多端柔性直流配电网接地方式设计  

Grounding Method Design of Multi-terminal Flexible DC Distribution

作　　者：吴峻[1] 武迪 朱金大 洪莎莎 骆健 俞拙非 董长城 

机构地区：[1]国网江苏省电力公司南京供电公司,江苏省南京市210019 [2]南京南瑞集团公司,江苏省南京市210006 [3]江苏省电力公司经济技术研究院,江苏省南京市21000

出　　处：《中国电机工程学报》2017年第9期2551-2560,共10页Proceedings of the CSEE

基　　金：国家重大科技专项(2016YFB0901805);南瑞集团公司科技项目(524606150143)~~

摘　　要：多端柔性直流配电网是柔性直流输电技术与配电网相结合的新型应用形式,该配网技术采用多端电压源换流器构建跨台区低压直流互联系统,利用优化下垂控制实现台区间基于配电变容比(容量比例)的自适应潮流转供。针对所采用的电压源换流器,推导出其稳态零序等效电路,并得出零序入地电流的计算式。通过分析电压源变流器直流侧不同接地方式下稳态零序入地电流、交流侧滤波器不同接地方式下滤波效率及交流滤波器共模电压,提出直流侧不接地、交流滤波器直接接地具有较优的稳态运行特性。基于PSCAD/EMTDC建立了4台区等值配电网的多端柔性直流配电网电磁暂态模型,以交流阀侧单相接地故障及直流侧单极接地故障为典型暂态故障场景,对比分析了不同接地方式下的交/直流侧故障电流水平、直流母线电压波动及故障电压恢复特性等暂态特性,结论验证了所选接地方式同时具有优越的暂态故障特性。Multi-terminal flexible DC distribution is a new application form of combination of voltage source converter based high voltage direct current （VSC-HVDC） and distribution system. This distribution technology constructs a cross-distribution-areas low-voltage DC interconnected system using multi-terminal voltage source converter （VSC）, and implements adaptive power flow transferring supply among distribution areas according to distribution transformers capacity ratio using optimized droop control. Zero-sequence steady equivalent circuit of VSC adopted was derived and calculation formula of zero-sequence grounding current was obtained. By analyzing steady zero-sequence grounding current of different DC-side grouding methods, analyzing filtering efficiency ＆ common mode voltage of different AC-side grouding methods, a mode of AC filter direct grounding and DC capacitor ungrounding was proposed to achieve an optimal steady runing condition. A multi-terminal flexible DC distribution simulation model of 4-distribution-areas equivalent-network was established based on PSCAD/ EMTDC. Single-phase grounding fault at AC valve side and DC monopole grounding fault were set as typical transient fault scenes, characteristics of fault current of DC/AC side, DC voltage fluctuation and fault-recovery characteristic etc. were comparatively analyzed, results verified chose grounding method also achieve a beneficial transient fault characteristics.

关 键 词：多端柔性直流配电网 接地方式 零序入地电流 稳态运行特性 故障暂态特性 

分 类 号：TM721.1[电气工程—电力系统及自动化]