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Trend of power electronics in micro grid, smart grid and smart community
CHEN Guo⁃cheng1,2, CAI Li⁃qing1, ZHOU Qin⁃li1, GU Hong⁃bing1, LEI Dian2
(1. Star Industrial Technology Co. Ltd., Changzhou 200122, China;
2. Department of Automation, Shanghai University, Shanghai 200072, China)
Abstract: In order to sustainably use energy and to protect the environment, the renewable energy is developed and
used around the globe. However, what problems will arise with the increasing portion of renewable energy connect⁃
ed to grid? How will the future energy landscape change? Countries are still exploring in this field. This paper is
based on the solutions of Fuji Electric, introduces new energy development and utilization, micro⁃grid, smart grid,
smart communities, energy management, communication networks, power stability, the balance of supply and de⁃
mand and other aspects of some of the vision of the company, and tries to explore the trend of the future of power e⁃
lectronics.
Key words: new energy; micro grid; smart grid; smart community; power electronics; EMS
Non⁃isolated Flyback⁃Boost converter with high gains
YUAN Yi⁃sheng, HU Pan⁃an, WU Qun⁃fang
(College of Electrical and Electronics Engineering, East China Jiaotong University, Nanchang 330013, China)
Abstract: A non⁃isolated converter with high gains consisting of a Flyback converter and a Boost converter is pro⁃
posed. The Flyback converter and the Boost converter share a power switch and an inductor. The output of the Fly⁃
back converter is in series with the output of the Boost converter. The energy of leakage inductance of the trans⁃
former of the Flyback converter can feedback into the output of the Boost converter. The proposed converter can a⁃
chieve high gains and high efficiency. Its advantages include simple construction and reduced voltage stress of pow⁃
er switch. The theory is analyzed, and the characteristic of voltage gains is derived. One prototype with 100kHz
switching frequency, 80W rated load, 24V input voltage and 200V output voltage, is tested. Its efficiency reaches
91 6% under 15W, and the test waveforms verify the theoretical analysis.
Key words: Flyback converter; Boost converter; high voltage gains; combined converter
Study on direct power control with constant switching frequency
based on space vector
LI Xin⁃zhe1, LIN Ming⁃yao1, FU Xing⁃he1, HAN Yu⁃zhuo2
(1. Engineering Research Center for Motion Control of Ministry of Education, Southeast University,
Nanjing 210096, China; 2. Suzhou Industrial Park Design & Research Institute Co. Ltd.,
Suzhou 215021, China)
Abstract: The direct power control (DPC) is a kind of effective control strategy of three⁃phase voltage⁃type PWM
rectifier, and the power inner of DPC is constituted by a switching table. The switching states are chosen by a
switching table depended on instantaneous power errors. In order to overcome the drawbacks of the unstable switch
frequency and unsatisfactory decoupling performance of active and reactive power of the traditional direct power con⁃
trol based on switching table, a novel DPC strategy of three⁃phase voltage⁃type PWM rectifier using space⁃vector
modulation (SVM) is proposed in this paper. The strategy, which is constituted by PI controllers and a modulation
by using SVW, has not only the advantages of simple algorithm, high power factor, rapid dynamic response and low
current harmonic compared with the traditional DPC, but also a stable switch frequency and lower sampling fre⁃
quency. These make the design of filter inductor easier. The simulation and experiment results confirm the validity
of this method.
Key words: PWM rectifier; direct power control (DPC); space vector modulation
Optimized design of high⁃efficiency AC motor external fan
by computational fluid dynamic method
LI Guang⁃yu, YUAN Li⁃qiang, ZHAO Zheng⁃ming, WANG Shu⁃ping
(State Key Lab of Control and Simulation of Power Systems and Generation Equipments,
Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: It is a challenge to further improve the efficiency of high⁃efficiency AC motors. One of the key is to re⁃
duce the loss of external fans and the traditional calculation method in terms of accuracy and applicability has been
unable to satisfy the requirements. This paper analyzes the external fan of YKK355⁃630 series high⁃voltage motors,
and compares the results with the traditional calculation method and computational fluid dynamics method. The re⁃
sults show that, as an effective way to optimize the high⁃efficiency AC motor fan and air duct, the application of
computational fluid dynamics has better applicability. At the end of this paper, the characteristic curves are given
and the analysis shows that it greatly reduces the fan losses and improves the efficiency of the motor.
