Department of Electric Power System

       Department of Electric Power System is mainly responsible for teaching and research tasks of the power system. Currently it has 5 professors, 6 associate professors and 5 lecturers. It enrolls doctoral students and graduate students in electrical engineering disciplines.
       Department of Electric Power System in the past five years led 2 National Natural Science Foundation key projects, one surface project; one national 973 project, 2 National 863 Project, 2 national scientific and technological support key projects, 4 key projects of the Ministry of Railways. The department also acquired 10 national invention patents and more than 20 provincial and ministerial level scientific and technological progress awards.
I. International cooperation
1. Beijng Jiaotong University—ALSTOM Research Center; and Beijing Jiaotong University —ALSTOM Student Training Research Center 


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Figure 1. Celebration activity of the center

  • Areas of cooperation: protection and control of the smart grid; protection and control of rail transit power supply system
  • Mode of cooperation: project grants; students will be jointly trained and accomplish the research practice at ALSTOM located in the UK


2. Cooperation with GE globe R&D center in the research field of Smart Grid 

Figure 2. Professor Ningbin, president of BJTU met Dr. Kennan, director of the smart grid department of GE globe R&D center, at the company of professor Wu JunYong and Xia Mingchao of Electrical Engineering School; and Dr. Deng Xinhua, chief of university External Affaris Office 
II. Main research directions and results

  • Smart grid related research

(1)Integrated network of digital substation protection and control 
The smart-grid structure is more complicated nowadays, and the operational mode is more flexible, the disadvantage of device independence and information limits is becoming obvious, which may lead to increase the possibility of intertripping. So it’s necessary to utilize redundant information to strengthen the ability of real-time monitoring, estimate and control, it is also very important to use integrated information to enhance the system observability in normal condition and accuracy of protection. 
This project is a National Natural Science Foundation project. Based on digital substation, and computer and communications technology, this project did research of the substation equipment integrated protection, through information redundancy and information sharing, coordination and cooperation of protection functions of between different devices, it optimized the related control strategies to improve synthesis and integration capabilities of substation equipment protection performance. 
Based on the structure and protection configuration of real substation, accurate simulation model is built using the Real Time Digital Simulator (RTDS). At the same time, the integrated protection hardware platform is constructed which includes transducers, merging units, GOOSE switches, protection device and intelligent units. According to the IEC61850-9-2 communication protocol, transducers collected analog signals and data is sent to merging units and switches through optical-fiber Ethernet to achieve sharing. Protection equipments finish the calculation by using the redundant information and the final action will be done. In order to promote the combination property and integrated property of substation, the integrated protection provides platform of communication and data sharing. Meanwhile, taking full advantages of the large sum of information is helpful to research new algorithms and control schemes of multiple apparatuses.
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Figure 3. Digital substation and digital protection research platform
 

 

 

 

 

 

 


Figure 4.  Scheme of Integrated network-based digital substation protection

(2)Protection system electromagnetic transient (PSCAD/EMTDC) model of UHV DC transmission (±800kV)

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For the construction of Ultra-High Voltage (UHV) power grid, based on the PSCAD/EMTDC, this project is to construct PSCAD / EMTDC equivalent model used in ± 800kV UHV DC transmission system to simulate equivalently current DC protection system and carry out characteristics research. Construct equivalent model of ± 800kV UHV DC transmission primary system in PSCAD / EMTDC platform,  to achieve signal acquisition and transmission of control signals  of the primary system in the PSCAD / EMTDC platform; 
Construct PSCAD / EMTDC interface with DC system protection function for engineering, use external function library to multiplex the DC system protection code for engineering in order to achieve equivalent protection simulation; construct time equivalent mechanism between the PSCAD / EMTDC offline simulation system and DC protection system for engineering to achieve equivalent simulation of real-time systems; conduct typical failure experiments to simulate equivalently in real-time ± 800kV UHV DC transmission protection function, do the research of protection features and action situations, inspect and determine the protection configurations and check rating parameters in engineering, suggest improvement and optimization plans, and provide technical support for engineering debug and operation. 
(3)Power quality on-line monitoring and management system
Multi-function on-line monitoring and management system for power quality mainly consists of the power monitoring center, Ethernet and the monitoring units in substations which is a hierarchical, distributed system. The monitoring units get the fundamental power parameters and the power quality indicators in substations and send them to the power monitoring center via Ethernet. The monitoring center analyze and process the data from monitoring units, and generate report forms and curves to have a complete knowledge of the power quality of power system so that it can provide the basis for improving power quality.

