直流微网双向DC/AC变流器的协调控制

Coordinated Control of Bidirectional DC/AC Converters in DC Microgrid

直流微网并网运行时,常通过多个双向DC/AC变流器实现与大电网的互联。为实现该工况下系统稳定运行并解决多台双向DC/AC变流器并联功率分配问题,提出了一种双向DC/AC变流器的交流功率-直流电压下垂控制方法。该方法通过测量变流器交流侧有功功率,按照预设下垂曲线调节直流侧电压指令值,实现直流微网与电网功率双向流动,以及多台双向DC/AC变流器的协调运行。其次,建立了所提控制方法的小信号模型,分析了下垂系数对系统稳态及动态性能的影响。最后,仿真与实验结果表明,所提控制策略可按照预设下垂曲线调节直流母线电压和进行多台双向变流器功率分配,快速响应上层调度指令以及直流微网内功率变化,具有较好的动稳态性能。

When the DC microgrid is connected to the grid,multiple bidirectional DC/AC converters are often used to achieve interconnection with power grid.In order to achieve stable operation of the system under this working condition and solve the power distribution problem of multiple bidirectional DC/AC converters in parallel,an AC power-DC voltage droop control of bidirectional DC/AC converter is proposed.This method regulates the DC side voltage reference according to a preset droop curve and measured AC-side active power to realize bidirectional power flow between DC microgrid and power grid,and the coordinated operation of multiple bidirectional DC/AC converters.Secondly,a small signal model of the proposed control method is established,and the influence of the droop coefficient on system steady and dynamic performance is analyzed.Finally,the simulation and experimental results show that the proposed control strategy can adjust the DC bus voltage and achieve power distribution of multiple bidirectional converters according to the preset droop curve,quickly respond to upper-level dispatch commands and power changes in the DC microgrid,presenting good dynamic and steady performance.