Key words: high⁃efficiency AC motor; centrifugal fan; computational fluid dynamics; optimal design
Digital controller designing and optimization
based on new battery charger
LEI Jia⁃zhi1, 2, WANG Ke1, CHENG Yan3, LI Xun1, SUN Bo2
(1. College of Electrical and Electronic Engineering of Huazhong University of Science and Technology,
Wuhan 430074, China; 2. BIG POWER, Wuhan 430074, China; 3. College of Information Science
and Engineering, Wuhan University of Science and Technology, Wuhan 430074, China)
Abstract: Based on the energy storing system, this paper designed a new topology of a battery charger and intro⁃
duced the advantages of this topology. Based on the characteristics of the vanadium redox flow battery and the first
order RC model of the vanadium redox flow battery, this paper used small⁃signal model and the state space avera⁃
ging method to establish the battery system structure under constant current charging. A modeling method based on
VRB first order RC model of the DC⁃DC bi⁃directional converter was proposed. And then the parameter optimization
method of digital control system was used to design the controller of the DC⁃DC bi⁃directional converter. Finally,
based on VRB charging control strategy and VRB simulation model, simulation circuit was built in MATLAB and
2kW VRB charging experimental prototype was designed. Simulation and experiment results verified the correctness
of the design. Key words: battery charging circuit; first order RC model; parameter optimization
Selection of special frequency⁃band for transient based protection of
Yunnan⁃Guangdong UHVDC transmission line
CHEN Shi⁃long, XIE Jia⁃wei, BI Gui⁃hong, ZHANG Jie, SHU Hong⁃chun
(Faculty of Electrical Engineering, Kunming University of Science and Technology, Kunming 650050, China)
Abstract: The single⁃ended transient based voltage protection method of UHVDC transmission line which uses pro⁃
tector to distinguish the opposite inside fault from outside fault can protect the whole transmission line. Extracting the
special frequency⁃band of fault transient signals is important to the study of transient based protection of UHVDC
transmission line based on this theory. Accurate model of Yunnan⁃Guangdong ±800kV UHVDC Transmission System
is built up with reference to parameters of actual system. The stop band of refraction coefficient of transmission line
boundary has been obtained with reference to parameters of the boundary system. The main energy frequency band of
fault signals in stop band of refraction coefficient has been concluded by analyzing the frequency characteristics of
fault signals. And the special frequency⁃band in the main energy frequency is that corresponds to fault signals which
accords with the attenuation law that the attenuation effect from dual function of transmission line and its boundary is
stronger than that from single transmission line, and the fault location can be determined by using transient signals in
special frequency⁃band, so it can be extracted as fault signals in transient⁃based protection of transmission line.
Key words: UHVDC; transient⁃based protection; stop band of refraction coefficient; main energy frequency band;
special frequency⁃band
of grounding system using tunnel foundation in cable tunnel
DU Xue⁃long1, QIU Tian⁃jiao2, ZHANG Xiao⁃ying2, MA Xue⁃liang2, YIN Fan2, GUO Jian2, ZOU Jun1
(1. Department of Electrical Engineering, Tsinghua University, Beijing 100084, China;
2. Beijing Electric Power ECO INST, Beijing 100055, China)
Abstract: The grounding resistance is one of the important parameters for the safe operation of the grounding system
in cable tunnel. Based on the simulation analysis, a simplified formula for calculating the grounding resistance of
grounding system using the tunnel foundation (GSTF) is provided in this paper. Firstly, the simplified grounding
system of cable tunnel is obtained and the corresponding finite element simulation model is built. Then, the influ⁃
ence of the number of steel bar layer, the number of steel bar, the conductivity of cement layer and the thickness of
cement layer on the grounding resistance is analyzed. At last, according to the simulation results, the problem that
solving the grounding resistance of the complex grounding system in tunnel can be simplified to that solving the
grounding resistance of the buried cylindrical conductor whose grounding resistance can be obtained easily. The re⁃
sults indicate that the accuracy of the simplified formula can meet the needs of engineering calculation. And the ex⁃
pression is suitable for calculating the grounding resistance of GSTF in cable tunnel. Key words: cable tunnel; grounding system; grounding resistance
Study of reserve configuration of economic dispatch
in wind farm integrated system
MOU Chun⁃xiao1, LI Peng⁃bo1, YANG Jia⁃jun1, JIA Huan2, XU Jian⁃zheng1
(1. Shandong University, Jinan 250061, China;
2. Heze Power Company, Shandong Electric Power Group Corporation, Heze 274000, China)
Abstract: The uncertainty of wind power and load forecast brought difficulties to power economic dispatch, and the
problem need to be solved was how to deal with risk, economic generation and spinning reserve plan. The solution
which is economic and reliable is difficult to be attained by traditional ways. Load operating reserve capacity of the
system is mainly impacted by wind power prediction, so that the backup should be configured to cope with the un⁃
certainty of the system factors. Through the mutual check of the spare benefit and cost in the objective function,
suitable spare could be automatically configured for the system, and {0, 1} variable was introduced in the nonlin⁃
ear constraints, so it could be transformed to a group of linear constrains to express, and the transformation of the
mathematical model was a standard secondary mixed integer programming problem. The example results show the
effectiveness and practicability.