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Figure 7.  Power quality project cooperated with the Beijing Energy Saving and Power Technology Foundation 

Figure 8. Online power quality monitoring devices and on-site operation data

(4)Complex multi-branch distribution network online fault location research
The project belongs to one of the smart grid international communication series projects carried out in collaboration with the General Electric GE (China) R & D center. Addressing the complex multi-branch distribution network, with unbalanced three-phase load, mixed deposit and load volatility characteristics of overhead lines and underground cables, this project propose a recursive type segmented flow calculation method, it is just needs the information of the first segment of the distribution network feeder before and during the fault to quickly and accurately online search for the fault location. The method has high accuracy and strong robustness, especially for complex distribution network online fault location, and establish a solid theoretical foundation for the self-healing control of the smart grid. 

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(5)Cascade topology of STATCOM and Its control strategy research


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With its unique modular structure, rapid reactive power response, characteristics of sub-phase equilibrium and control ability and harmonic elimination capacity, cascade STATCOM has been widely applied in the fields of group of wind power connected to the grid, electrified railway harmonic control, active and reactive power and voltage control of AC and DC hybrid system, etc. And it is one of the most active hot spots of FACTs research area since the beginning of the 21st century. This project carried out in-depth research from main circuit structure of the STATCOM, the modulation strategy, system-level control strategy, the soft Phase-Locked Loop(PLL) technology, startup mode, and other aspects; built a detailed model of STATCOM under the PSCAD environment, and proposed a direct current decoupling control and nonlinear control strategy, SHE specific harmonic elimination modulation strategy, improved soft PLL technology, three DC capacitor voltage balance control strategies, and self-motivation and additional charging circuit startup mode, etc. It has passed verification through simulation. Cooperated with enterprises, the department developed a 12MVar STATCOM industrial grade product.

2Interactive technology research of electric vehicles connected to grid (V2G)
Smart Grid emphasizes safe, reliable, cost-effective, clean,  environment protective, friendly interactive. Electric vehicles can be a distributed mobile energy storage unit in the grid. Interactive technology of electric vehicles to grid (V2G) refers to the two-way communication between electric vehicles and the grid to realize the energy conversion between electric vehicles and the grid under the control of it. It involves in research of large-scale interactive influence of V2G to the power grid.


Figure 11. Scheme of V2G system structure and control
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Figure 12. Research of influence of V2G to the grid

3. Research related with Condition monitoring of electrical equipment status

(1)  Circuit Breaker on-line monitoring system
Circuit Breaker on-line monitoring system has realized the data collection, storage, processing and display and statistics for recorded waves of 10 kV AC circuit breaker and 750V DC circuit breaker. It is composed of the communication program, data processing program, and the user interface program. It can monitor the mechanical vibration signals of the circuit breaker switching process, breaker switching coil current, breaker switching main loop current, control power supply voltage, power supply voltage of the energy storage motor, and the circuit breaker auxiliary contact state, thus to distinguish the breaker critical states of its remaining electricity life, breaker switching coil current continuous time, breaker switching coil current, breaker switching time, mechanical parts of the movement of the breaker, energy storage motor action situation, etc.


Figure 13.  Software hiberarchy 
(2) Power transformer condition maintenance system based on sonic information 
This project is to monitor the sound of power transformers in running time, and use audio characteristic to identify the operating conditions of power transformers through the relationship study of audio features corresponding to different conditions of the power transformer, and to find out individual and common characteristics corresponding to these states; and use these characteristics to do qualitative or quantitative assessment of the overall state of the power transformer to form condition examination based maintenance decisions or recommendations. Distinguished results can be used as a separate indicator of the power transformer operating status, and can also be used as a part of various power transformer state maintenance methods; with other exam results, the audio exam results can realize the condition  maintenance of the transformer. 

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4. Research related with traction power supply system

(1)New type DC rail transit power supply system protection and fault location

   
 
Figure 15. Scheme of DC rail transit system fault location

 

2Effect of the high-speed electrified railway to Henan power grid stability characteristics 
For studying the interaction of the Henan Power Grid and the Zhengzhou-Xi'an high-speed passenger dedicated line, using the methods of traction substation on-site measurement, modeling and simulation of transient stability calculations, relay protection calibration and other methods, the project did a comprehensive and systematic study from the static and transient aspects of the influence of the high-speed electrified railway to Henan power grid stability characteristics. According to the measured data, it calculated the electrified railway harmonics and negative sequence distribution in the grid, verified relay protection settings, greatly reduced the reliability of relay malfunction, improved stable operation level of the power system. The acceptance experts believed that this project as a whole was in the international advanced level; it was in the international leading level in traction substation transient stable modeling aspect. 
Based on this project, four EI papers and a scholarly treatise have been published; a patent and a software copyright have been applied; an enterprise standard has been issued. Overall it achieved fruitful research results. In 2011 it was named as the Science and Technology Progress Second Prize by the State Grid Corporation.


