DC Fault Detection in MTDC Systems Based on Transient High-frequency of Current
DC Fault Detection in MTDC Systems Based on Transient High-frequency of Current
复制标题
基于电流瞬态高频的多端直流系统直流故障检测
DOI：
10.1109/tpwrd.2018.2882431
复制
发表时间：
2018
影响因子：
4.4
通讯作者：
Zhao Xu
中科院分区：
文献类型：
--
作者：
Yujun Li;Lei Wu;Jiapeng Li;Liansong Xiong;Xian Zhang;Guobing Song;Zhao Xu
在基于电压源变换器（VSC）的多端直流（MTDC）系统中，故障后短时间内故障直流线路的隔离是一个主要的挑战。现有的防护方案设计主要基于数值模拟，缺乏理论分析。本文首次提出了基于vsc的MTDC系统的高频等效模型，用于故障电流的计算。基于直流故障分析，验证了高频故障电流分量在故障线路中流动，然后在健康线路中急剧衰减。据此，提出了一种新的基于vsc的MTDC系统直流故障检测方法。该方法利用线路电流的瞬态高频能量，可以在不通信的情况下快速识别故障线路。此外，还研究了长传输线上出现的暂态行波对所提出的保护方案的影响。在PSCAD/EMTDC中进行的大量仿真研究表明，所提出的高频等效模型可以用于基于vsc的MTDC系统的初始直流故障分析，并且所提出的保护方案在不同时间窗、不同故障位置和高故障电阻下都是有效的。与现有基于电流的保护方案的变化率相比，本文提出的初级保护所需的采样频率较低，对参数变化不敏感，对外界噪声和数据缺失具有较高的鲁棒性。
Isolation of the fault dc lines during the initial short period after fault is a major challenge in the multi-terminal dc (MTDC) system based on a voltage-source converter (VSC). Existing protection schemes are mainly designed based on the numerical simulations, which lacks the theoretical analysis. In this paper, a high-frequency equivalent model of a VSC-based MTDC system is first proposed for the fault current calculation. Based on the dc fault analysis, it is validated that the high-frequency fault current components flow in the fault line and then dramatically decay in the healthy line. Accordingly, a novel dc fault detection method for the VSC-based MTDC system is proposed. In the proposed approach, the primary protection utilizes the transient high-frequency energy of line current and the fault line can be identified quickly without communication. In addition, the influence of the transient traveling-wave appearing on the long-transmission line on the proposed protection scheme is also investigated. Numerous simulation studies carried out in PSCAD/EMTDC have demonstrated that the proposed high-frequency equivalent model can be utilized for the initial dc fault analysis of the VSC-based MTDC system and the proposed protection scheme is effective in different time windows, different fault locations, and high fault resistances. Compared with the existing rate of change of current-based protection scheme, the proposed primary protection requires relatively low sampling frequency, is insensitive to the parameter changes, and has high robustness with respect to the outside noises and data missing.