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A proposal on vigorously strengthening safety consideration on offshore oil exploitation and on petroleum and natural gas storage and transportation on lands
YAN Lu-guang1,LU Qiang2,SONG Zhen-qi3, DAI Jin-xing4,LIU Guang-ding5，HOU Bao-rong6，SUN Zhen-chun7, JIANG Biao8,HUANG Chang-gang1,SHEN Chen2,TAN Zong-ying9,HU Guo-yi4, JIANG Wei10, LIU Feng-song11，XIE Guang-feng11, FENG Xia11,WANG You-hua12,WANG Jing6,HE Yu-fa10, LIU Xin6
（1. Institute of Electrical Engineering，Chinese Academy of Sciences，Beijing 100190，China；2.Tsinghua University，Beijing 100084，China；3. Shandong University of Science and Technology，Qingdao 266590，China；4. Research Institute of Petroleum Exploration ＆ Development，Beijing 100083，China；5. Institute of Geology and Geophysics，Chinese Academy of Sciences，Beijing 100029，China；6. Institute of Oceanology，Chinese Academy of Sciences，Qingdao 266071，China；7. Consultation Center，China National Petroleum Corporation，Beijing 100007，China；8. Shanghai Advanced Research Institute，Chinese Academy of Sciences，Shanghai 201210，China；9. National Science Library，Chinese Academy of Sciences，Beijing 100190，China；10. China National Offshore Oil Corp.，Beijing 100010，China；11. Academician Bureau of the Chinese Academy of Sciences,Beijing 100864，China；12. China National Petroleum Corporation,Beijing 100007，China）
Abstract：To guarantee the reliable and safe supply of petroleum and natural gas is the foundation of sustainable development in China. The safety consideration on offshore oil exploitation and on petroleum and natural gas storage and transportation on lands is one of important aspect of the energy development. In this paper the importance of safety consideration, the safety situation of offshore oil exploitation and safety situation of petroleum and natural gas storage and transportation, the related technologies of security were described. Also the main proposal was submitted.
Key words: safety on offshore oil developing；safety on petroleum and natural gas storage and transport on lands
Design of zero-phase digital filter with K factor used in parameters evaluation for lightning impulse
SI Wen-rong1, FU Chen-zhao1, HUANG Hua1, JIN Heng1, LI Yan-ming2
(1. Electric Power Research Institute. SMEPC, Shanghai 200437, China; 2. State Key Lab of
Elec. Insulation and Power Equipment (Xi’an Jiaotong University), Xi’an 710049, China)
Abstract: According to the procedures for calculation of parameters of standard lightning impulses with superimposed overshoot or oscillations in IEC 60060-1 Ed.3.0: High-voltage test techniques Part 1: General definitions and test requirements, and the introduced frequency dependent test voltage factor k(f), a way to design of zero-phase digital filter corresponding to the k(f) with IIR method is given in this paper. Principle of the Zero-phase digital filter is shown with simulation test using signal processing to sine wave. The difference equation with the same frequency characteristic as k(f) defined in IEC 60060-1 Ed.3.0, used to develop the software for measurement in impulse test is given. At last, the method is validated by processing several typical lightning impulses in TDG2.04 of IEC 61083-2 Ed.2.0: Instruments and software used for measurement in high-voltage impulse tests Part 2: requirements for software, which shows its feasibility and veracity. This provides an effective digital filtering technology to develop impulse test system.
Key words: test factor k(f); zero-phase; digital filtering; lightning impulse; parameters evaluation
Design & implementation of bidirectional non-dissipative battery balancing system
ZHANG Jin-long，XIA Chao-ying
(School of Electrical Engineering and Automation，Tianjin University，Tianjin 300072，China)
Abstract: To solve the un-uniformity problem of each cell voltage when the LiFePO4 batteries operate under series-connected condition, a bidirectional non-dissipative battery balancing system is designed and implemented. Signal processing circuit and balancing circuit are integrated through effective resource allocation; and a novel group-balancing strategy is designed to control the balancing process. It is confirmed by the experimental result that the voltage differences among the battery cells could be effectively restrained; also a fast balancing speed and a good balancing accuracy can be realized.
