Optimization scheme for differential protection of low frequency transmission line based on equivalent sequence impedance difference characteristics

被引：0

作者：

Huang T. ^{[1
]}

Wen J. ^{[1
]}

Zhao Q. ^{[1
]}

Xu X. ^{[1
]}

Xie H. ^{[1
]}

Xu H. ^{[1
]}

Bu L. ^{[1
]}

机构：

[1] NR Electric Co.，Ltd., Nanjing

来源：

Dianli Zidonghua Shebei/Electric Power Automation Equipment | 2024年 / 44卷 / 05期

关键词：

braking coefficient; control strategy; controlled fault characteristics; differential protection; equivalent sequence impedance; low frequency transmission; relay protection;

D O I：

10.16081/j.epae.202403012

中图分类号：

学科分类号：

摘要：

During the fault of low frequency transmission line（LFTL），the short circuit currents on both sides of the line are provided by a modular multilevel matrix converter. The phase angle of the short circuit currents on both sides is controlled and the amplitude is equivalent，resulting in a serious decrease in the sensitivity of differential protection. The characteristics of equivalent positive- and negative-sequence impedances on the voltage control side and power control side of low frequency transmission system are analyzed. It points out that due to different control strategies，there are significant differences in the characteristics of equivalent positive- and negative-sequence impedances on both sides of the system during faults. Then，the difference and similarity between the equivalent sequence impedances measured by the protection relays on both sides of the LFTL under internal and external faults are analyzed. Based on these features，an indicator for the difference of equivalent sequence impedances on both sides is constructed. A method for optimizing the braking coefficient of differential protection using the indicator is proposed. The simulative results show that the proposed scheme can significantly improve the operation speed and sensitivity of differential protection in case of faults in the LFTL area. © 2024 Electric Power Automation Equipment Press. All rights reserved.

引用

页码：143 / 150

页数：7

共 21 条

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