直流微网中基于SOC的改进下垂控制

并网直流微源的有效管理和控制是保证直流微网稳定运行的关键。下垂控制是直流微网中常用的管理和控制直流微源的一种方法,能够有效实现微源间功率分配。但传统的基于荷电状态(State of Charge, SOC)的下垂控制存在随着SOC减小直流母线电压跌落逐渐加剧的缺陷,针对该缺陷提出了一种基于SOC的改进下垂控制策略。首先给出了根据母线电压波动的下垂系数调整律,当母线电压跌落时会自动减小下垂系数。随后建立了以输出电容的电压和电流为状态量的系统控制模型,设计了电流内环电压外环的双环PI控制器。最后搭建了Matlab/Simulink仿真模型,对比仿真了四种不同因素影响下系统的控制性能。仿真表明所提出的改进下垂控制很好地实现了母线电压稳定和各微源功率按其SOC合理分配,并具有较强的抗负载变化能力。

Improved droop control based on SOC in DC microgrid

The effective management and control of grid-connected DC micro-sources is the key to ensure the steady operation of DC microgrid. Droop control is a common method to manage and control DC micro-sources in DC microgrid. However, the traditional droop control based on State of Charge (SOC) has the defect that the voltage drop of DC bus becomes worse with the decrease of SOC. Therefore, an improved droop control based on SOC is proposed. Firstly, the law of adjusting the droop coefficient according to the voltage fluctuation of the bus is given, which will automatically reduce the droop coefficient when the bus voltage drops. Meanwhile, a system control model with voltage and current of output capacitance as state variables is established, and a double-loop PI controller with current inner loop voltage outer loop is designed. Finally, Matlab/Simulink simulation model is built, and the control performance of the system under the influence of four different factors is compared and simulated. The simulation results show that the improved droop control can achieve the voltage stability of the bus and the reasonable distribution of the power of the micro-sources according to its SOC, and it has a strong ability to resist the load change. This work is supported by National Natural Science Foundation of China (No. 61703145).