Central Southern China Electric Power Design Institute
Central Southern China Electric Power Design Institute
Li G.,Hubei Electric Power Company |
Liu X.,Hubei Electric Power Company |
Sun J.,Central Southern China Electric Power Design Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2017
In view of the still existing extra-high voltage (EHV) and ultra-high voltage (UHV) electromagnetic loop networks, the different forms and structures of development of electromagnetic loop networks are summed up with the cases and examples in a provincial power grid. It is believed that the main risk of electromagnetic loop networks lies in the transfer and control of power flow. The degree of coupling is proposed as an index to measure the intensity and risk of electromagnetic loop networks. In terms of network structure optimization and strengthening, it is considered that the higher voltage power system should be strengthened prior to the strongly coupled weak electromagnetic loop, and the short circuit level control and structure simplifying are more important for the weakly coupled strong electromagnetic loop while multilevel electromagnetic loops should be decoupled as soon as possible. Then the typical split schemes of electromagnetic loop networks are analyzed. Since EHV and UHV electromagnetic loop networks will exist for a long period of time, practical power flow transfer control algorithms for single element trip and cascading trip of electromagnetic loop networks are elaborated. Especially, a kind of unconventional stability control measure of the fast tie-element removal strategy after serious fault is put forward to decouple electromagnetic loops and balance power flow for high-power and strong-coupling electromagnetic loop networks. The stability level and transmission ability of the electromagnetic loops are effectively enhanced. The research results have been applied in actual power grids with good effect. © 2017 Automation of Electric Power Systems Press.
Xu Z.-D.,Nanjing Southeast University |
Tu Q.,Nanjing Southeast University |
Tu Q.,Central Southern China Electric Power Design Institute |
Guo Y.-F.,Nanjing Southeast University
JVC/Journal of Vibration and Control | Year: 2012
The earthquake excitation is a complicated multidimensional motion, which will cause the damage or even collapse of structures. Consequently, some measures to prevent structure failure must be taken under multidimensional excitations, especially for long-span reticulated structures and high-rise buildings. Many earthquake isolation or mitigation devices have been manufactured to reduce the horizontal dynamic responses of structures, but there are few reports concerning the device isolating and mitigating earthquake actions both in horizontal and vertical directions simultaneously. In this paper, a new multidimensional earthquake isolation and mitigation device for long-span reticulated structures is developed and tested under different cases. Effects of excitation frequency and amplitude on vertical properties of this device are studied. Then, the modified equivalent standard solid model is proposed to describe the vertical properties of the device. Experimental and numerical studies show that this device has good capability of energy dissipation in vertical direction. © The Author(s) 2011 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Yang X.-L.,Wuhan University of Science and Technology |
Ding J.-H.,Central Southern China Electric Power Design Institute |
Hou H.,Wuhan University of Technology
Natural Hazards | Year: 2013
Flood risk evaluation and prediction represents an essential analytic step to coherently link flood control and disaster mitigation. The paper established a hybrid evaluation model based on fuzzy analytic hierarchy process (AHP) and triangular fuzzy number. It comprises flood risk evaluation and prediction to obtain risk factors ranking and comprehensive flood risk prediction, and then analyzed flood risk response measures. A case study is proposed entailing a flood risk evaluation and prediction in the Lower Yangtze River region. The evaluation results showed that the proposed evaluation and prediction model was capable of adequately representing the actual setting. In addition, a comparison with the previously described AHP and trapezoidal fuzzy AHP, and experimental results are encouraging, which fully demonstrates the effectiveness and superiority of the proposed model. © 2013 Springer Science+Business Media Dordrecht.
