直流微网接地综述与基于控保协同的保护方法研究初探

Review of DC Microgrids Grounding and Study on Protection Methods Based on Control and Protection Cooperation

直流微网可能会对用户供电方式带来变化,该文旨在系统阐述与其保护技术相关内容的研究现状。首先,明确了所研究直流微网的电压等级以及相关的电力电子器件,在此基础上根据运行性能和成本等因素总结了被广泛接受的接线方式。然后,总结了与接地方式相关的多个性能指标并对重要的部分做出解释,在空间上从交流网侧、交流阀侧、直流系统侧和用户侧4个方面阐述了直流微网接地方式的选择,之后讨论了直流侧接地点个数的选择并提出了现有文献对接地选择的争议。最后,总结了各类元件的极间故障特征,并在接地方式的基础上对各种接地故障特征进行了讨论分析。该文简单介绍了现有保护方案,并针对其局限性以及电力电子器件可控的特点,从器件和系统2个方面阐述了基于控保协同的保护方法。最后展望了与直流微网保护密切相关的接地方式、故障分析以及保护方法的研究方向。

DC microgrids may bring changes in power supply methods for users,and the purpose of this article is to systematically explain the research status of its protection technology.First,we clarified the voltage level of the DC microgrids under study and the related power electronic devices.On this basis,we summarized the widely accepted wiring methods based on factors such as operating performance and cost.Then,we summarized the multiple performance indicators related to the grounding method and explained the important parts.We explained the DC microgrids grounding method from the four aspects of the AC grid side,the AC valve side,the DC system side,and the user side.Moreover,we discussed the choice of the ground afterwards and the choice of the number of grounding points on the DC side.Finally,we summarized the characteristics of bipolar faults and discussed the characteristics of various ground faults based on the grounding method.Meanwhile,we briefly introduced the existing protection schemes,and explained the protection method based on the coordinated control and protection in terms of its limitations and the controllable characteristics of power electronic devices from two aspects:device and system.Finally,the research directions of grounding methods,fault analysis and protection methods closely related to DC microgrids protection are prospected.