光伏发电系统多模式接入直流微电网及控制方法

对接入直流微电网的光伏发电系统提出三种工作模式,即最大功率点跟踪控制模式、恒压模式和恒功率模式。在最大功率点跟踪控制模式时,采用一种变步长的扰动观察法实现最大功率点跟踪。在恒压模式时,采用PI控制实现恒压控制。在恒功率模式时,采用PI控制实现恒功率控制。当判断出不能实现恒压或恒功率控制时,切换到最大功率点跟踪控制模式,并通知能量管理器,能量管理器通过储能装置调度或负荷调度来镇定直流母线电压。从而使光伏发电系统对能量管理器来说是一个受限的可控源,有助于直流微电网的稳定运行。对所提出的多种工作模式及控制方法进行了仿真,结果表明,所提方法能使光伏发电系统运行于多种工作模式,并能实现相应的控制目标及模式切换,使光伏发电系统变为一个受限的可控源。

Multimode of photovoltaic generation system connected to DC microgrid and control methods

Three operating modes are presented for photovoltaic (PV) generation systems connected to DC microgrid, including the maximum power point tracking (MPPT) control mode, constant voltage mode and constant power mode. A variable step size perturbation and observation method is used to achieve maximum power tracking in the MPPT control mode. The constant voltage control is achieved by the PI control method in the constant voltage mode. The constant power control is achieved by the PI control method in the constant power mode. When the constant voltage or constant power can not be realized, the operating mode is switched to the MPPT control mode and the energy manager is notified. The DC bus voltage is stabilized by the energy storage device dispatch or the load dispatch. So that the PV generation system is a controllable source of limited to the energy manager and is contributed to the stable operation of the DC microgrid. The multimode and control methods are simulated, and the results show that the PV generation system can operate in multimode, and the control objectives and mode switching can be achieved. Therefore, the PV generation system is changed into a controllable source of limited.