Huang D.,Wuhan University |
Wu G.,Central Southern China Electric Power Design Institute |
Ruan J.,Wuhan University
IEEE Transactions on Plasma Science | Year: 2015
The static and dynamic voltage distribution characteristics and voltage sharing design of a 126-kV modular triple-break vacuum circuit breaker (VCB) was discussed in this paper. The finite-element method and power frequency tests were used to calculate and verify the static voltage distribution ratios and distributed capacitance parameters of multi-break VCBs, respectively. A model combining the post arc current model and equivalent capacitance model was proposed for simulations of dynamic transient recovery voltage (TRV) distribution characteristics of the triple-break VCB. The simulation results indicated that besides the stray capacitances, the TRV sharing design should take the influence of residual charge (RC) into account, and the influence of RC on the TRV distribution is relevant to the differences of RC parameters among the series interrupters. Therefore, the appropriate value of grading capacitors should meet the requirement of the worst case. Based on the investigation of this paper, a 126 kV U-shaped triple-break VCB prototype with 1000 pF grading capacitors has been produced, and the successful large current breaking tests indicate the good breaking capacity and suitable voltage sharing design of the triple-break VCB. © 2015 IEEE.
Zhang G.-R.,Nanjing Hydraulic Research Institute |
Cheng W.,Central Southern China Electric Power Design Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2011
Aimed at regulated scheme of Three Gorges Reservoir and extreme rainfall events, 10 working conditions were set for stability analysis of bazimen landslide of Zigui county. Transit seepage due to associative action of reservoir water lever fluctuations from 175 to 145 and rainfall infiltration was simulated adopted by SEEP/W software. And by using SLOPE/W software, the computed transit pore water pressures were used for limit equilibrium analysis of this landslide, then the landslide stability factors of different work conditions (different rainfall intensity) were decided and the rainfall could be used to predict landslide at last. The stability study showed it would have a great influence on landslide stability when the rainfall is greater than 150 mm/d, and rainfall infiltration had time delay. In the same condition of rainfall, the influence of one day's rainfall intensity on landslide stability had greater than five day's rainfall intensity. During the process of water lever descending from 175 m to 145 m, the landslide would be instability when the critical rainfall was 100 mm/d. That is to say, the landslide failure probability was high during the rapid drawdown. During the process of water lever ascending from 145 m to 175 m and the stable water lever of 175 mm, the landslide would be instability while the critical rainfall was reach to 200 mm/d, that means the landslide failure probability was low under the above two conditions. The results of moisture analysis on landslide showed that it mainly influenced upper soil by rainfall, and lower soil's moisture was controlled by underground water, which indicated rainfall was accessible to cause shallow slope and local slope.
Chen Y.,Hubei Engineering University |
Zhou C.,Hubei Engineering University |
Mao X.,Central Southern China Electric Power Design Institute |
Hu R.,Hubei Engineering University
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2010
To reduce the seepage of the underground opening in Shuibuya hydropower project and improve the seepage stability of the surrounding rocks, a seepage control system including grouting curtain, drainage hole array and drainage tunnels is designed and deployed. The long-term seepage control effects of the surrounding rocks of the underground powerhouse are performed by a stationary seepage analysis method combining the variational inequality formulation of Signorini's type with an adaptive penalty Heaviside function to guarantee the numerical stability and convergence. Meanwhile, the difficulty in finite element mesh generation is reduced and the calculation time and modeling accuracy are balanced with a global model of equivalent modeling and a submodel of accurate modeling for drainage hole array. Intuitive criteria for assessment of the reasonability of the numerical results are established, namely stationary seepage free surface in any homogeneous medium must be continuous, smooth and can not be return-curved, unless it intersects with an interface between two media of distinct permeabilities. By making comparison with the measurements of pore water pressures in the surrounding rocks, the feasibility and effectiveness of the proposed model are demonstrated. The reasonability of the design of the seepage control system and the possibility of its further optimization are illustrated. The research results are helpful for optimization design of the seepage control system in similar projects.
Yuan Z.,Huazhong University of Science and Technology |
Luo C.,Central Southern China Electric Power Design Institute |
Fang C.,Xihua University |
Chen S.,Huazhong University of Science and Technology |
He J.,Huazhong University of Science and Technology
Gaodianya Jishu/High Voltage Engineering | Year: 2013
In order to realize rapid and accurate prediction of zero crossing point of fault current, we designed a control system for fault phase selection. Based on the fault phase selection principle, a digital signal processor (DSP) TMS320F2812 was used as the kernel to complete the design of control system's hardware together with enriching its peripherals. The mutation-amount of phase-current and an improved half-wave Fourier algorithm were adopted to detect the initial time of fault current and reconstruct the waveform, respectively, and a control system software was designed. Moreover, we tested the system through experiments, and the results showed that the control system was accurate and stable: prediction time of zero-crossing point was less than 12 ms, and statistical result of 3σ of prediction errors (σ is standard deviation) was [-0.6, 0.6] ms. The precision meets the demands of controlled interruption of the International Council on Large Electric Systems (CIGRE).
