双有源全桥DC-DC变换器的自适应虚拟直流电机控制方法

Adaptive Virtual DC Machine Control Strategy for Dual Active Bridge DC-DC Converter

针对直流电网中微源功率突变、负荷投切、大电网扰动等造成的直流电压暂降问题,在分析了直流电机并网后动态调压特性的基础上,提出一种适用于直流电网的自适应虚拟直流电机控制方法(adaptive virtual DC machine control strategy,AVDCM),并将其应用于储能端的双有源全桥(dual active bridge,DAB)DC-DC变换器接口。该控制使换流器模拟出直流电机的惯性特性,在电压暂降瞬间提供良好的动态功率支持;在控制环节中加入了模糊逻辑控制器,通过检测直流母线电压的变化率与换流器的剩余容量,灵活调节惯性支持的响应速度和大小。基于建立的四端系统小信号模型,进行了灵敏度计算与根轨迹分析,以揭示主要控制参数对系统稳定性及动态性能的影响。硬件在环测试结果表明:所提控制方法在保持换流器良好功率跟踪性能的同时,可使变换器在阶跃与随机性功率波动下提供灵活可调的惯性支持,从而有效减缓系统受到的瞬时功率冲击,减少电压暂降幅度,进而提升电压质量。论文研究可为双有源全桥DC-DC变换器自适应虚拟直流电机的控制提供参考。

Based on the analysis of dynamic voltage regulation characteristics of the DC machine connected to the grid,an adaptive virtual DC machine control strategy(AVDCM)for the DC grid is proposed to solve the problems of the DC voltage dip caused by sudden power change of micro-source,load switching and power disturbance of AC grid,and the strategy is applied to the interface of the dual active full-bridge DC-DC converter in the energy storage unit.In the strategy,the converter is made to simulate the inertial characteristics of the DC machine and provide good dynamic power support at the moment of voltage sag.A fuzzy logic controller is added to the control link to flexibly adjust the response speed and magnitude of the inertial support by detecting the change rate of DC bus voltage and the residual capacity of the converter.Based on the established small-signal model of the four-terminal system,sensitivity calculation and root locus analysis are carried out to reveal the influences of main control parameters on system stability and dynamic performance.Test results of hardware in the loop show that the proposed control method can provide flexible and adjustable inertial supports under the step and random power fluctuation while maintaining the good power tracking performance of the converter,which effectively mitigates the instantaneous power impact on the system,reduces the voltage dip and improves the voltage quality.The research of the paper can provide references for the control of adaptive virtual DC machine for dual active full-bridge DC-DC converter.