when the voltage of DC-bus capacitor was rising,which could ensure the rated output power,avoid the power loss due to the high voltage failure of DC-bus and therefore improve the reliability of the grid-connected systems.This research adopted single-phase double-stage structure,analyzed the control system design in details,and finally verified its validity through the simulation PSIM.