Chen F.C.,Shenzhen Power Grid |
Song X.N.,Shanghai JiaoTong University |
Zhang B.,Shenzhen Power Grid |
Zhou R.L.,Shenzhen Power Grid
Applied Mechanics and Materials | Year: 2014
Because of the unsatisfied present situation of bidding evaluation in the field of electric power equipment, the LCC theory is introduced into the bidding evaluation method, which can be used to evaluate the total cost of electric power equipment. Combining with ADC method, the paper proposes a comprehensive procurement model and verifies it by a practical case. © (2014) Trans Tech Publications, Switzerland.
Yang J.,Tsinghua University |
Wu W.,Tsinghua University |
Sun H.,Tsinghua University |
Tao W.,Shenzhen Power Grid |
And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010
The traditional automatic switchover device installed in sub-station only uses local real-time information to make corresponding strategies, but the logic of device is predetermined, so it could only adapt to specific operating modes. A new wide-area automatic switchover system based on energy manage system (EMS) is proposed in the paper. The wide-area automatic switchover modeling is established in control center and the real-time restoration control is implemented. The system expands the automatic switchover functions and solves the power supply recovery under serial single power supply failure. In the process of getting information, formation of control strategies and performing control actions, by comprehensive use of information of the whole network, the automatic switchover can coordinate with other security and stability devices. In addition, the control strategies and network security will be checked and modified in order to improve security of automatic switchover strategies. The engineering applications show that the proposed system is practical. © 2010 State Grid Electric Power Research Institute Press.
Chen C.,Tsinghua University |
Wu W.,Tsinghua University |
Zhang B.,Tsinghua University |
Qin J.,Shenzhen Power Grid |
Guo Z.,Shenzhen Power Grid
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2012
Active distribution system refers to the distribution grid integrated with distributed generations (DGs) and energy storage devices. In order to improve active distribution system reliability evaluation efficiency with good approximation of wind power variation, a model based on Latin hypercube sampling and scenario reduction techniques was proposed and a generalized systematic reliability evaluation method for active distribution system was developed. When a fault occurred in transmission components, part of active distribution system could be isolated from the main grid and operated as a microgrid. In a microgrid, for each wind power scenario, the values of load consumption and power generation were compared and when the power output could not satisfy the load consumption, a load shedding strategy was performed. Then the load shedding probabilities were obtained after all the wind power scenarios were searched. Based on islanding probability, using total probability formula, the reliability indices for load points and system were obtained. The algorithm was applied into a modified IEEE RBTS test system. It is verified that the new method can balance the computation efficiency and accuracy of wind power reliability model. The test results show that wind power integration can effectively improve the reliability level of the corresponding microgrid in the distribution system. © 2012 Chin. Soc. for Elec. Eng.
Li Z.,China Electric Power Research Institute |
Chen W.,State Grid Corporation of China |
Dai M.,China Electric Power Research Institute |
Li Z.,State Grid Corporation of China |
And 2 more authors.
Dianwang Jishu/Power System Technology | Year: 2014
It is attempted for Chinese scholars to apply insulation pole composed of composite material in the erection of 110 kV overhead transmission lines located at the regions with strong lightning activity and/or serious pollution to enhance the phase-to-ground air gap distance and creepage distance effectively. However, with the enhancement of insulation level whether the overhead ground wire should be erected on the composite material pole as well as its grounding downlead should be equipped are key problems that the lightning protection technology has to be faced with. As to the composite material pole for 110 kV transmission lines, the lightning performances of transmission line erected on it without overhead grounding wire and those of 110 kV transmission line erected on the steel tower with the same conductor heights are contrasted and researched, and considering the differences in such factors as lightning attracting ability, lightning impulse dielectric strength and probability of sustained arc between the two kinds of transmission lines it is found that the difference in the lightning attracting ability between the two kinds of transmission lines can be neglected; the lightning impulse dielectric strength of composite material pole without overhead grounding wire is higher than that of steel tower by 3.5 times and the probability of sustained arc of the former is only 53% of the latter, however, the lightning withstand level of the former is only 24.5 kA and the lightning outage rate of the former reaches up to 1.13 times/(100 km·a), and the two indices of composite material pole are obviously worse than those of steel tower. For reasons given above, it is recommended to erect overhead ground wire on composite material poles. Besides, through comparing the estimated results of the differences of lightning performances under various grounding schemes it is found that if the overhead ground line erected on the composite material pole is not grounded via the grounding downlead, the lightning performance of composite material pole is evidently worse than that of steel tower, therefore it is proposed that the overhead ground wire erected on the composite material pole should be grounded one after another. In conclusion, during the design of lightning protection and grounding scheme for 110 kV transmission line erected on composite material poles the overhead ground wire should be erected and the grounding of the overhead ground wire should be grounded via metal downlead one after another. ©, 2014, Power System Technology Press. All right reserved.
Li D.Y.Y.,TU Dortmund |
Rehtanz C.,TU Dortmund |
Xiu R.,Shenzhen Power Grid
2010 9th Conference on Environment and Electrical Engineering, EEEIC 2010 | Year: 2010
In this paper, A non-linear analysis tool based on Hilbert-Huang Transform (HHT) is used to extract timevarying oscillations characteristics from the information provided by Wide Area Measurement System(WAMS). The filtered signal is decomposed into finite numbers Intrinsic Mode Functions (IMFs) by Empirical Mode Decomposition (EMD), and then the instantaneous parameters, including frequency, amplitude and damping ratio of dominant IMF will be obtained by Hilbert Transform (HT) and specific calculating formula. Both the results of simulations and the actual applications in power system show that it is a powerful tool for the oscillation research.
