On the morning of October 21, 2025, Professor Oriol Gomis-Bellmunt, a renowned scholar and IEEE Fellow from the Polytechnic University of Catalonia (UPC), Spain, together with his wife, visited Tianjin University upon invitation. They toured the National Key Laboratory of Intelligent Power Transmission and Distribution Equipment and Systems and carried out academic exchange activities. The Tianjin University Smart Grid Protection and Control Team and Professor Oriol’s delegation held in-depth discussions and exchanges on frontier topics such as flexible DC grid protection and control and power-electronics-dominated power systems.
At the beginning of the exchange, Dr. He Jiawei delivered a presentation titled “Research and Development of Protection and Fault Current Limiting Technologies for Flexible DC Grids.” He systematically introduced the team’s theoretical research and engineering practice progress in this field. The report covered research background, technological innovations, and achievement transformation, highlighting several innovative solutions proposed by the research group, including single-ended transient energy protection, fast time-domain current differential protection, and a transient adaptive DC fault current limiter. Based on these theoretical achievements, the team collaborated with leading enterprises such as NR Electric and Beijing Sifang to successfully develop key equipment including a flexible DC line transient quantity protection device and the world’s first 200 kV adaptive DC fault current limiter. These technologies have been successfully applied in major national projects such as the Zhangbei Flexible DC Grid, Wudongde UHVDC Project, and Zhoushan Multi-terminal DC Project, effectively ensuring the safe and reliable operation of flexible DC systems.
After the presentation, Professor Oriol and his delegation visited the laboratory’s Hardware-in-the-Loop (HIL) experimental testing system for AC/DC grid protection and control, independently developed by Tianjin University. This system can accurately simulate various typical operating scenarios and fault characteristics of new power systems, providing a comprehensive verification platform for testing protection and control devices. Team members demonstrated two self-developed devices on-site — a DC line transient directional pilot protection device and a fast time-domain distance protection device for renewable energy grid-connected lines. Professor Oriol highly praised the team’s innovative achievements in “rapid fault identification–secure fault ride-through–reliable recovery” for DC systems, remarking: “The Tianjin University team’s innovations in flexible DC protection and fault ride-through are world-class. Their systematic achievements from theoretical research to product development and engineering application are truly admirable.”
During the afternoon expert report session, Dean Tan Chao delivered a welcome speech, warmly greeting Professor Oriol and his delegation. Professor Oriol then gave an insightful presentation titled “Power Electronic Dominated Power Systems: Challenges and Research Directions.” He comprehensively introduced his team’s latest research progress in the field of modern power systems, covering the group’s background, core research areas, and future prospects. The CITCEA-UPC research center, founded in 2001 and affiliated with the TECNIO network, currently has over 70 members, has completed more than 200 research projects, published over 300 high-level journal papers, and successfully incubated two spin-off companies — TeknoCEA and eRoots.
In his report, Professor Oriol analyzed the key challenges faced by power systems under high penetration of power electronics, such as insufficient system inertia, increased stability issues, and complex fault characteristics. He focused on introducing the latest control strategies for grid-forming and grid-following converters, modal analysis methods for system stability, short-circuit current calculation techniques based on full-scenario traversal, and grid equivalent modeling methods adapted to converter characteristics. He further proposed the new concept of a “Grid of Grids,” emphasizing that in future hybrid AC/DC systems, interconnected converters will serve as crucial elements supporting system stability and resilience, offering new insights for achieving the friendly integration of high shares of renewable energy. During the session, students and faculty actively engaged with questions, and Professor Oriol provided detailed answers, creating a warm and enthusiastic atmosphere.
After the meeting, Professor Oriol and his delegation visited the Tianjin Electric Power Research Institute for further exchange and discussion.
This visit not only deepened the academic collaboration between Tianjin University and UPC in the fields of flexible DC grids and renewable energy systems, but also laid a solid foundation for further cooperation in scientific research, student training, and international academic exchange.
