In order to promote scientific and technological progress in the field of electrical engineeringin China, encourage innovative research, and promote the growth of young professionals, the China Electrotechnical Societylaunched therecommendation and selection of outstanding doctoralpapers for the first time this year. Winners must have made important achievements in basic theories or applied basic research in electrical engineering and related fields during their PhD degree period, or have made significant achievements in key technologies or applied technology innovations.

s of the deadline, 36 doctoralpapers were received. After three stages of qualification review, preliminaryassessment and conferenceassessment, 5 outstanding doctoralpapers were finally selected from 10nominated papers. Zhang Xiangyu, a PhD graduated fromthe Department of Electrical Engineering, won the award forExcellent DoctoralPaperof the China Electrotechnical Society in 2021.

Winner:

Zhang Xiangyu, male,wasborn in November 1992. In 2015 and 2020. He received a bachelor’s degree and aPh. doctor’s degree from the Department of Electrical Engineering and Applied Electronics, Tsinghua University, respectively.He is now working in the School of Electrical and Electronic Engineering, North China Electric Power University, and is mainly engaged in the research of DC circuit breakers and high-power power electronic switches. The DC circuit breakers developedby him as a major member areused in the world first 500kV flexible DC power grid. He presided over 1 China Youth Project of theNational Natural Science Foundation,1 projectspecially funded by the Postdoctoral Science Foundation,1generalproject of the PostdoctoralScienceFoundation, 1project of the State KeyResearch andDevelopmentPlan andvarioushorizontal projects.He has published 11papers on theSCI journal as the first/corresponding author.He has also wonvariousawards, such as the Excellent Doctoral Student Graduated fromTsinghua University and Excellent Doctoral Paper, etc.

Award-winning paper:

Paper Title: Research on Key Technology of HVDC Hybrid Circuit Breaker

Engineering products of the500kV DCcircuitbreaker

Research background /Subjectsignificance / research value: DC transmission technology, withmany advantages that AC power grids do not have in terms of stability and transmission efficiency, has an indispensable position in the future energy Internet. However, since there is no current zero-crossing point in DC,it’s difficult to cut off the fault currentin any conventional wayafter a short circuit, making fault clearing a core problem that restricts the development of DC technology. Therefore,theresearch on high-voltage and large-current DC circuit breakers that can achieve millisecond-level interruption of tens of thousands of amperes of current andtolerance ofmegavolt voltage is the key to building an advanced DC grid in the future.

Main research content:Oriented to the needsfor fault clearing in high-voltage DC power grids,andovercoming the performance bottleneck and cost problem of current hybrid circuit breakers,the paper has successively proposedvarious innovative solutions including amodular series equalization method,across-bridge bidirectional unit topology andahybrid power electronicsswitch, andinitially constructed the theory and technical system of DC high-current ultra-fast breaking.Based on theoretical research results, the 500kV DC circuit breaker with the highest voltage and current levelso farhas been successfully developed and applied in the world first 500kV flexible DCgrid project, which isa new breakthrough in the field ofadvanced power equipment inChina.