Shanxi Electric Power Research Institute

Taiyuan, China

Shanxi Electric Power Research Institute

Taiyuan, China
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Min J.,Tsinghua University | Wang L.,Shanxi Electric Power Research Institute
Journal of Membrane Science | Year: 2012

Adsorption heat is an important factor affecting the heat transfer characteristics during the heat and mass transfer across a membrane. The mass transfer affects the heat transfer because it affects the adsorption capacity, which influences the adsorption heat. In this research, formula for calculating the adsorption heat was obtained based on the D-A adsorption equation and mathematical model describing the transmembrane heat and mass transfer was established. The effects of various parameters including the adsorption capacity, adsorption characteristic constants, and system temperature on the adsorption heat were first studied and the effects of the mass transfer on the membrane surface temperatures and transmembrane heat fluxes were then investigated. The uniqueness of this research is to take into account the dependence of the adsorption heat on the adsorption capacity when analyzing the effects of the mass transfer on the heat transfer. When the heat of adsorption is treated as constant as in the previous studies, the membrane surface temperatures and the transmembrane convective and adsorptive heat fluxes all vary linearly with the mass flux. When the heat of adsorption is treated as adsorption capacity dependent, more complicated variations are observed for all those temperatures and heat fluxes. Furthermore, the membrane surface temperatures and transmembrane heat fluxes for variable heat of adsorption are close to those for constant heat of adsorption for a small mass flux but they deviate more from those for constant heat of adsorption for larger mass fluxes. © 2012 Elsevier B.V.


Wang X.,Tianjin Electric Power Research Institute | Lin J.,Tongji University | Li S.,Shanxi Electric Power Research Institute | Zheng W.,State Grid Corporation of China
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2013

Islanding operation is a special operation mode in the smart grid. For a power transmission system, if a connected system is split into several stable islanding sub-systems in time in the optimal islanding operation mode in case of extreme emergency, not only will enormous losses due to large area blackout or even system collapse caused by the spread of the local fault be avoided, but the amount of load shedding and generator tripping might be minimized as well. For a distributed system with distributed generator (DG), optimum islanding operation can bring the potential of DG into full play, while improving the reliability of power supply. The influencing factors of the optimal island partitioning in the smart grid are summed up and all the relevant methods and strategies available at home and abroad are thoroughly analyzed and classified. And the advantages and disadvantages along with key issues of each method are also discussed. Finally, the development tendency and the problems demanding prompt solution are treated. © right.


Xue M.,Shanxi Electric Power Research Institute
Applied Mechanics and Materials | Year: 2014

This paper proposes the modle based on Grey system theory to evaluate conditions of transformer. The model of unequal-interval GM (1,1) and GM(1,1) model including buffer operator are established to predict the values of gas dissolved in oil of transformer. According to the results of prediction,state of power transformer will be divided into five categories in order to propose corresponding repair strategy.The method is effective on providing support for transformer condition maintenance.The proposed method has been verified by the experimental data. © (2014) Trans Tech Publications, Switzerland.


He W.F.,Xi'an Jiaotong University | Dai Y.P.,Xi'an Jiaotong University | Wang J.F.,Xi'an Jiaotong University | Li M.Q.,Xi'an Jiaotong University | Ma Q.Z.,Shanxi Electric Power Research Institute
Applied Thermal Engineering | Year: 2013

The performance of air-cooled steam condensers (ACSCs) is always influenced under the unfavorable effect of wind conditions. It is significant to understand the mechanism of such influences so as to improve and optimize the performance of the condensers. In this study, the flow field around a 2 × 600 MW direct air-cooled power plant at different wind speeds and ambient temperatures is numerically simulated, and the relevant influence mechanism is illustrated. User defined function (UDF) based on steam properties, which plays a critical role in the prediction of condenser back pressures, is proposed to simulate the condensation of the turbine exhaust in the exchangers. It is found that wind speed has great influences on the performance of air-cooled steam condensers due to the variation of pressure distribution around the ACSC platform. Heat transfer rate degrades rapidly, while the fan flow rate rises slightly, with the increase of ambient temperature because the heat transfer potential between ambient air and the turbine exhaust is determined by their temperature difference. Finally, the stable back pressures corresponding to each prescribed wind condition are forecasted according to the comparison between the computational heat transfer rate and the ideal heat rejection. © 2012 Elsevier Ltd. All rights reserved.


Jing M.,Shanxi Electric Power Research Institute
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2010

Positive-sequence polarized voltage of distance relay is discussed with voltage phasor diagram method. The phase angle variation of bus voltage and bus positive-sequence voltage before and after the various asymmetrical faults for long-distance and heavy-load lines are analyzed and compared. The bus positive-sequence voltage is adopted as polarized voltage of distance relay, which can effectively reduce and avoid overreach of distance relay when the grounding fault via fault resistance occurs near the setting point of the distance relay. ©2010 State Grid Electric Power Research Institute Press.