Zhao L.-H.,Central Southern China Electric Power Design Institute |
Gao J.-Q.,Central Southern China Electric Power Design Institute |
Guo X.-G.,Central Southern China Electric Power Design Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2010
The trend of intelligent electric power equipments is discussed from the construction and development angle of China Smart Grid. Compared with the ordinary ones, the intelligent equipments should have these characteristics, such as visualization, informatization, automation and interaction. Based on these characteristics, this paper analyzes the technical requirements and the feasibility of intelligent equipments, and presents the influence on power grid with unifies the whole life cycle theory. Furthermore, the problems caused by intelligent equipments in engineering design process are put forward.
Liu H.,China Earthquake Administration |
Bo J.,China Earthquake Administration |
Bo J.,Institute of Disaster Prevention |
Yang J.,Central Southern China Electric Power Design Institute
Yanshilixue Yu Gongcheng Xuebao/Chinese Journal of Rock Mechanics and Engineering | Year: 2012
The pseudo-static method for the seismic stability evaluation of rock slope is recommended by most codes at home and abroad, but it neglects the effects of dynamic properties of rock mass and most of earthquake ground motion characters. Furthermore, the method of earthquake time-history reasonably considering the effects of main factors is time-consuming and laborious. Nowadays, such simplified methods are lacking in the seismic stability evaluation of rock slope, which can reasonably consider the impacts of dynamic properties of rock mass and the characters of earthquake ground motion. Thus, the relation between the seismic and pseudo-static safety factors is constructed and two simplified methods, which can comprehensively utilize respective advantages of the time-history method and pseudo-static method for determining the seismic safety factor of rock slope, are put forward as follows: (1) The statistical models of seismic safety factor of rock slope and pseudo-static safety factor, peak acceleration are provided for the critical slopes. (2) The rectified coefficients of seismic safety factor of rock slope and pseudo-static safety factor are derived, and corresponding correction schemes are suggested for general slopes. The execution procedures of the simplified methods are illustrated using the method combining finite elements with limit equilibrium method through a typical rock slope. The results prove the feasibility and rationality of the suggested methods. The simplified methods proposed provide the valuable methods and the important reference for rapid evaluation aftershock of critical slopes and seismic stability evaluation of general slopes.
Wen M.,Huazhong University of Science and Technology |
Yang F.,Central Southern China Electric Power Design Institute
Dianwang Jishu/Power System Technology | Year: 2012
To perform electromagnetic transient analysis on a part of a large-scale regional power network by PSCAD/EMTDC, the regional power network has to be divided into two parts, namely the internal network and the external network, and then the equivalent simplification of the external power network is carried out. It is necessary for traditional equivalent methods to establish nodal admittance matrix of the external power network and simplify the network by Gaussian elimination, and it leads to heavy calculation burden. For this reason an equivalent method for regional power network based on short-circuit calculation by Power System Analysis Software Package (PSASP) is proposed, that is, by means of simultaneous short-circuit of all boundary nodes the parameters of injection current sources can be obtained; then by means of short-circuiting boundary nodes one by one, the nodal voltage equations, whose number is the same as the number of boundary nodes, are attained, thus the nodal admittance matrix can be simultaneously solved. Adopting the proposed method, corresponding parameters of boundary nodes can be directly solved and the calculation burden is light. Results of simulation of large-scale regional power network containing UHV transmission line show that the short-circuit current of the original regional power network calculated by PSASP basically conforms to that calculated by equivalent network based on PSCAD/EMTDC, thus the correctness of the proposed method is verified. Finally, the proposed method is compared with traditional static equivalent methods, and the application scope of the proposed method is discussed.