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Communication solution of travelling wave based fault feeder selection
technique in smart distribution substation
WANG Bin, NI Jiang, DONG Xin⁃zhou
(State Key Lab of Control and Simulation of Power Systems and Generation Equipments,
Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: Compared to the frequency wave signals, the traveling wave can not be influenced by system oscillation,
transition resistance, CT saturation and the neutral point operation mode, especially in the field of fault detection
and protection technology. However, traveling wave signal sampling tends to reach a rate of 500 to 1000 times the
sampling rate of frequency signal. For digital substation based on the process level network communication, if using
the entire transient traveling wave sampled data, the protection and control system performance can not be improved
and even the communication network will lead to a blocking traffic which affects the safety of the entire substation.
To solve this problem, this paper proceeding from the effective expression of traveling wave signal, puts forward to
the process level network communication requirements on traveling wave, and combines with the requirements of
traveling wave line selection in distribution substation, simulates and tests maximum wave band of traveling transi⁃
ent signal under the constraint of real⁃time data communication. This paper presents two different data processing
and communication solutions. This paper promotes the traveling wave popularization and application in digital sub⁃
station technology.
Key words: IEC61850; process level communication; traveling wave sharing; data preprocessing; merging unit
Research of two three⁃phase permanent magnet synchronous motors
drive system with five⁃leg voltage source inverter supply
GENG Qiang1, ZHANG Bi⁃jun2, SHI Ting⁃na2, GU Xin1
(1. Tianjin Key Laboratory of Advanced Technology of Electrical Engineering and Energy,
Tianjin Polytechnic University, Tianjin 300387, China;
2. School of Electrical Engineering and Automation, Tianjin University, Tianjin 300072, China)
Abstract: In this paper, half⁃period modulation strategy is used to control the speed of two motors independently
based on the five⁃leg voltage source inverter driving two permanent magnet synchronous motors control system.
Combined with d, q⁃axis mathematical model of two motors, deadbeat current controller are designed. Compared
with conventional PI controller, the next shot output value of deadbeat controller can be given as reference value di⁃
rectly to the amount of control, thereby the adjustment time of dynamic process is reduced. Simulation and experi⁃
mental results can verify the rapidity and effectiveness of deadbeat controller. Key words: five⁃leg⁃inverter; permanent magnet synchronous motor; half⁃period modulation; deadbeat controller
Analysis of overcurrent fault occurred when electric mining haul truck brakes
CHEN Guan⁃hua1, YUAN Li⁃qiang1, YANG Ri⁃long2, WANG Wen⁃sheng2, ZHAO Zheng⁃ming1
(1. State Key Lab of Control and Simulation of Power Systems and Generation Equipments,
Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;
2. Beijing Dongfeng Locomotive Electrical Factory, Beijing 100072, China)
Abstract: Huge electric mining haul trucks are widely used in mining industries, which greatly increases the effi⁃
ciency of ore transportation in mines. Overcurrent faults easily occur in the motor drive system when trucks brake in
high speed area. As the limit of hardware of the system, traditional debug method is no longer accessible. In this
paper, a new overcurrent fault analysis method based on reverse technology is proposed, which is to get the real⁃
time value of voltage space vector in the control program from the measured real⁃time inverter output voltage. In the
overcurrent fault case in this paper, this method is applied and it proves that the sudden drop of transient frequency
of voltage space vector causes overcurrent, which are because of the electromagnetic interference of speed feedback
signal after further analysis. Detailed solution is given to solve this problem. Experiment proves the effectiveness of
the solution.
