基于环路增益的直流微网母线阻抗在线估计和阻尼方法

On-line Bus Impedance Estimation and Damping Method of DC Microgrid Based on Loop Gain

直流微网通常由多个含反馈控制的电力电子变换器连接到普通直流母线上构成。虽然每个单独的变换器的控制回路设计具有良好的稳定裕度,但由于潜在的相互作用,多个电源和负载变换器的互连会导致稳定性问题。因此,为了确保互连电力转换器系统的动态性能,一个值得研究的方法就是对直流母线进行在线稳定性监测,并适当地阻尼直流母线阻抗。首先,根据源侧变换器的电压或下垂环路增益推导了直流母线阻抗的表达式。其次,基于相位裕度的系统动态行为的指标给出母线阻抗峰值的估计。接着,提出只需在电压(或下垂)回路中注入一个正弦信号,即可连续监测母线阻抗峰值。然后,根据监测的值自动调整电压调节器,以保持母线阻抗在一个众所周知的允许阻抗区域。最后,通过仿真和实验验证了所提方法的有效性和优越性。

DC microgrid usually consists of a plurality of power electronic converters with feedback control connected to a common DC bus.Although the control loop design of each individual converter has a good stability margin,the interconnection of multiple power and load converters can cause stability and performance problems due to potential interactions.Therefore,in order to ensure the dynamic performance of the interconnected power converter system,a method worth studying is to monitor the on-line stability of the DC bus and dampen the impedance of the DC bus properly.Firstly,the expression of DC bus impedance was derived from the voltage or droop loop gain of source-side converter.Secondly,the estimation of busbar impedance peak was given based on the dynamic behavior index of the system with phase margin.Then,it was proposed that the peak impedance of the bus can be monitored continuously by injecting a sinusoidal signal into the voltage(or drooping)loop.Then,the monitored values can be used to automatically adjust the voltage regulator to keep the bus impedance in a known allowable impedance region.Finally,the effectiveness and superiority of the proposed method were verified by simulation and experiment.