Key words: stochastic factor; spinning reserve; cost benefit; unit commitment; quadratic integer programming
Investigation of synchronous characteristic of laser
triggered gas switches
YIN Yi, YANG Jie, ZHONG Hui⁃huang, LIU Jin⁃liang, LI Zhi⁃qiang, HUANG Jun
(College of Opto⁃electric Science and Engineering, National University of
Defense Technology, Changsha 410073, China)
Abstract: Using the high voltage capacitor discharge gas switch test bed, the synchronous characteristics of two ni⁃
trogen filled laser triggered gas switches are experimentally investigated. The laser pulse with wavelength of 266 nm
and pulse width ~10 ns is used to trigger the gas switch. The results show that the delay time and jitter time of the
gas switch are both decreased as the laser energy increasing. As the percentage of self⁃breakdown voltage increas⁃
ing, the delay and jitter time are also decreased. At the laser energy 5 5 mJ, the jitter time of the single gas switch
breakdown voltage is at the range of sub⁃nanosecond, however, the difference of two delay times of the two switches
are greater than one nanosecond. At the laser energy of 8 8 mJ, the difference of two delay times of the two swit⁃
ches is at the range of sub⁃nanosecond; therefore the two switches can be regarded as synchronously operated.
Key words: delay time; jitter time; synchronous; laser triggered; gas switch
Study on harmonic distortion of voltage signal acquisition method
based on compressed sensing theory
TIAN Xiao, HE Jian⁃jun, YU Shou⁃yi
(School of Information Science and Engineering, Central South University, Changsha 410083, China)
Abstract: In view of the quick changing of power quality signal and large amount of data that need to be collected,
we discussed application of compressed sensing theory to power quality signal acquisition in this paper. Also we
demonstrated a new algorithm of constructing the rotation matrix according to the specific requirements for power
quality signal, which we called weighted observation matrix. Regulating the weight could lead to reconstruct accura⁃
cy change at different parts of signal independently. By adjusting the weight of different frequencies of signal ac⁃
cording to signal characteristics known in advance and specific requirement to the measurement, this new algorithm
has the ability to get more accurate reconstruction results of signal under higher compression ratio condition. The
performance of this algorithm was evaluated under different compression ratios. Compared with classical observation
matrix such as Gaussian random matrix and the traditional rotation matrix, our method demonstrated higher com⁃
pression ratio, higher reconstruction accuracy and better robustness. Key words: power quality; compressed sensing; observation matrix; rotation matrix
Research on IPT power supply in household application
WANG Chun⁃fang1, CHEN Jie⁃min1, LI Dan2, SUN Hui2
(1. School of Automation Engineering, Qingdao University, Qingdao 266071, China;
2. R & D Center of Haier Group, Qingdao 266103, China)
Abstract: In view of the disadvantages of the inductive power transfer, such as low efficiency and low power factor,
a novel IPT power supply in household application was designed in this paper. The main circuit of the power supply
contains three parts. They are the input switching network, the resonant coupling network and the high⁃frequency
rectifier network. The SP compensation method is adopted in the primary and secondary coil of the resonant cou⁃
pling network. The main circuit is analyzed and the equivalent circuit of the main circuit is obtained by using the
mutual inductance model method. The voltage gain is deduced to get the curves of the voltage gain changing with
resonant network parameters. A prototype of a 1000W power supply is implemented. To control the output voltage,
frequency look⁃up table fuzzy control method is adopted. The experiment of efficiency and power factor changing
with the primary and secondary coil is done. The experiment results verify the correctness and effectiveness of the
circuit design and control method.
Key words: household application; power supply; IPT; ZCS
Design and error analysis of transformer calibrator
MIAO Xin⁃fa, DU Li⁃xia
(School of Electronic and Information Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China)
Abstract: The transformer calibrator plays an important role in ensuring the successful application of the power sys⁃
tem. It is a common way to realize the transformer calibrator based on virtual instrument. At first, the hardware of
the calibrator composed of signal converter box, capture card and industrial computer is introduced. And then, the
accuracy of different algorithms which are affected by the fluctuations of the grid frequency is analyzed. At last,
when the frequency per cycle of the power grid is accurately attained, the FFT algorithm and the interpolation for⁃
mula are used to accurately test the amplitude and phase of the fundamental. The maximum amplitude error of the
algorithm is less than 0 013% and the maximum phase error does not exceed 0 3′. Key words: transformer; error analysis; FFT algorithm; interpolation algorithm; calibration
Ground fault protection schemes based on discriminant analysis
WANG Yuan⁃yuan, YUAN Jun, ZENG Xiang⁃jun, HUANG Yue
(Hunan Province Key Laboratory of Smart Grids Operation and Control,
Changsha University of Science and Technology, Changsha 410114, China)
Abstract: In order to improve the precision and reliability of traditional earth fault feeder detection schemes for
Neutral Ineffectively Earthed Power Systems (NIEPS), on the basis of the Mahal distance discriminant theory and
in combination with the project practice, a distance discriminant analysis model of earth fault feeder detection
scheme is established, in which five parameters are selected as the discrimination factor. The back substitution
method is introduced to verify the stability of the distance discriminant analysis model and the ratio of mistake⁃dis⁃
crimination is equal to zero after the distance discriminant analysis model was trained. By means of the model, oth⁃
er four groups of measured data are tested as testing sample, and the results are consistent with the measured data.
The simulation results show that the distance discriminant analysis model has a higher accuracy and low mis⁃dis⁃
crimination ratio.
Key words: distribution network; neutral ineffectively earthed power systems; earth fault feeder detection; dis⁃
criminant analysis
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