Key words: high power motor drive; electric mining haul truck; overcurrent fault; reverse technology
Research on control method of FESS based DC UPS
LIU Wen⁃jun, TANG Xi⁃sheng, ZHOU Long, QI Zhi⁃ping
(Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: Flywheel energy storage system (FESS), which stores energy in a rotating mass, is a kind of mechanical
energy storage system. FESS is now considered a promising technology for many applications due to its significant
advantages versus batteries. In order to solve the voltage sag problem of DC load introduced by the grid voltage sym⁃
metric falling, this paper first presents the topology and control method of FESS based DC UPS. When the grid volt⁃
age is normal, the strategy based on an outer speed loop cascaded with an inner current loop is used. When the
grid voltage falls symmetrically, the strategy based on an external DC⁃bus voltage loop cascaded with an internal
current loop is used. Then a zero⁃pole offset order⁃reduction design method for inner current loop is proposed, while
the control parameters of outer speed and outer DC⁃bus voltage loops are designed through using the symmetric opti⁃
mum function equivalency method. And the stabilities of designed controllers are analyzed. This control method is
verified by simulation in Matlab/ Simulink. The simulation results indicate that this control method and the designed
controller parameters can control the flywheel motor’s operation mode accurately, stabilize the DC load voltage and
make voltage⁃sensitive DC load not affected by grid power interruption.
Key words: Flywheel Energy Storage System (FESS); DC uninterruptable power supply (DC UPS); charge and
discharge control; permanent magnet synchronous motor (PMSM)
Design and simulation of capacitor reusing mode for
hybrid energy storage pulsed⁃power supply
WEI Pei⁃yu1, LI Hai⁃tao1, ZHANG Xin⁃hui1, WANG Qin⁃bing2, SONG Chun⁃lei3
(1. School of Electrical and Electronic Engineering, Shandong University of Technology,
Zibo 255049, China; 2. Zibo Power Supply Company, Zibo 255000, China;
3. Gaoqing Power Supply Company, Zibo 256300, China)
Abstract: In the superconducting inductive⁃capacitive hybrid (meat⁃grinder) pulsed⁃power supply, the capaci⁃
tance of switched⁃capacitor was also required to increase when the ratio of inductors was increased. It will reduce
the volume advantage of superconducting magnetic energy storage. In the paper, the impacts of switched⁃capacitor
on a single module circuit working characteristics have been analyzed, and a method that multi⁃module meat⁃grinder
circuits share a switched⁃capacitor branch is proposed. In order to verify the method, this paper makes a simulation
study of three⁃module with synchronous discharge mode and delay discharge mode. The result shows that multi⁃
module meat⁃grinder circuits share a switched⁃capacitor branch is feasible. Both of the two discharge modes im⁃
prove the load current pulse markedly, however, synchronous discharge mode reduces the volume advantage of su⁃
perconducting magnetic energy storage further, while the delay time discharge mode can improve the advantages of
superconducting energy storage significantly.
Key words: pulsed power; superconducting magnetic energy storage (SMES); current pulse; multi⁃module
Research on energy transmission efficiency based on air⁃core
solenoid mutual inductance coupling
HAN Jian⁃hui1, ZHANG Wei2, ZHAO Li⁃zhi1
(1. No. 91404 Troop PLA, Qinhuangdao 066200, China;
2. Shandong Vanform High Energy Physics Technology Co. Ltd., Jinan 250000, China)
Abstract: According to the principle of wireless energy transmission technique, this paper studied a set of energy
coupling transmission system whose core component is air⁃core solenoid combination (mutual inductance cou⁃
pling). Through the experimental measurement to the energy transmission efficiency of 36 self⁃made mutual induct⁃
ance couplings, this paper studied the mutual inductance coupling composed of air⁃core solenoid of different specifi⁃
cations and structures, the energy transmission efficiency variations under different air gaps, as well as the impact
of capacitance compensation application by the primary and secondary windings of the mutual inductance coupling
on the energy transmission efficiency, aiming to reduce the volume and weight of the energy coupling transmission
system and strengthen its practical applicability. Analyzed the measurement data, this paper found a pair of air⁃core
solenoid combination with high energy transmission efficiency. The energy transmission efficiency of the mutual in⁃
ductance coupling consisted by this air⁃core solenoid combination reached 33 74% under 10mm air gap and
17 37% under 20mm air gap after its primary and secondary windings receiving the capacitance compensation. The
energy transmission system made by this coupling, when applied with additional +15V direct voltage, is measured
practically under 20mm air gap, showing an input power of 16 34W and an output power of 2 84W. The practical
output power was able to satisfy the need of small power electric equipments.
