date：2021-10-28
author：Black
Introduction
The department of Electric Power System (EPS) currently has 20 faculty members, including 7 professors (among which Prof. He Jinghan is an IEEE Fellow) and 10 associate professors. In the last five years, the department has undertaken 10 projects funded by the National Natural Science Foundation of China, 13 national key R&D programs of "Smart Grid Technology and Equipment", and over 50 projects funded by State Grid and other companies. With a series of scientific research projects, the EPS department has developed rapidly, especially on the research of protective relays, power system resilience, AC/DC hybrid power systems, integrated energy systems and applications of artificial intelligence in power systems. The EPS department has gained many distinguished and innovative scientific research achievements and has built reputations and influence in China and abroad.
The department of Electric Power System has a comprehensive software and hardware experiment and testing platform. At present, it has a hardware-in-the-loop simulation platform of active distribution network systems including a 4-terminal flexible DC grid, a real-time digital simulation platform of power systems (RTDS, RT-LAB), and a simulation laboratory of power systems (DDRTS, BPA, PSASP, etc.). As a major contributor, the department got the approval and established the "National Active Distribution Network Technology Research Center" in 2013, and the center for innovation and intelligence of "Big Data Analysis and Processing of Active Distribution Network" in 2014.
The department of Electric Power System has about 70 Ph.D. and master's graduates every year, and they mainly work in State Grid or research institutes.
Research Directions
（1）Power system protection and resilience
The research works in relay protection are mainly about the distributed and centralized coordination of protection strategies, new protection algorithm based on information mining technology, low-frequency/low-voltage load reduction strategy, network structure restoration, etc. The resilience of power systems is about using relevant technologies of the distributed power sources to quickly recover critical loads while considering the coupling of key infrastructure systems, such as power grids, transportation networks, communication networks, water supply systems, and medical facilities, accurate allocation of limited power generation resource, and maximize the total social functions of the key power load recovered after the extreme events.
（2）Safe operation of AC-DC hybrid power systems
Based on the protection and control coordination concept, to balance the tradeoffs between the rapidity and reliability requirements of the protection system of hybrid HVDC systems, new theories and methods on fault identification and protection have been developed at the EPS department. The research considers the balance between the equipment protections on the location level and the transient stability emergency controls on the system level. It is aimed to break through the bottleneck in terms of fault analysis, DC protection theories, and preventing cascading failures.
（3）Integrated energy system planning, operation and control
Mainly study the complementary and alternative characteristics of multiple energy supply, including electricity, gas, heating, and cooling networks. consider the optimal dispatch strategy of demand response and game theory-based multi-agent market integrated energy system two-level planning technology, integrated energy system energy flow calculation method. Consider the dynamic response and self-healing methods of multiple energy complements.
（4）Application of artificial intelligence in power system
Artificial intelligence is the key supporting technology of smart energy. It has strong capability in terms of optimization and self-learning, to deal with high-dimensional, time-varying and nonlinear problems, and it can effectively overcome various challenges faced by the energy system. The deep integration of artificial intelligence and power system will be gradually realized by the combinations of intelligent sensing and physical state, data driving and simulation model, supportive decision-making and operation control, Improve the ability to control complex systems and improve the safety and economy of energy system operations.
Representative Results
（1）2019 Science and Technology Award of China Electrotechnical Society -- Research and application of key technologies for safe operation of complex distribution networks with heterogeneous multi-source and traffic loads
The project has been granted 18 invention patents, 1 utility model patent, and 3 design patents, with 45 SCI/EI papers being published. The project team has also organized and participated in the setting of 3 IEEE standards. The device and software developed have been successfully applied in many power grid enterprises and railway departments, which has improved the operational safety of distribution networks and generated significant economic and social benefits. The project has passed the achievements appraisal of China electrotechnical society. The appraisal committee whose chairmen are Yu Yixin and Luo An, members of the Chinese Academy of Engineering, agreed that the project has achieved multiple innovative results in the complex distribution network monitoring, protection and restoration with heterogeneous multi-source and traffic load. The whole project has reached the international leading level.
- In the aspect of monitoring, a multi-protocol and multi-interface intelligent measurement and control device suitable for flexible access of distributed power supply has been developed, and the hierarchical regulation of cluster power realized. A non-contact tension monitoring method of rail transit overhead lines based on the acceleration of falling weight and angular displacement of the ratchet wheels, and a temperature-data correction algorithm of overhead lines based on image retrieval have been proposed. An online monitoring device of rail transit overhead lines has also been developed to improve the accuracy of tension and temperature measurement. Because of the quantification of measured data, the influence mechanism of electric railway load harmonics and negative sequence casting upon the operation of adjacent new energy units has been revealed.
- In the aspect of protection, the EPS department proposed a calculation method of transient fault current based on step series approximation method considering the steel-rail skin effect, which has significantly improved the calculation accuracy; proposed new local protection algorithms such as amplitude ratio differential protection, wavelet transform DC feeder protection and isolated island detection method based on active power exchange; established a layered and distributed protection system of "local autonomy - station-region coordination - region-region coordination", and developed a protection control device for station-region integrated intelligent substation and an automatic system of intelligent traction substation based on IEC61850 standard, which realized a differential protection system covering the whole component and with self-adjusting range in distribution networks.
- In the aspect of restoration, we built a multi-source cooperative optimization model for distribution network restoration, proposed a fast algorithm for integer variable processing combining graph theory and convex relaxation technology for the use of solving the mixed-integer nonlinear programming model about failure restoration, and developed a multi-source cooperative optimization decision software for distribution network failure restoration; proposed an allocation strategy of mobile emergency resource and dynamic failure restoration method considering the coupling of "distribution network - traffic network"; designed a layered and distributed island control technology of the distribution network, which ensures the smooth implementation of the failure restoration strategy.
（2）Research on failure characteristics of hybrid cascade multi-terminal DC System and relay protection
Hybrid HVDC transmission system integrates the advantages of conventional HVDC system such as its high voltage, large capacity, technological reliability and the advantages of MMC-HVDC system. The system can effectively solve the problem of multi-HVDC feed-in in the receiving network in the future. Until now, there is no relevant research on design technology of failure clearance and recovery in hybrid cascade multi-terminal HVDC system in China or abroad. Under the future development trend and pattern of China's power grid, it is of key importance to study the failure characteristics of hybrid cascade multi-terminal HVDC power grid and the principle and technology of relay protection.
In the existing planning of power systems, the Baihetan-Jiangsu ±800kV HVDC transmission project will take the lead in applying hybrid cascade multi-terminal HVDC transmission technology. The protection design technology of hybrid HVDC systems studied by the Department of Electric Power System is not only the key technology that can ensure the safe and reliable operation of hybrid cascading multi-terminal HVDC systems, but also a current major challenge needed to be promptly solved in similar HVDC systems.
