中文摘要：

单相光伏并网发电系统采用LCL滤波器有利于抑制高频开关谐波电流进入电网，但是LCL滤波器增加了系统的阶数，增大了系统稳定性的设计难度。直流侧电压外环、网侧电流内环的双环控制策略适用于采用L或者LC滤波器的单相光伏并网发电系统，但不利于基于LCL滤波器系统的稳定性。提出一种电压环、功率环和电容电流环的并网控制策略，电压环稳定并网逆变器直流侧电容两端的电压，功率环调节光伏并网发电的功率因数，功率环和电容电流环共同提高系统的稳定性和抑制LCL滤波器引起的谐振尖峰。推导了系统的闭环传递函数，分析了控制参数对系统闭环极点分布和稳定性的影响。仿真和实验结果验证了所提控制策略的可行性。

英文摘要：

Single-phase photovoltaic grid-connected generator systems adopt LCL filter which is useful to restrain high-frequency switching current into the grid. However, the LCL filter increases the system order so that the design of the system stability is difficult to be realized. At present, dual-loop control strategies which consist of dc-side voltage outer loop and grid-side current inner loop have been widely used for single-phase photovoltaic grid-connected generator systems with L or LC filters. But if the dual-loop control is directly used in the photovoltaic system with the LCL filter, the system may be unstable. This paper presented a novel grid-connected control strategy composed of voltage loop, power loop, and capacitor current loop. The voltage loop stabilized the capacitor voltage at dc-side of the grid-connected inverter; the power loop regulated the power factor of photovoltaic grid-connected generating power; both the power loop and the capacitor current loop improved the system stability and suppress resonant peak caused by the LCL filter. The system closed-loop transfer function was derived and the influence of control parameters on the system stability was analyzed with the closed-loop pole distribution. Simulation and experiment results demonstrate the feasibility of the proposed control system.