Key words: air⁃core solenoid; pipe diameter; winding method; air gap; efficiency
Electrical and magnetic field distributions in toroidal core
with circular cross section for high⁃frequency electronic circuits
TIAN Li, TIAN Ming⁃xing
(Institute of Automatic and Electrical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China)
Abstract: In order to study electrical and magnetic field distributions in toroidal core with circular cross section for
high⁃frequency electronic circuits, when it is encircled partly by coil and leakage flux can not be ignored, accord⁃
ing to magnetic flux continuity principle and mirror image method, electrical and magnetic field distributions in to⁃
roidal cores encircled by one coil are transformed into electrical and magnetic field distributions in the actual section
of an infinite long cores along which an infinite number of images are introduced. Based on Maxwell equations and
superposition principle, analytical solutions are derived for the electrical and magnetic field intensity, in which the
field variables are expressed as a single series in terms of Bessel functions and trigonometric functions. Two analyti⁃
cal solutions of eddy⁃current power loss are derived. One is based on electric field intensity and the other is based
on self impedance. Calculation results agree with each other, and it validates the accuracy and validity of analytical
method. Calculation results of electrical and magnetic field intensity show that the conclusion of this paper can be
applied to the case of magnetic permeability of core being very high or the core being encircled tightly and uniformly
by coil, in which leakage flux can be ignored.
Key words: toroidal cores; electrical and magnetic field distributions; analytical solution; Bessel function
Research of sliding electric contact current receiving efficiency
in pantograph⁃catenary system
GUO Feng⁃yi, ZHANG Xiao⁃xiao
(Faculty of Electrical and Control Engineering, Liaoning Technical University, Huludao 125105, China)
Abstract: By using the design of sliding electrical contact friction and wear testing machine, a lot of experiments
were carried out to the copper tin alloy wire/ leaching copper carbon slide under different speed, current and pres⁃
sure conditions. Combined with the experimental data the curves of current receiving efficiency under different con⁃
ditions are drawn, and the theoretical analysis to the sliding speed, the current and contact pressure that affect the
current receiving efficiency is carried out. The conclusion is that the current receiving efficiency decreases as the
speed is gradually increasing, and when the velocity is small, the current receiving efficiency increases tremendous⁃
ly by the contact pressure. The current receiving efficiency increases with the increase of the current when the con⁃
tact pressure is between 30 ~80N, but when the contact pressure is between 80 ~120N, the current receiving re⁃
ceiving efficiency decreases as the current increases, and the current receiving efficiency increases as the contact
pressure increases in the overall trend. The larger the contact pressure and the given current are, the better the cur⁃
rent receiving efficiency is,and when the speed increases, the influence of the current receiving efficiency reduces
with the current, and speed becomes the main factor.
Key words: sliding electrical contact; current receiving efficiency; speed; current; contact pressure
High voltage withstanding study of high voltage contact fiber⁃optic insulator
WANG Min⁃ji, LI Chuan, ZHANG Xu, XIONG Xin, ZHAO Zhen⁃gang, XIE Tao, LI Ying⁃na
(Faculty of Information Engineering and Automation, Kunming University
of Science and Technology, Kunming 650500, China)
Abstract: In the case of pollution and dewing, power frequency and lightning overvoltage will cause electrical acci⁃
dents to the secondary components installed in electrical equipment. By using the silicone rubber hydrophobic mate⁃
rial and the structure mode of integral mold, we develop a high voltage contact fiber⁃optic insulator. The high volt⁃
age contact fiber⁃optic insulator has some features that a single or some covers which are used to cover the insulator
cover the fiber⁃optic’s surface. Besides, a sensing device is welded at the top of the fiber⁃optic and a fiber⁃optic
connector is installed at tail of the fiber⁃optic. Using of the fiber⁃optic insulator increases the creep distance of the
structure. The fiber⁃optic insulator was tested by the AC 15kV high voltage in the pollution⁃free, dew and pollution
environment. The tests showed that the high voltage contact fiber⁃optic insulator can be used for 15kV high voltage
environment.