Key words: storage inductor; LiFePO4 battery; bidirectional balancing; group-balancing strategy
A large capacity 35KV reactive power compensation and harmonic suppression integrated system
SUN Juan1, LUO An1, SHUAI Zhi-kang1, ZHANG Jiu-lin2
(1. College of Elec. and Information Eng., Hunan University, Changsha 410082, China;
2. Chongqing Power Maintenance Branch Company, Chongqing 400020, China)
Abstract: In order to solve the power quality problems of harmonic and reactive power in a substation of Guangxi province, this paper proposes a large capacity 35KV reactive power compensation and harmonic suppression integrated system. The system adopts a set of single tuning passive filter connected with active inverter in series, as the inject branch of active inverter, and the active part connected with multiple single tuning passive filters in parallel to join up the power grid.The passive part compensates reactive power,while the passive and active part jointly restrain harmonics. Topological structure and compensation principle of the comprehensive system are analyzed, and a closed loop control strategy of voltage outer loop-current inner loop is presented to guarantee the stability of active power filter DC-side voltage and to realize functions of reactive power compensation and harmonic suppression.Moreover, protection measures for the passive filter and active power filter are adopted to ensure system safety. Operation result shows the effectiveness of the system.
Key word: reactive power compensation; harmonic suppression; closed loop control; system protection
Current density distribution characters of C-shaped armature in EML system
CAO Zhao-jun1,XIAO Zheng1,2
(1.State Grid Electric Power Research Institute, Wuhan 430074, China;2. College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)
Abstract：In order to realize the joule heat distribution characters in the process of electromagnetic launch, on the assumption of the nondisjunction and complete entire contact between the armature and rail, the inner current field distribution and the consequently temperature field distribution characters of C-shaped armature in the launching process were analyzed based on numerical simulation. Furthermore, the effects of the changes in C-shaped armature’s structure on the inner armature current field distribution and their working mechanism were discussed. Quasistatic magnetic and electric fields are applied to explain the distribution characteristic, and the results show that the skin effect and proximity effect have effects upon the distribution character of the armature. The maximum current density was decreased by the increase of the side thickness and front thickness, but the length of the armature had little effect on the maximum current density.
Keywords: electromagnetic launch; C-shaped armature; current density distribution; numerical simulation
Electro-thermal coupling computation of underground power cables
WANG Qiao-ling1, YANG Yu-ping2，LIANG Yong-chun3
(1. Inst. of Information Science & Eng., Hebei University of Science and Technology, Shijiazhuang 050018, China; 2. Polytechnic College, Hebei Univ. of Science and Technology, Shijiazhuang 050018, China;
3. Institute of Elec. Eng. & Information Tech., Hebei Univ. of Science and Technology, Shijiazhuang 050018, China )
Abstract: Finite element method (FEM) is used to calculate the Joule losses and temperature of underground cables. Iteration method is used to solve the electro-thermal coupling problem and to improve the accuracy of the calculation. Iteration method is also used to calculate the ampacity of underground cables. The temperature of underground multi-core cables is calculated in this paper and the ampacity is given out. The result of electro-thermal coupling method is more close to experimental result than that of non coupling method. This method is effective for engineering use.
Key words: electro-thermal coupling; finite element method; temperature distribution; ampacity
A new method with high accuracy for electrical harmonice estimation based on CZT
QIN Yuan-qian，TANG Yi，YANG Luo
(School of Information and Electrical Engineering, China University of Mining andTechnology, Xuzhou 221008，China)
Abstract: A new method with high accuracy for electrical harmonic estimation based on CZT(Chirp z-transform) is presented in this paper. First ,using the characteristic that CZT can realise frequency spectrum refinement, the phasor of the power system fundamental frequecy signals is extracted from the multifrequency signals. After subtracting the system fundamental frequecy signal from the multifrequency signals, the surplus signal is truncated with the the five term Rife-Vincent window and its spectrums are calculated by FFT .Finally,according to the power system fundamental frequecy, each harmonic frequency is calculated. And then the Rife-Vincent window is interpolated in the frequency domain. The results of experiments show that the five term Rife-Vincent window has a better curb ability to the spectral leakage. And in the non-coherent sampling conditions, the proposed method almost has the same estimation accuracy with the method which is based on multipoint Interpolation FFT through analysing the 30 order harmonics, but the new method only costs about half computation times.
