摘要
针对传统下垂控制中功率分配和电压调整的矛盾性,结合直流微网的结构特点,提出一种可抑制并联变流器间环流、准确分配负荷功率,同时稳定直流母线电压的改进下垂控制策略。首先,在各变流器输出端引入虚拟电阻,以功率损耗最小为目标确定其初始值,根据各变流器输出电压差自适应调整虚拟电阻大小,抑制环流的同时尽可能减小母线压降;其次,在控制器输入端引入电流补偿控制,消除线路电阻对功率分配精度的影响,采用分布式电压补偿控制进一步调整母线电压;最后,利用系统特征方程式分析系统的稳定性,为实际工程中设计变流器控制器提供理论指导。仿真验证了所提控制策略的有效性。
There are contradictoriness between voltage regulation and load sharing in traditional droop control strategy. Combined with characteristics of DC microgrid, an improved droop control strategy was proposed to insure the stability of DC bus voltage and accuracy of load sharing.Meanwhile, this strategy is effective to restrain the circulating current between parallel inverters.Firstly, the virtual resistance was imported into the output of each inverter, the initial value of the virtual resistance was determined aiming at reaching the minimum power loss, and the value was adjusted adaptively based on the output voltage difference between inverters to restrain the circulating current and reduce the bus voltage drop as much as possible. Then, a compensation current control was introduced to the input of controller to eliminate the impact of line resistance on the accuracy of load sharing, and the distributed voltage compensation control was applied to regulate bus voltage further. Finally, the characteristic equation of the system was utilized to analyze the stability of the system, and the proposed control strategy provided a theoretical guidance for engineering. Simulation experiments verified the effectiveness of the strategy.
出处
《可再生能源》
CAS
北大核心
2017年第1期72-79,共8页
Renewable Energy Resources
关键词
直流微网
并联变流器
环流抑制
改进下垂控制
自适应虚拟电阻
DC microgrid
parallel inverter
circulating current
improved droop control
adaptive virtual resistance
