A novel directional relay for AC lines close to the HVDC installation. (June 2020)

• Record Type: Journal Article
• Authors: Wang, Xingzhu; Wen, Minghao; Zheng, Junchao; Chen, Yongxin; Qin, Yu; Ma, Yahui
• Is Part Of: International journal of electrical power & energy systems. Volume 118(2020)
• Publication Date: 2020-06
• Subjects: HVDC transmission system -- Directional relay -- Correlation coefficient; Electrical engineering -- Periodicals; Electric power systems -- Periodicals; Électrotechnique -- Périodiques; Réseaux électriques (Énergie) -- Périodiques; Electric power systems; Electrical engineering; Periodicals; 621.3
• DOI: 10.1016/j.ijepes.2019.105726
• Languages: English
• ISSNs: 0142-0615

Abstract

Highlights: Compared with traditional distance protection based on fundamental components, the R-L differential-equation algorithm in time domain is more appropriate for the AC lines close to the HVDC installation. However, there exists a problem of voltage dead zone. There is a significant difference of the fault currents provided by the DC side and AC side. The former is non-sinusoidal, while the latter one has obvious sinusoidal characteristics. Low voltage component is used to differentiate whether the fault point is located in dead zone. Forward and reverse faults on the outlets of the AC lines can be identified based on the correlation of the measured voltage drop and calculated voltage drop. Extensive simulation results demonstrate that the proposed directional relay can detect fault direction accurately. It's also not affected by inverter status, fault types, and operation conditions of the receiving-end AC system. Abstract: Compared with traditional distance protection based on fundamental components, the R-L differential-equation algorithm in time domain, which is free of eliminating aperiodic component and insensitive to grid frequency, is more suitable for the AC lines close to high voltage direct current (HVDC) installation. However, there is a problem of voltage dead zone which occurs when the R-L differential equation algorithm is directly applied on the AC lines. According to the difference between fault currents' characteristics provided by direct current (DC) system and receiving-end AC system, then forward and reverse faults on the outlets of AC lines can be identified based on the correlation of the measured voltage drop and calculated voltage drop. Therefore, a novel directional relay based on the correlation coefficient of voltage waveform (CCVW) and low voltage component is proposed. Finally, an extensive performance evaluation in PSCAD/EMTDC and MATLAB simulation verifies the effectiveness of the directional relay. Influencing factors and comparative analysis show that the directional relay has a high sensitivity, rapidity, and reliability.