基于虚拟频率的直流微电网下垂控制策略  

A Virtual Current-Frequency Droop Control in DC Microgrid

作　　者：刘彦呈[1] 庄绪州 张勤进[1] 朱鹏莅 郭昊昊[1] Liu Yancheng;Zhuang Xuzhou;Zhang Qinjin;Zhu Pengli;Guo Haohao(Marine Engineering College,Dalian Maritime University,Dalian 116026,China)

机构地区：[1]大连海事大学轮机工程学院,大连116026

出　　处：《电工技术学报》2021年第8期1693-1702,共10页Transactions of China Electrotechnical Society

基　　金：国家自然科学基金项目(51979021,51709028);中央高校基本科研业务费专项资金项目(3132019317);辽宁省计划项目(2019JH8/10100045);“双一流”建设专项(BSCXXM009)资助。

摘　　要：在直流微电网的传统下垂控制中,电路参数及线路阻抗的不一致造成DC-DC变换器下垂特性均存在差异,降低了变换器的均流精度。下垂控制还会造成一定程度的直流母线电压跌落。为了提高直流微电网的控制性能,模拟交流微电网的频率下垂控制机理,提出一种基于虚拟频率的多DC-DC变换器下垂控制方法。在控制器中构造了频率与输出电流成比例的虚拟交流量,利用低带宽通信共享各变换器的虚拟频率并求出平均值。该平均频率及虚拟交流量进一步用于产生虚拟无功功率以调整变换器的电压设定点,协调各变换器输出电流的大小。在不造成母线电压跌落的前提下,提高了多变换器间的负载电流分配精度。利用小信号模型分析虚拟频率下垂控制的闭环稳定性。最后,通过仿真和基于Starsim和dSPACE快速原型样机的实验,验证了该方法的有效性。In DC microgrid,the inconsistency of DC-DC converter parameters and line impedance reduces the current sharing accuracy of droop control.Meanwhile,droop control inevitably causes DC bus voltage drop.To improve the current sharing performance among DC-DC converters,a droop control method based on virtual frequency is proposed by simulating the frequency droop control mechanism in AC microgrid.In the controller,a virtual AC variable whose frequency is proportional to the output current is constructed.The virtual frequency of each converter is shared by low bandwidth communication and the average value is calculated.The average frequency and virtual AC variable are further used to generate virtual reactive power to adjust the voltage setting point of the converter and coordinate the output current of each converter.On the premise of not causing bus voltage drop,the accuracy of load current distribution among converters is improved and the communication pressure is reduced.The stability of virtual frequency droop control is analyzed using small signal model.Finally,simulation and experiment based on Starsim and dSPACE verify the validity of the method.

关 键 词：直流微电网 虚拟频率 下垂控制 并联均流 DC-DC变换器 

分 类 号：TM46[电气工程—电器]