A. Abbasi, A. Hoang, P. Bergelin, E. Eriksson, F. Falth, “Performance evaluation of 525 kV and 640 kV extruded DC cable systems,” 10th International Conference on Insulated Power Cables, A9-4, 2019.

K. C. Ko, H. J. Joo, H. D. Hwang, B. S. Kim, S. K. Cho, “Study on Optimal Design of High-Voltage FGM Spacers Using Functionally Graded Materials,” Technology Development Project by the Ministry of Knowledge Economy of Korea, pp. 1-5, 2010.

Rachmawati, H. Kojima, K. Kato, N. Zebouchi, and N. Hayakawa, “Electric Field Grading and Discharge Inception Voltage Improvement on HVDC GIS/GIL Spacer With Permittivity and Conductivity Graded Materials (ε/σ-FGM),” IEEE Transactions on Dielectrics and Electrical Insulation, vol. 29, Issue 5, pp. 1811-1817, Oct. 2022. DOI:10.1109/TDEI.2022.3194489

Miyaji Yoshitaka, Kojima Hiroki, Kato Kazuhiko, Hayakawa Naoki, “Fabrication of GIS Spacer Model with ε-FGM (Functionally Graded Materials) and Theoretical Estimation of its Breakdown Voltage in SF6 Gas,” IEEJ Transactions on Fundamentals and Materials, vol, 138, pp. 155-162, 2018. DOI:10.1541/ieejfms.138.155

Yu-Min Kim, Myungchin Kim, “A Study on Nonlinear Resistance Measurement Techniques for Advanced Electric Field Analysis Technology for High Voltage Motor Coils,” The 52th KIEE Summer Conference, pp. 264-265, 2021.

Y. M. Kim, and M. Kim, “Stress Grading Performance Analysis of Stator Coil Considering the Manufacturing Method and the Insulation Design,” in IEEE Access, vol. 10, pp. 76493-76503, 2022. DOI: 10.1109/ACCESS.2022.3192626

M. Jeroense, “Fully qualified 640kV underground extruded DC cable system,” CIGRE Session 47, B1-309, pp. 1-11, 2018.

E. H. Jung, S. Y. Jung, “Development of HVDC 525kV GIS cable terminations,” The 55th KIEE Summer Conference, pp. 1951-1952, 2024.

S. M. Kang et al., “Study on the electrical and physical characteristics of ZnO varistor according to the sintering temperature,” 2014 International Conference on Lightning Protection (ICLP), Shanghai, China, pp. 1143-1146, 2014. DOI: 10.1109/ICLP.2014.6973298

S. K. Choi, “A Study on the Composition and Ceramic Process for Enhancing the Energy Capacity of ZnO Varistors,” Ph.D. Dissertation, Pusan National University, pp. 13-14, 2018.

Rashid Hussain, Christian Andersson, “Electrothermal FEM simulation of relevant test conditions of a 525 kV HVDC cable joint including nonlinear field grading material,” 11th International Conference Paper, Jicable, A1-2, 2023.

WG B1., “Recommendations for Testing DC Extruded Cable Systems for Power Transmission at a Rated Voltage up to and including 800 kV,” Cigre Technical Broshure 852, WG B1.62, pp. 1-95, 2021.

Thi Thu Nga Vu, Gilbert Teyssedre and Séverine LeRoy, “Electric Field Distribution in HVDC Cable Joint in Non-Stationary Conditions,” Energies, vol. 14, Issue 17, pp 1-17, 2021. DOI:10.3390/en14175401

Jiming Chen, Ying Gao, Mingxiao Zhu, Jiacai Li and Qianyu Yu, “Space Charge Dynamics in Double-layered Insulation Cable under Polarity Reversal Voltage,” IEEE Transactions on Dielectrics and Electrical Insulation, vol. 27, Issue 2, pp. 622-630, 2020. DOI: 10.1109/TDEI.2019.008457

T. Christen, L. Donzel, and F. Greuter, “Nonlinear resistive electric field grading part 1: Theory and simulation,” in IEEE Electrical Insulation Magazine, vol. 26, Issue 6, pp. 47-59, 2010. DOI: 10.1109/MEI.2010.5599979

Guimin Jiang, Yuanxiang Zhou, Chenyuan Teng, Yunxiao Zhang, Xin Huang, “Synergistic improved electrical resistivity-temperature characteristics and DC breakdown strength in insulating XLPE composites by incorporating positive temperature coefficient particles,” Polymer Testing, vol. 117, pp. 1-8, 2023. DOI:10.1016/j.polymertesting.2022.107839

Dong Li, Zhien Zhu, Liming Yang, Yili Ma, “Research on Nonlinear EPDM for ±525kV HVDC Cable Accessories,” MATEC Web of Conferences, vol. 260, pp. 1-5, 2019. DOI:10.1051/matecconf/201926002001