Research on differential protection of low frequency transmission lines based on differential principle of sampling values
- Resource Type
- article
- Authors
- PAN Wulue; QIAN Zhengxu; SUN Zhipan; HONG Feng; CAO Wenbin; WANG Song; FANG Yudong
- Source
- Zhejiang dianli, Vol 42, Iss 2, Pp 35-42 (2023)
- Subject
- low-frequency transmission
line protection
differential protection
sampling value differential
Electrical engineering. Electronics. Nuclear engineering
TK1-9971
- Language
- Chinese
- ISSN
- 1007-1881
As a fault occurs in a low-frequency transmission line zone, the modular multilevel matrix converters (M3Cs) at both ends of the line limit the fault current amplitude and phase. Under such a circumstance, the current on both sides displays the characteristics of through current, which in turn leads to poor sensitivity or even failure to operate of the traditional phase-based line differential protection. To solve the above problems, the electrical characteristics of the line after a fault and the adaptability of the phase differential protection are analyzed first based on the architecture of the low-frequency transmission system. Then three logical criteria based on the sampling values are given in combination with the differential principle of sampling values, which together with the steady-state differential threshold current and the low ratio braking equation constitute a differential protection method applicable to low-frequency transmission lines. Finally, a model of the low-frequency transmission system is built in RTDS (real-time digital simulation) system, and the effectiveness of the method used in low-frequency transmission lines is verified through the simulation analysis of different types of faults within and outside the lines, which lays the foundation for subsequent engineering applications.