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(3)High-speed railway traction power supply system RAMS assessment theory and its application 
The project belongs to the National Natural Science Foundation project. The studied subjects of the project include reliability, availability, maintainability and safety assessment of the high-speed rail 27.5kV traction power supply system and 10kV power supply system; from the external power system, the project did many aspects of research including reliability assessment of high-speed rail power supply, the voltage level of traction substation connected to the power system, reliability assessment of the traction substation, reliability assessment of the catenary, multi-objective optimization of catenary periodic preventive maintenance strategy, the safety assessment for considering the traction power supply system in the extreme weather conditions, such as gale, ice covered and lightning; established a RAMS theoretical assessment system of high-speed railway power supply system, and applied research results to the reality of China's first passenger dedicated line of Beijing and Tianjin intercity. 
Based on this project, 18 papers have been published, including 8 EI indexed papers; and a scholarly treatise have been published in Science Press, and achieved the Publication Fund of National Science and Technology for academic works.


 
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(4) Fault location device based on traveling wave for the high-speed railway traction system 
This project combines the characteristics of the electric railway traction system fault, chose type A distance measurement method as the main method, and the type B and C distance measurement methods as supplementary ranging methods. In the algorithm, it selected third-order B-spline wavelet as the basic wavelet, according to wavelet transform singularity detection theory to locate the singular points, and put forward the concrete steps of using the traveling wave to measure catenary fault distance. 
The core portion of the device hardware mainly adopted DSP control board and ARM control panel, based on high-speed sampling, and the GPS synchronized clock to achieve the precise positioning of the traveling wave. The research results have been used in high-speed rail (especially passenger dedicated line) to measure catenary fault distance; it greatly improved the accuracy of fault location, shortened the distance measuring time, and it is essential to the exclusion of the catenary fault; the results have social and promotional value.


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(5)Contact net (catenary) safety state real- time monitoring and testing technology 
Contact net safety real- time monitoring system use the technology as hidden trouble testing which puts contact line break line as the core ,whose monitoring contain height of Clump fell ,the weight of contact wire tension, position of ratchet wheel , pulley deflection of Pulley and so on.; and it uses the platinum resistance sensor temperature measuring technology to monitor catenary temperature ; at the same time it uses methods such as Mining feature information extraction, classification and identification. Finally it realizes the contact network security monitoring and intelligent assessment and early warning system.
The system uses high-accuracy sensor to realize real-time data acquisition, and at the same time uses respective data acquisition and processing module to  analyze the data statistically  , and also uses GPRS module to upload data  to the upper machine. Through the management of Multiple terminals, collected data analysis and processing, we can  judge whether the contact line that in a anchor within the scope of the period is safe.

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Awards:
Modularization of major categories of electrical disciplines, serialization, and systematization ofresearch and practice for practice teaching system (direct); 2004, the Beijing Educational Teaching Achievement Second Prize;
Research and Practice of personnel training mode of electrical disciplines major category (direct); 2004, Beijing Jiaotong University Teaching Achievement First Prize;
Modularization, serialization, and systematization ofresearch and practice for practice teaching system (direct) 2004, Beijing Jiaotong University Teaching Achievement First Prize;
Integration of ideas and academic education, multidirectional  enhancement of graduate competitiveness (direct) 2008, Beijing Jiaotong University Teaching Achievement First Prize;
"Introduction to Electrical Engineering" National Elaborate textbook
"Introduction to Electrical Engineering" National Elaborate Course
"JD-1 type comprehensive insulation test equipment"; 2002, Science and Technology Progress Third Prize of Ministry of Railways;
" Complete sets of 10kV power line fault automatic processing equipment"; 2004,  Guizhou Province Science and Technology Progress Second Prize
"Traction substation on-line monitoring and management automation system ";2008, Science and Technology Progress Third Prize of the Ministry of Railways;
"Railway transformer substation abnormal overvoltage comprehensive management unit"; 2011, Science and Technology Progress Third Prize of the Ministry of Railways;
"Electric locomotives over-articulated phase overvoltage mechanism and protective measures" ; 2011, Science and Technology Progress Third Prize of the Ministry of Railways.