Chang X.,Shanxi Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2015

Supercapacitor is a storage technology proposed as means of supplying short-duration transient energy. Inherent long time constant associated with supercapacitor means that this short-term energy transfer is inefficient. The proposed energy storage system combining supercapacitor and electrolytic capacitor is an improvement to supercapacitor based energy storage system with less volume, less cost and higher efficiency. Although the proposed system structure is simple with only two parallel capacitors, its performance relating to several parameters is improved. Based on constant current discharge mathematical model, relationship between the parallel system parameters and its performance are analysedand verified with experiment. It is shown that the parallel system improves energy transfer efficiency by 10% compared to supercapacitor system, and the efficiency can also be improved by adjusting certain parameters of the parallel system. ©, 2015, Power System Technology Press. All right reserved.


Patent
Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

An evaporative condenser radiating module for steam exhaust of a steam turbine comprises tube bundles and steam-water separating chambers. A steam-water separating chamber (4) between a section A and a section B, a section A downflow cooling section tube bundle (3), a section B downflow cooling section tube bundle (5), and a section C counter flow cooling section tube bundle (8) are disposes at the left side of a central steam-water separating chamber (7). An upper sealed space (10) of the steam-water separating chamber (4) between the section A and the section B is in communication with the central steam-water separating chamber (7) through the section C counter flow cooling section tube bundle (8). A lower sealed space of the steam-water separating chamber (4) between the section A and the section B is in communication with the central steam-water separating chamber (7) through the section B downflow cooling section tube bundle (5). A sealed section A steam entering chamber (2) is arranged on the left side of the steam-water separating chamber (4) between the section A and the section B. The section A downflow cooling section tube bundle (3) is arranged between the section A steam entering chamber (2) and the lower sealed space of the steam-water separating chamber (4) between the section A and the section B. The right side of the central steam-water separating chamber (7) is provided with tube bundles and steam-water separating chambers totally structurally identical with those arranged on the left side of the central steam-water separating chamber (7).


Patent
Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

A main stream temperature control system for a large boiler comprises a PID module, A/D converters (M2, M3, M4, and M5), D/A converters (M6 and M7), electrical water spray adjusting valves (AA101 and AA102) and main stream temperature sensors (T1, T2, T3, and T4) for the boiler. The system uses a function module (f (x)), a differential module, a division module, multiplication modules (F1 and F2), addition and subtraction modules (J1, J2, J3, and J4), set value modules (K1-K6), selection modules (N1 and N2), a time pulse module (S1) and small value comparison modules (Z1 and Z2) in a distributed control system, so as to construct a real-time online optimized circuit and form an independent automatic control system for dynamic tracking and stable control, thereby increasing the thermal economic index of the boiler, and achieving the objective of energy saving and emission reduction.


Patent
Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

An automatic monitoring and alarming device based on large strain of a power transmission tower comprises a solar cell (7), a wireless alarm sending device (6), an insulation basement (5) and a truss with great probability of generating large strain on the power transmission tower. One end of two invar alloy fine rods is respectively fixed on the insulation basement (5). The first invar alloy fine rod (1A) is fixedly adhered to the truss with great probability of generating large strain on the power transmission tower, and the arrangement direction of which is the same as the strain generating direction of the truss. The second invar alloy fine rod (1B) is sleeved with an insulation bushing (4) and is suspended on the outside of the truss with great probability of generating large strain. The solar cell (7), the wireless alarm sending device (6), a metal probe (2) and a metal contact (3) together form an alarm circuit. The strain of the service power transmission tower is automatically monitored and alarmed by the automatic monitoring and alarming device, which solves the problem that the large strain of the power transmission tower body can not be detected in time in the prior art.


Patent
Shanxi Electric Power Research Institute and SHANXI Electrical POWER COMPANY | Date: 2011-08-29

Disclosed is a method for determining the spatial location of a conducting wire and an aerial earth wire of a power transmission line, so as to solve the problem that the method in the prior art is not applicable to determining the spatial location of the conducting wire and the aerial earth wire of the conventional power transmission line with respect to lightning shielding failures. In the present invention, according to the physical locations of the conducting wires and aerial earth wires, the power transmission line shielding efficiency is calculated based on that the corresponding lightning shielding failure trip rate is zero when the exposure arc is zero, thus providing designing and operating units with a reliable analytical method for preventing lightning shielding failures, and meanwhile working out the shielding efficiency of the conducting wire of each phase more accurately, so as to analyze the structural relations between the aerial earth wires and conducting wires to determine the lightning protection effect of the whole power transmission line. The present invention provides a supplementary analytical method of the shielding efficiency of the existing power transmission lines.

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