两台电力电子变压器并列运行时直流侧接地方式的研究  

DC Side Grounding Mode of Two Power Electronic Transformers in Parallel Operation

作　　者：李潇 范春菊[1] 姜山[1] 王圣辉 金甚达 LI Xiao;FAN Chunju;JIANG Shan;WANG Shenghui;JIN Shenda(School of Electronic Information and Electrical Engineering,Shanghai Jiao Tong University,Minhang District,Shanghai 200240,China)

机构地区：[1]上海交通大学电子信息与电气工程学院,上海市闵行区200240

出　　处：《电网技术》2020年第12期4783-4791,共9页Power System Technology

基　　金：国家重点研发计划项目(2017YFB0903201)。

摘　　要：交直流混合电网的系统结构有利于接入分布式能源及直流负荷,是未来电网的发展方向。以2台电力电子变压器(power electronic transformer, PET)并列运行的交直流混合电网作为典型研究对象,对PET直流端口接地方式进行了研究。首先,建立了2台PET并列运行的电网模型,每台PET包括4个不同电压等级的输出端口。基于搭建模型,详细分析了单极金属回路运行方式与伪双极运行方式2种运行方式下的直流侧单极接地故障回路,给出了结构对称时的单极金属回路运行方式下的故障电流与电压解析表达式,并进行仿真试验。最后,基于PSCAD/EMTDC平台,对直流侧单极接地故障进行仿真研究,给出接地方式的建议:单极金属回路运行方式下至少有一台PET采用零极线路经电阻接地方式,伪双极运行方式下至少有一台PET采用并联大电阻中点接地方式。The system structure of AC/DC hybrid power grid is conducive to the access of distributed energy and load, and it is the future direction of power grid development. In this paper, the AC/DC hybrid power grid with two power electronic transformers(PET) running in parallel is taken as the typical research object, and the DC port of PET grounding mode is studied. Firstly, the grid model with two parallel PETs is established, in which each PET has four output ports with different voltage levels. Based on this model, the DC side single-pole grounding fault circuits under both the single-pole metal circuit operation mode and the pseudo-bipolar operation mode are analyzed. The analytical expressions of fault current and voltage under the operation mode of single-pole metal circuit with symmetrical structure are proposed, and the simulation is also carried out. Finally, based on PSCAD/EMTDC platform, the simulation of DC side single-pole grounding fault is studied. The grounding mode suggestions are given: under the single-pole metal circuit operation mode, there should be at least one PET grounded by zero-pole line through resistance;while under the pseudo-bipolar operation mode, there should be at least one PET grounded by parallel high-resistance neutral point.

关 键 词：并列运行PET 故障特性 直流端口 故障瞬时过电流 接地方式 

分 类 号：TM721[电气工程—电力系统及自动化]