城市微电网接地系统选择与设计

Design and Selection of the Grounding Systems for City Micro-grid

为获得适合城市微电网的接地方案,文中基于城市微电网接地案例在PSCAD/EMTDC中搭建3种不同接地方式(TN、TT及IT)的仿真模型,研究了各接地系统故障电流水平,仿真验证了过流保护及剩余电流动作保护的灵敏性;基于仿真模型,分析了总等电位联接下TN接地系统的安全性,并提出非等电位联接下TT及IT接地系统要配置快速可靠的剩余电流动作保护装置。综合各接地系统优缺点,获得适用于城市微电网案例的混合接地系统。

In order to obtain a safe and reliable grounding scheme of micro-grid,this paper builds three different grounding models（TN, TT and IT）through the PSCAD/EMTDC in the standard micro-grid model proposed by Eu- ropean ICCS/NTUA. The fault current level of various grounding systems is studied. This paper has verified the importance of RCD and over current protection to react load shell fault through simulation in grounding system. In the security of different grounding system,based on the simulation model,the security of TN grounding system under the total equipotential connection is analyzed, and non-equipotential connection should be configured quickly and reliably RCDs in both TT and IT grounding system. Through the analysis of fault current level, effects and security, a hybrid grounding system is proposed at last.