Pole-to-ground Fault Analysis for HVDC Grid Based on Common-and Differential-mode Transformation

• 作者: Jiabing Hu Lei Lin Yuanzhu Chang Zhen He Zhiyuan He
• 来源期刊: 现代电力系统与清洁能源学报(英文)
• 学科: 工学
• 关键词: High-voltage direct current(HVDC)grid pole-to-ground(PTG)fault common-and differential-mode(CDM)transformation DC ciruit breaker(DCCB)
• 年，卷（期）: 2020,（3）
• 页码范围: 521-530
• 页数: 10页
• 分类号: TM7

摘要

Pole-to-ground(PTG) fault analysis is of vital importance for high-voltage direct current(HVDC) grid. However, many factors are not considered in the existing studies such as the asymmetrical property of PTG fault, the coupling issue between DC transmission lines and the complexity of the structure of DC grid. This paper presents a PTG fault analysis method, which is based on common-and differential-mode(CDM)transformation. Similar to the symmetrical component method in AC system, the transformation decomposes the HVDC grid into CDM networks, which is balanced and decoupled. Then, a transfer impedance is defined and calculated based on the impedance matrices of the CDM networks. With the transfer impedance, analytical expressions of fault characteristics that vary with space and time are obtained. The proposed PTG fault analysis method is applicable to arbitrary HVDC grid topologies,and provides a new perspective to understand the fault mechanism. Moreover, the analytical expressions offer theoretical guidance for PTG fault protection. The validity of the proposed PTG fault analysis method is verified in comparison with the simulation results in PSCAD/EMTDC.