Key words：harmonic analysis; CZT; FFT; Rife-Vincent window; interpolation in frequency domain
Dynamic modeling and analysis of thermoelectric equipment
YUAN Yi-sheng, XIONG Jing
(School of Electrical Engineering, East China Jiaotong University, Nanchang 330013, China)
Abstract: The mathematical model of the thermoelectric generator (TEG) equipment based on TEG device is built up. By applying the first law of thermodynamics, the dynamic mathematic model of the hot/cold side heatsink and the TEG are built up, and then the equivalent circuit model is derived. By simplifying some components with small thermo-capacitance, the completed dynamic equivalent circuit model is described. The source response of output voltage under input thermo-energy change and the load response of the output voltage under load resistor change are analyzed. One small experimental device is setup. The voltage waveforms under both source change and load change condition are recorded, which are same as the simulation waveforms. It proves that the model and analysis are available.
Key words: thermoelectric generator; mathematic model; equivalent circuit; dynamic response
Analysis and design of small grid inverter with filter
CHEN Xiao-yu，LUO Li-wen
(Shanghai Jiaotong University, State Energy Smart Grid R&D Center, Shanhai 200240 ,China)
Abstract: The output of grid inverter contains plenty of harmonics, when connected with grid will directly bring harmonic pollution to grid and is harmful to the tracing accuracy. In addition, there exists a zero-resistance band in the traditional LCL filter without damping resistance. On the basis of LCL without damping resistance, a kind of filter with damping resistance is designed and the mathematical model of filter is established to analysis the effect of resistance value on the filter effect and system efficiency. Through the Fourier analysis, a conclusion has been proved that the filter can reduce the THD of current waveform and improve the tracing accuracy.
Key words: inverter; filter; deadbeat; harmonics
Research on modulation method of five-leg inverter fed dual induction motor drive system
LIU Jia1, MEI Yang2, WANG Li-na1, SUN Kai3
(1.School of Automation Science and Elec. Eng., Beihang University, Beijing 100191, China;
2.Power Electronics & Motor Driving Eng. Center, North China University of Technology, Beijing 100041, China；
3.State Key Lab of Power Systems, Dept. of Elec. Eng., Tsinghua University, Beijing 100084, China)
Abstract: In electric trains, electric vehicles and some industry applications, two or more motors are needed to operate in parallel. Therefore, multiple inverters are needed in these drive systems. In order to reduce the system cost, a dual induction motor drive system fed by a five-leg inverter with independent control is investigated in this paper. An improved 7-section modulation method, which is based on the traditional Space Vector PWM (SVPWM) technology and which divides the control period into two parts, is proposed to control the five-leg inverter. This method is suitable to be implemented by DSP, which is its main advantage. Through simulation and experiments, the feasibility and effectiveness of the proposed method are proved.
Key words: five-leg inverter; modulation method; induction motor; SVPWM
Dead time and forward voltage compensation strategy of the three level inverter based on the current vector
SONG Wen-xiang, ZHANG Xu
(School of Mechanical & Electronic Engineering and Automation, Shanghai University ,Shanghai 200072, China)
Abstract: In order to prevent the output waveforms distortion due to dead-time and forward voltage, we must add the dead-time and forward voltage compensation in the process of motor control. This paper introduced a simple and efficient dead-time compensation method for three-level inverter to improve output waveforms. The cause of dead-time was analysed in detail, and dead-time can be compensated accurately using current vector. We analyse the changes in forward voltage of power devices based on PWM state and the position of current vector, and then compensate according to the current direction. Finally open and closed loop experiments are done to prove the proposed strategy through experiment on a three-level model inverter developed with F2812DSP. We can prove that the analysis is correct and the method can be used in practice.
Key words: three-level inverter; dead-time compensation; forward voltage compensation; current vector
Optimal control of DC voltage for active power filter
XU Feng1, Cheng Han-xiang2, HE Shao-yang2
(1. Electric and Electronic Department, Taizhou Vocational & Technical College, Taizhou 318000, China；
2. Faculty of Automation, Guangdong University of Technology, Guangzhou 510006, China)
Abstract: Firstly, this paper analyzes the DC side compensation voltage of APF fluctuation effect on the system and makes the relevant experiments. It shows that with better DC voltage control, the harmonic compensation system is more favorable. To encounter this problem, in the DC side two kinds of voltage control are applied. Through analysis of experimental results,optimized PI control mode can be obtained, and the system current compensation effect can be better.
