直流配电网光伏变流器柔性出力自适应分段下垂控制

在含光伏的直流配电网系统中,传统的下垂控制在光伏出力变化的情况下,存在功率分配不均衡及母线电压偏差大等问题。针对光伏出力受环境因素影响较为严重,引起传统下垂控制效果变差这一问题,根据光伏出力变化情况自适应调节下垂特性曲线,使其在重载条件下实现功率的精确分配,在轻载条件下,实现母线电压的稳定控制。通过建立下垂控制输出阻抗模型,分析了下垂系数自适应变化对系统环流抑制能力及均流度的影响。在MATLAB/Simulink中搭建光伏直流配电网进行仿真验证。理论分析和仿真验证表明所提光伏变流器柔性出力自适应分段下垂控制能够按照光伏电源出力动态调节功率分配任务,在重载时可以提高系统功率分配精度,轻载情况下可以减小直流母线电压偏差。

Adaptive Segmented Droop Control for Flexible Output of Photovoltaic Converter in DC Distribution Network

In a DC distribution system with photovoltaic power, according to traditional droop control, when photovoltaic power output changes, there will be problems such as unbalanced power distribution and large deviation of bus voltage. Photovoltaic power output is seriously affected by environmental factors, which causes the effect of traditional droop control to deteriorate. In response to this problem, the droop characteristic curve can be adaptively adjusted according to the changes in the photovoltaic output, so that it can achieve accurate power distribution under heavy load conditions. At the same time, this solution can also achieve stable control of the bus voltage under light load conditions. Through the establishment of the output impedance model of droop control, the influence of the adaptive change of droop coefficient on the system's circulation suppression and current sharing is analyzed. In addition, a DC distribution network with photovoltaic power is built in MATLAB/Simulink for simulation verification. A combination of theoretical analysis and simulation verification shows that the proposed adaptive segmented droop control for flexible output of photovoltaic converter can dynamically adjust the power distribution task according to the photovoltaic power output. Specifically, the system power distribution accuracy can be improved when the load is heavy, and the DC bus voltage deviation can be reduced when the load is light.