基于柔性工作点追踪的光伏低电压穿越控制策略

为解决现有光伏并网发电系统低电压穿越控制存在的母线过电压问题，提升并网系统故障恢复能力，本文结合柔性工作点追踪控制原理，提出一种经济有效的基于柔性工作点追踪的低电压穿越控制策略。首先，通过图形近似法快速估算出减载点工作电压，推导出故障期间光伏参考工作点位置，提出光伏输出功率快速减载策略；其次，利用拟合出的光伏电流-电压曲线估算光伏短路电流，通过Lambert-W函数计算出最大功率点电压，进一步提出故障快速恢复策略；最后，本文分别通过Matlab仿真和硬件在环测试平台进行仿真和实验分析。分析结果验证了所提控制策略有较好的故障穿越能力和故障恢复效果，且经济性较好，有助于光伏并网发电技术的推广应用。

Photovoltaic low-voltage ride-through control strategy based on flexible power point tracking

In order to solve the DC bus overvoltage problem of existing low voltage ride through (LVRT) control in photo-voltaic (PV) grid-connected systems as well as improve the fault recovery capacity of the grid-connected system, this paper takes into account the control principle of flexible power point tracking (FPPT) and proposes a cost-effective LVRT control strategy based on FPPT. To begin with, the graphical approximation method is used to quickly estimate the operating voltage of the power curtailment point and deduce the position of the photovoltaic reference operating point during the fault process, based on which a rapid active power curtailment control strat-egy is proposed. Subsequently, the voltage against current curve of PV is fitted, from which the photovoltaic short-circuit current is estimated, the voltage of maximum power point calculated using the Lambert-W function, and the fast recovery control for faults proposed. Finally, MATLAB simulation and hardware-in-the-loop (HIL) testing platform are respectively employed to carry out simulation analysis and experimental analysis for verifi-cation. The results prove that not only can the proposed control strategy facilitate decent fault ride through and fault recovery, but it also offers fair cost-effectiveness, all of which contribute well to the cause of practical pop-ularization in the grid-connected photovoltaic power generation technology.