动态单元间交互作用对直流微电网稳定性影响的分析

Analysis on the Stability of DC Microgrid Affected by Interactions Among Dynamic Components

该文探究了动态单元交互作用如何影响直流微电网的稳定性,构建了由所研究目标动态单元构成的子系统和由微网剩余动态单元构成的子系统组成的闭环互联模型。针对子系统间的动态交互作用,通过模式分析的方法发现动态交互作用对稳定性作用的程度受到子系统开环动态特性的影响。当两个子系统开环振荡模式接近时,动态交互作用对系统阻尼的影响急剧增加,使得微网闭环振荡模式阻尼迅速降低。文章从模式条件的角度,揭示动态交互作用影响系统稳定性的机理,并提供量化评估的指标,以检验交互作用造成微网失稳的风险。最后,通过含换流器接口动态负荷与直流母线电压控制单元的微网算例验证该文分析和方法的有效性。

This paper investigated the stability of a DC microgrid affected by dynamic interactions among integrated components.The investigation was based on an interconnected model of microgrid with two subsystems.One subsystem was constituted by the examined dynamic component(EDC),and the other subsystem consisted of remainder of DC microgrid(ROM).Analysis was carried out in this paper to examine how the degree of interactions affected by modal condition of two subsystems.It was found when one open-loop oscillation of the examined component was in the proximity of a mode of the ROM subsystem on the complex plane,dynamic interaction turn strong,corresponding closed-loop oscillation moded of DC microgrid might move towards opposite directions as influenced by the coupled components,leading to growing oscillation instability case.Hence this investigation revealed the mechanism about why dynamic interactions inside the DC microgrid might cause instability from perspective of modal condition,and how interaction intensity was affected by the dynamic characteristics of subsystems.An examination method is proposed to detect stability danger by using modal information of subsystems.Finally,study cases of example DC mcirogrids with line regulating converters(LRCs)and converter-interfaced dynamic loads(CDLs)are presented to demonstrate the analysis made above.