一种直流微电网多光伏变换器新型功率分配策略

为了解决光伏单元在运行过程中因工作模式切换造成的母线电压波动问题，提出一种新型平滑切换控制策略。根据光伏电池的输出特性曲线，将输出功率对输出电流的微分作为控制变量。通过跟踪不同的dp/di指令值来实现光伏单元最大功率点跟踪模式、恒压下垂模式的控制以及两种模式间的平滑切换。在此基础上，针对多光伏变换器工作在恒压下垂控制时因线路阻抗差异造成功率分配精度较低的问题，提出一种基于二次调节的自适应下垂控制策略。此外，构建相邻光伏单元间的稀疏通信网络，并采用动态一致性算法实现相关平均信息的全局稳定收敛。仿真和实验结果表明，所提控制策略可以实现光伏单元工作模式切换过程平滑过渡和负荷功率的精确分配。

A novel power sharing strategy for multi photovoltaic converters in a DC microgrid

To solve the problem of bus voltage fluctuation caused by the switching of working modes during the operation of a photovoltaic unit, a novel smooth switching control strategy is proposed. From the output characteristic curve of the photovoltaic cell, the differential of the output power to the output current is used as the control variable. By tracking different dp/di command values, the PV converter can realize the control of MPPT mode, CVD mode and smooth switching between the two modes. To solve the problem of low power distribution accuracy caused by the difference of line impedance when multiple photovoltaic converters work in the CVD mode, an adaptive droop control strategy based on secondary regulation is proposed. In addition, a sparse communication network between adjacent photovoltaic units is constructed, and a dynamic consensus algorithm is used to achieve global stable convergence of related average information. The simulation and experimental results show that the proposed control strategy can realize the smooth transition of the PV unit working mode switching process and the precise sharing of load power. This work is supported by the National Natural Science Foundation of China (No. 51709028 and No. 51979021).