Key words: fiber; silicone rubber; fiber⁃optic insulator; voltage test; creep distance
Robust current controller design method for DFIG
under unbalanced grid voltage
GONG Wen⁃ming1, 2, 3, HU Shu⁃ju2, 3, HUANG Wei⁃huang1, 2, 3, XU Hong⁃hua2, 3
(1. University of Chinese Academy of Sciences, Beijing 100190, China;
2. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
3. Key Laboratory of Wind Energy Utilization, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: In this paper, a current controller based on H∞ robust control theory is proposed, which can be used to
improve the performance of DFIGs under unbalanced grid voltage. First, the negative rotor current compensation
strategy is obtained in order to suppress the current distortion or power vibration with twice of the line frequency.
The design procedure of the H∞ current controller is presented, and the relationship between the performance re⁃
striction and the choice of weighting function is analyzed in detail. By conducting a μ analysis, the proposed H∞
controller is proved to have better robust stability against the parameter and operation point variation. Furthermore,
the H∞ controller is effective in restraining the stator oscillation mode, which decreases the transient process caused
by unbalanced grid voltage fault. The proposed control method is proved via simulation and experiments. Key words: wind energy; Doubly⁃Fed Induction Generator (DFIG); unbalanced grid voltage; H∞ robust control
Design and initial implementation of smart electric appliance network
ZHAO Xue⁃lin1, HE Guang⁃yu1, YANG Wen⁃xuan1, YU Nian⁃hong2, MO Guang⁃ling3
(1. State Key Lab of Control and Simulation of Power Systems and Generation Equipments,
Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;
2. Shanghai Qianguan Energy⁃saving Technology Co. Ltd., Shanghai 201706, China;
3. Guangzhou Electric Power Design Institute, Guangzhou 510610, China)
Abstract: Development of intelligent electricity is one of the important aspects of building the smart grid. Based on
previous concepts of intelligent electricity, smart home and automatic demand response, this paper presents the def⁃
inition of the smart electric appliance network. The smart electric appliance network is to form a network combined
of the user side’s all kinds of electrical appliances by the energy information gateway. It is aimed at building a net⁃
work based on the Internet of Things, the Internet and the smart grid technology with the massive electricity users.
The smart electricity network can not only help power consumers save energy and provide them with intelligent,
friendly, personalized and differentiated services, but can also guide power consumers to participate in the collabo⁃
rative demand response in a flexible interactive way to help achieve the optimal operation of the power grid. The
hardware part of the smart electric appliance network consists of the smart sockets, the smart infrared controllers,
the energy information gateways, the cloud servers, the mobile devices and other components. The software part of
the smart electric appliance network is developed on the Android platform. Currently, the smart electric appliance
network has been put into trial operation in Tsinghua ZiJing dormitory, and the results show that the proposed meth⁃
od is feasible and effective.
Key words: demand response; smart electric appliance network; smart sockets; energy saving
Analysis on optimization allocation of diesel for island microgrid
CHEN Rou⁃yi1, DONG Xu⁃zhu1, HUANG Shao⁃yuan1, LI Deng⁃wu2, CHEN Miao2
(1. Electric Power Research Institute, CSG, Guangzhou 510080, China;
2. Tianjin Tianda Qiushi Electric Power High Technology Co. Ltd. , Tianjin 300384, China)
Abstract: Microgrid is an efficient approach for taking advantage of renewable energy resources which can to a cer⁃
tain extent ensure reliability of the important load isolated from the power supply in island or remote area. How to
choose the model and confirm the capacity of the diesel generator as a primary energy support in an islanded micro⁃
grid has a direct impact on the reliability of power supply and on the economic performance of the system. Based on
an island microgrid system as an example, this paper puts forward a method to optimize the performance of diesel
generator. Simulation results show that the integrative performance using the optimizing configuration proposed is
excellent while taking the microgrid economic performance, the proportion of the renewable energy resources, pollu⁃
tant⁃emission and the diesel generator life into considering.