Key words: harmonics；active power filter；optimal control；compensation effect
Research of single-phase grid-connected inverter based on improved current control strategy
ZENG Xiao-sheng, YANG Ping
（China School of Electric Power, South China University of Technology, Guangdong key laboratory of Clean Energy Technology, Guangzhou 510640, China）
Abstract: The performance of the single phase grid-connected inverter depends on mainly its control technique. The traditional single-loop PI control of instantaneous value of grid current can make the system to gain fast dynamic performance, but is not capable to obtain high amplitude accuracy of the output current and the system will be interfered with by the grid voltage. To solve the above problems, a double-loop strategy of the mean value and instantaneous value of grid-current is proposed in this paper. The inner loop of the instantaneous value makes the output current of the inverter tracking the sinusoidal reference current quickly, while the outer loop of the mean value makes the amplitude of the output current equal to the one of the reference. So the solution proposed in this paper can help to obtain high accuracy and to offset the impact of the grid voltage with its the feed forward loop. The simulation and prototype experiments had verified that the proposal is effective.
Key words: grid-connected inverter; current control; double-loop control; outer loop of mean value; feed forward of grid voltage
Static voltage stability analysis considering active power of transmission line constraints
CHU Zhuang，WANG Liang-liang，CAI Guo-wei
（School of Electrical Engineering，Northeast China Dianli University，Jilin 132012，China）
Abstract: In the process of calculating the critical point of voltage stability, power system of the static safe operational constraints such as active power of transmission line is considered. It converts the calculation of the critical point of voltage stability to a nonlinear programming problem, and the maximum loading margin mathematical model is established as the object function. The critical point of static voltage stability is found along a known load change direction in this paper by the nonlinear primal-dual interior point method which has less demand on the initial value. This method permits the efficient and effective handling of large sets of equality and inequality constraints, and has strong robustness. This paper compares the branch power in two cases of considering active power of transmission line constraints and not considering, then the weak branch could be found in power system. The approach proposed has been successfully tested on the IEEE-30 bus system.
Key words：voltage stability；loading margin；critical point；primal-dual interior point method；weak branch
A review on microgrid optimal operation
LIU Wen-sheng，MAO Xiao-ming，CHEN Zhi-yong
（Guangdong University of Technology, Faculty of Automation, Guangzhou 510006, China）
Abstract：Microgrid integrates different kinds of distributed generations, loads and energy-storage units. It can operate in interconnected mode or islanded mode as needed. It has the advantage to reduce power losses and improve service reliability. Optimizing microgrid operation is one of the key problems in concern. This paper gives a review on recent studies regarding microgrid optimal operation. The mathematical models dealing with cost optimization, reduction of the emission, maximization of profits and multi-objectives are first summarized. The optimizing algorithms used to solve the models, including genetic algorithm, differential evolution algorithm, bacterial foraging algorithm and particle swarm optimization are discussed together with the multi-objective optimization technologies. Finally, further research trends are explored based on the analysis of the existing study of deficiencies.
Key words：microgrid; optimal operation; economic dispatch
Magnetic modulation-based DC leakage current transformer
WANG Yao, LI Kui, GUO Zhi-tao, YUE Da-wei, NIU Feng
(Hebei University of Technology, Tianjin 300130, China)
Abstract：A magnetic modulation-based DC leakage current transformer (MM DC LCT) with single winding is presented to improve the shortcomings of complex structure and circuits of present MM DC LCT. A MCU-based MM DC LCT prototype is designed. And accuracy measurement is implemented via detecting dc component from output signals of secondary winding with simple circuit. Meanwhile, a RS485 communication interface is provided for users to implicate insulation monitoring system for DC system, thus digital measurement can be implemented. Finally, it is verified that the MM DC LCT prototype has good performance with low measurement of error less than 3%, which can meet the demand of insulation monitor for DC system.