Wang Y.,Xi'an Jiaotong University |
Ji S.,Xi'an Jiaotong University |
Zhang Q.,Xi'an Jiaotong University |
Ren J.,Xi'an Jiaotong University |
And 2 more authors.
IEEE Transactions on Plasma Science | Year: 2014
The detection of gas decomposition products is widely used to diagnose the inner condition of SF6-insulated electrical equipment for its anti-interference ability and high sensitivity. A discharge chamber with Teflon coating inside was designed, with adjustable defect parameters and the volume nearly the same as real ones in gas-insulated switchgear. With the assistance of newly developed dual gas chromatography detection system, this paper investigated the influences of relatively low moisture on the discharge characteristics and gas decomposition under corona and mild spark in SF 6. Considering notable hydrolysis reactions in the main gas volume and on the vessel walls, SO2F2, SO2, and S 2OF10 were selected as typical gas decomposition products. The average discharge capacity and its fluctuation were found to decrease with the increase of moisture content within research scope, which is related to the electronegativity of water molecule. The concentration of typical decomposition products under various moisture conditions was observed in detail. The results show that in mild spark, O atom in S2OF10 mainly originated from oxygen rather than water vapor in SF6. To diagnose internal insulation condition by only monitoring, the magnitude of discharge capacity is proved unreliable. A new parameter, the concentration ratio of SO2/S2OF10, was proposed to group moisture content and discharge types. © 2014 IEEE.
Xiong P.,Zhejiang University |
Sun D.,Zhejiang University |
Deng L.,Shenzhen Power Grid
Dianwang Jishu/Power System Technology | Year: 2016
Aiming at operation of grid-connected voltage-sourced converters (VSC) under universal and dynamically varied harmonic voltage conditions existing in real power grid, this paper proposes an improved sliding-mode-based direct power control (SMC-DPC) strategy under universal harmonic grid voltage. Due to tasks to all harmonics, its implementation has no need of accurate detection of concrete order and phase position of harmonics, thus with certain engineering application potentials. Based on past researches, integral mathematic model of VSC under universal harmonic circumstances is founded, three different control objectives, i.e. sinusoidal current output, active and reactive power fluctuation eliminations, are devised and final improved SMC-DPC strategy under universal harmonic grid voltage is performed. Simulation results reveal that the improved strategy enhances VSC operating performance under universal grid harmonic voltage, contrasting to traditional SMC-DPC. © 2016, Power System Technology Press. All right reserved.
Chen W.,Chongqing University |
Du J.,Chongqing University |
Ling Y.,Shenzhen Power Grid |
Xie B.,Chongqing University |
Long Z.,Chongqing University
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2013
Based on the air-gap discharge model in oil-paper insulation, the experiments on the developing characteristics of partial discharge were performed using constant voltage method in laboratory. In this paper, the variation of discharge energy in discharge development process is studied. At the same time, the discharge repetition ratio n is introduced, and the average discharge energy per second Wasec is proposed as a new feature quantity. The analysis shows that Wasec can be used to describe the development characteristics of partial discharge very well. On the basis of constructing the PRPD spectrum, the line frequency phase(φ)occurred in discharge is introduced, and a three-dimensional statistical spectrum, φ-w-n based on discharge energy is constructed. The partial discharge two-dimensional gray scale images based on discharge energy and phase, w-φ are obtained. As traditional moment parameter has its shortages, the wavelet theory was introduced into the moment characteristic parameter extracting process of partial discharge gray scale images; 62 group sample points for start discharge, developing and breakdown, and the wavelet moment features for different scale parameters and translation parameters were obtained from the gray scale images. According to the wavelet moment features extracted at different discharge times, under the condition of no prior knowledge, the fuzzy C-means clustering method is used to divide the whole air-gap discharge process into four stages, namely, the start discharge and shock developing stage, the weak discharge stage, the outbreak discharge stage and the discharge pre-breakdown stage.
Yu Z.Q.,Yangtze River Scientific Research Institute |
Wang X.,Shenzhen Power Grid
Advanced Materials Research | Year: 2014
The test data of circuit-breaker operating characteristics is important parameter to monitor the circuit- breaker. The unexpected opening of ABB HPL Series circuit-breaker under 30% control voltage in the recent operating characteristics in Shenzhen is analysed in this paper.The root cause of failure is identified. Two solutions are proposed: adjust the gap between coil and armature and replace the trip coil "open", to eliminate such failures, ensure the safe and reliable operation of the circuit breaker. © (2014) Trans Tech Publications, Switzerland.
Lin C.-Z.,Shenzhen Power Grid |
Chen X.-K.,CAS Shenzhen Institutes of Advanced Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012
A frequent problem in support vector regression is to select appropriate features or parameters. We present an efficient feature selection method for regression problem where optimal kernel weights and model parameters are learned alternatively. Our approach generalizes v support vector regression and can be formulized as quadratic constrained quadratic programming which can be efficiently solved by level method. Moreover, we introduce an elastic-net-type constrain on the kernel weights. It finds the best trade-off sparsity and accuracy. Our algorithm keeps the useful information and discards redundant information; meanwhile it has the similar properties of v parameter. The experimental evaluation of the proposed algorithm on synthetic dataset and stock marketing price forecasting task show that our method can select suitable features for building model and attain competitive performance. © 2012 Springer-Verlag.