Key words: island microgrid; diesel generator; optimization allocation; energy saving and emission reduction
Research on wavelet de⁃noising scheme for field
overvoltage / lightning current signals
SHEN Yuan1, MA Yi1, WANG Lei1, LONG Yi2, YAO Chen⁃guo2, MI Yan2, WU Hao2
(1. Electric Power Research Institute of Yunnan Electric Power Test Research Institute (Group) Co. Ltd.,
Kunming 650217, China; 2. State Key Laboratory of Power Transmission Equipment & System Security
and New Technology, Chongqing University, Chongqing 400044, China)
Abstract: Overvoltage/ lightning current signals collected by field monitoring equipment contain very rich informa⁃
tion for fault types. However, the field waveforms are not all useful information, since the signals in the presence of
a large number of unavoidable white noise in various frequency bands, which have occupied part of the energy. In
order to guarantee and improve the monitoring equipment on accuracy of classification and recognition of field sig⁃
nals, before the overvoltage/ lightning current signal feature extraction, classification and recognition, the signals
must be preprocessed, which aims to eliminate the noise part that has no sense on or does harm to the classification
and recognition system of field signals. In this paper, currently popular de⁃noising method that is wavelet threshold
de⁃noising algorithm is applied to the field of overvoltage signals. Author compiles program based on wavelet algo⁃
rithm using Matlab software, and uses it to deal with simulation waveforms adding the noise signals, and then by
the assessing coefficient to reflect the effects of de⁃noising and reduction in various situations, therefore, the best
de⁃noising scheme of overvoltage/ lightning current signals is put forward. By combining the substation records with
this de⁃noising scheme, the effectiveness of the best de⁃noising scheme for overvoltage/ lightning current signals can
be proved.
Key words: wavelet threshold de⁃noising algorithm; Gaussian white noise; overvoltage/ lightning current signals;
assessing coefficients
Algorithm for substation active noise control
ZHAO Hong⁃fei1,2, MA Hong⁃zhong1, CHEN Kai3, WANG Chun⁃ning3, ZHONG Qin1
(1. College of Energy and Electrical Engineering, Hohai University, Nanjing 211100, China;
2. Yangzhou Department of Jiangsu Electric Power Company’s Maintenance Branch, Yangzhou 225000, China;
3. Nanjing Power Supply Company, Nanjing 210008, China)
Abstract: With the increase of city center substations and enhancement of people’s living environment require⁃
ments,noise nuisance and complaints from residents are becoming more severe. To address this issue, first of all,
we studied the substation noise characteristics, and found that larger frequency components of the substation noise
energy are mainly concentrated below 500Hz, and they are also integral multiples of 100Hz. These characteristic
signals are relatively stable over time, and will not be mutated. In the light of the deficiencies of traditional substa⁃
tion noise passive control method, this article presents an improved variable step size LMS adaptive filtering algo⁃
rithm combined with the adaptive active noise control technology. By simulating, we verify the performance of the
improved algorithm and process the measured data by using the improved algorithm. The results show that the noise
reduction algorithm can achieve satisfactory results. This article focuses on the substation noise signature and im⁃
provs the variable step size LMS adaptive filtering algorithm.
Key words: transformer noise; convergence rate; convergence precision; improved variable step size
Safety situation assessment model of power enterprise
based on human factor
QU Zhao⁃yang1, LIU Jiao1, REN You⁃xue2, FU Hao2
(1. College of Information Engineering, Northeast Dianli University, Jilin 132012, China;
2. Jilin Electric Power Company Limited, Jilin Electric Power Company, Jilin 132000, China)
Abstract: In view of the present situation that the power enterprise production accident is mainly caused by human
factors, a safety situation assessment model of the power enterprise based on human factor is proposed to provide a
reference basis for the power enterprise’s safety production management. Firstly, using the method of data statistics
and expert advice, the human factor evaluation index system with marking criterion is designed. Based on the im⁃
proved fuzzy analytical hierarchy process, the fuzzy judgment matrix and weight coefficient of every index are estab⁃
lished. Then, according to the result set and membership function, the electric power enterprise safety grade is e⁃
valuated comprehensively. Finally, the paper tests and verifies the high efficiency of the model by processing actual
data from a power enterprise and assessing the safety situation. The model is applicable for the power enterprise
safety situation assessment, which is based on human factors. The model could also predict the enterprise security
through the security membership value.
Key words: human factor; fuzzy analytical hierarchy process; security situation assessment; power enterprise
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