摘要
含分布式电源的配电网发生单相短路故障时,各相短路电流的分布情况随分布式电源容量的变化而发生变化,但各线路首端零序电流的特征不会改变,即全系统健全线路的零序电流之和等于故障线路首端的零序电流,且两者的非工频零序电流的方向相反,可继续利用这一特征识别故障线路。利用希尔伯特-黄变换提取各线路的非工频零序电流分量,再求取各线路非工频零序电流的能量权重系数;利用数字陷波器取出各零序电流的5次谐波分量。当5次谐波分量有相同极性时,故障发生在母线上;当某条线路的能量权重系数最大,且其他线路5次谐波分量的极性与该条线路相异时,故障发生在该条线路上。通过仿真实验证明,该方法适用于小角接地故障、高阻接地故障及线路末端故障等不利于实现选线的故障,且该方法有较高的准确度和可靠性。
The distribution of each phase short-circuit current can be changed by the variation of the distributed generation capacity when the single phase ground fault occurs in the distribution network. But it cannot change the characteristics of the zero-sequence current in the head of each line,i. e. the sum of the zero-sequence currents in the non-fault lines equals the head line zero-sequence current in the fault line but they have the inverse direction for the non-power frequency zero-sequence currents. This feature can be used as a fault line selection criterion. This paper proposes a novel method using Hilbert-Huang transform algorithm to extract the nonpower frequency component of the zero sequence current in each line, and calculates their energy weighting coefficient. Then the digital notch filter is used to extract the 5thharmonic current of the zero sequence current. It can be concluded that：（ 1） the fault occurs in the bus if the direction of the 5thharmonic current is same; and（ 2） when one line has the largest energy weight coefficient and its direction of the 5thharmonic current is different from others,the fault occurs in the line. Through simulations,the proposed method is proved to be able to select the fault line accurately and reliably in the difficult cases,i. e. the small angle fault,the high-impedance ground fault,and the fault in the end of line and etc.,with high accuracy and reliability.
出处
《电工技术学报》
EI
CSCD
北大核心
2015年第17期96-105,共10页
Transactions of China Electrotechnical Society
基金
欧盟FP7国际科技合作基金(909880)
国家自然科学基金(50907011)
福建省杰出青年科学基金(2012J06012)
福建省高校杰出青年人才培育基金(JA1108)资助项目