Key words：magnetic modulation；insulation monitor for DC system；DC leakage current
Development of discone antenna used for detecting corona of electrical equipments
LIU Xiao-quan1, ZHOU Ze-hong1, CUI Yu-jia1, HUANG Hao1, ZHOU Mao1, YAO Chen-guo 2
(1. Chongqing Electric Power Company, Chongqing 400014, China; 2. State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China)
Abstract: For detecting corona discharge of electrical equipments within the substation, a wideband, high gain and horizontal plane omnidirectional antenna is researched for corona detecting sensor. Characteristic radiation and characteristic impedance of discone antenna is analyzed, and the result confirms that it is dominant to design a discone antenna as corona detecting antenna. The discone antenna with band from 10MHz to above 1GHz and average gain above 4dB is made via discrete method, and it shows good corona discharge signals detecting performance in substation measurement test. Fixed and mounted corona monitoring system can be developed based on this antenna, and the system can monitor corona levels of electrical equipments within substation, and it is noncontact with equipments during working conditions.
Key words: detecting; substation; electrical equipment; corona discharge; discone antenna
Application of GLBest-PSO algorithm for parameters identification of thermal process model
HAO Chao,XU Zhi-cheng
(Changzhou Institute of Mechatronic Technology, Jiangsu Changzhou 213164，China)
Abstract： The mathematical model of process object is of significance to the design and analysis of the thermal control system. For the purpose of achieving accurate model, an identification method based on particle swarm optimization algorithm combining the global-local best parameter is proposed. By taking every parameter of process model as a particle of the swarm and applying particles to search optimal parameters of process model concurrently and efficiently in the parameter space, the precision and efficiency of parameter identification are improved. The identification results for the typical thermal process show that the method is not sensitive to the order of the model, and can obtain satisfactory identification precision and efficiency for different input signal. The model outputs coincide with actual outputs. The identification method achieves good result.
Keywords: thermal process; particle swarm optimization; global-local best
An on-line monitoring system for EAF’s power quality data
TENG Zhi-jun1, WANG Zhong-bao1,ZHAO Long2,LI Guo-qiang1
（1.Department of Information Engineering, Northeast Dianli University,Jilin 132012,China;
2.Power Supply Company in Jinzhou, Jinzhou 121000,China）
Abstract：This paper briefly expounded the test method on EAF’s power quality, introduced ZigBee technology , designed and completed hardware and software of the system. Meanwhile, the author selected an EAF in a steel mill for EAF’s power quality data. The result of tests shows that monitoring system is simple and convenient when it was installed.The whole system has many advantages ,for instance, highly stability, good electromagnetic compatibility and high popularization value.
Key words: power quality; ZigBee;EAF;monitoring
Design of single phase grid-tied PV inverter
MAO Xing-kui, MAO Hong-sheng, PEI Chang-sheng,ZHANG Jin-ji
(College of Electrical Engineering and Automation, Fuzhou University, Fuzhou 350108, China)
Abstract：In view of wide range output voltage of PV cells, a single-phase PV grid-connected inverter solution with a quasi-two-stages circuit topology and dual-CPU controller was proposed. The Simulink simulation model for the inverter including PV model was established. In order to achieve MPPT in wide voltage range, MPPT was realized in the inverting power stage . The simulation and experiments showed that the 1.5kW prototype had good performance, and the novel improved P&O MPPT method with variable step would reduce oscillation during MPPT. Inverter filter inductance by interpolation with core AL vs. NI curve could meet requirement on high precision inductor model, and overcome the great variation of powder core inductance with inductor current change.
Key words: PV grid-connected inverter；MPPT；deadbeat control
Research on fast charger for electric bicycles
ZHU Shi-pan，WANG Chun-fang，ZHANG Zhi-yong
（School of Automation Engineering，Qingdao University，Qingdao 266071，China）
Abstract: Because there is no depolarization measures in the traditional way of charging batteries，it will affect the battery charging time，capacity and life time. In order to solve these problems， a constant voltage negative and positive current pulse output fast charger is designed. While this way of charging puts forward higher request for the stability to the switch converter，it is necessary to design a reasonable controller. The main circuit uses two-switch forward converter circuit. According to two conditions on continuous working model of forward circuit，a small-signal model is designed and based on Bode graph，a compensating network of the control circle is designed. Lastly，using Matlab to simulate the close loop transfer function and to test output negative and positive current wave by experiment，the rationality of this design is proved. This design can solve these problems of the fast charger for electric bicycles．
Key words: fast charger of electric bicycles；small-signal model；compensating network；two-switch forward converter
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