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Efficient algorithms for real-time monitoring of transmission line parameters and their performance with practical synchrophasors

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IET GENERATION TRANSMISSION & DISTRIBUTION 2017年第5期11卷 1134-1143页

作者： Gurusinghe, Dinesh Rangana Rajapakse, Athula D. Univ Manitoba Dept Elect & Comp Engn Winnipeg MB R3T 5V6 Canada

Accurate transmission line parameters are important for many applications that ensure reliable operation of a power system. The traditional theoretical calculations and offline measurements are widely used approaches obtaining line parameters, but they do not allow tracking of the parameters that change with the environmental factors and load conditions. Synchrophasor-based real-time transmission line parameter monitoring algorithms can track the changing parameters. In this study, two novel line parameter estimation algorithms: a lump parameter model and a distributed parameter model are proposed. The performance of the new algorithms are evaluated under various operating conditions using a real-time digital simulator, and compared with six existing algorithms in terms of both accuracy and computational efficiency. The algorithms were also tested and compared using synchrophasor data obtained from a hardware experimental setup. Furthermore, application of the algorithms to an actual 230kV transmission line is demonstrated. Finally, the sensitivity of the estimated parameters to bias errors in the measurements is analysed.

关键词： power transmission lines phasor measurement parameter estimation environmental factors load conditions synchrophasor-based real-time transmission line parameter monitoring algorithm parameter estimation algorithm distributed parameter model real-time digital simulator voltage 230 kV

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A distributed parameter model and its application in optimizing the plate-fin heat exchanger based on the minimum entropy generation

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2010年第8期49卷 1427-1436页

作者： Zhang, Lina Yang, Chunxin Zhou, Jianhui Beijing Univ Aeronaut & Astronaut Sch Astronaut Sci & Engn Beijing 100191 Peoples R China

A general three-dimensional distributed parameter model (DPM) was developed for designing the plate-fin heat exchanger (PFHE). The proposed model, which allows for the varying local fluid thermophysical properties inside the flow path, can be applied for both dry and wet working conditions by using the uniform enthalpy equations. The grids in the DPM were generated to match closely the flow passage of the heat exchanger. The classical correlations of the heat transfer and the flow friction were adopted to avoid solving the differential equations. Consequently, the computation burden of DPM becomes significantly less than that of the Computational Fluid Dynamics method. The optimal design of a PFHE based on the DPM was performed with the entropy generation minimization taken into consideration. The genetic algorithm was employed to conduct the optimization due to its robustness in dealing with complicated problems. The fin type and fin geometry were selected optimally from a customized fin database. The PFHE included in an environmental control system was designed by using the proposed approach in this study. The cooling performance of the optimal PFHE under both dry and wet conditions was then evaluated. (C) 2010 Elsevier Masson SAS. All rights reserved.

关键词： Plate-fin heat exchanger distributed parameter model Optimization Minimum entropy generation

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Study on the Influence of Structural parameters of Multi-channel Cylinder Dryer on Heat Transfer Performance

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Journal of Energy and Power Engineering 2017年第7期11卷 454-464页

作者： Yan Yan Dong Jixian Shaanxi University of Science & Technology Xi 'an 710021 China

An approach to design multi-channel cylinder dryer was proposed. The heat transfer performance and flow characteristic under various structural parameters were analyzed. First, an experiment was designed and set up to measure the condensing heat transfer coefficient and the pressure drop in order to ,~erify the applicability of the Cavallini＇s correlation. Then, the relationship among the count of channels, aspect ratio, spacing ratio, width, height and hydraulic diameter of a channel was given. Finally, the correlation of condensing heat transfer and the homogeneous model was introduced in order to observe the heat transfer performance and flow characteristic of the multi-channel cylinder dryer affected by different structures. The study reveals that the structural parameters including count of channels, aspect ratio, spacing ratio of a channel dramatically influence the condensation heat transfer coefficient and frictional resistance of the steam. Based on the selected paper machine, it is suggested that the overall performance of the multi-channel cylinder dryer is best if the count of channels is 150-200, the aspect ratio is 1 ： 3 and the spacing ratio is 1 ： 1-1 ： 3.

关键词： Multi-channel cylinder dryer condensation heat transfer distributed parameter model numerical simulation.

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Thermal performance analysis of SuperORV heat transfer tube at supercritical pressure

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JOURNAL OF NATURAL GAS SCIENCE AND ENGINEERING 2016年 29卷 488-496页

作者： Pan, Jie Li, Ran Lv, Tao Wu, Gang Xian Shiyou Univ Coll Petr Engn Xian 710065 Shaanxi Provinc Peoples R China

Super open rack vaporizer (SuperORV) is a new-type of liquefied natural gas (LNG) vaporizer whose lower half of heat transfer tubes has double tube structure. A distributed parameter model based on energy balance is developed in the present paper with the aim to simulate the thermal performance of SuperORV heat transfer tube at supercritical pressure. Corresponding empirical correlations are used to evaluate the convection heat transfer of LNG and seawater, and the heat transfer enhancement effects of inner fin and twisted tape insert are considered in computation. Good agreement between calculated and experimental data implies the calculation model is reliable. On this basis, the temperature and ice thickness profiles along the heat transfer tube are obtained by numerical solution with or without ice layer presence, the thermal performance of heat transfer tube is analyzed, and the effects of operating parameters and heat transfer enhancement techniques on the thermal performance are discussed. The results indicate that both the operating parameters and the heat transfer enhancement techniques have great influence on the thermal performance, including required minimum tube length, ice thickness and length of formed ice layer. The heat transfer enhancement techniques can improve the heat transfer performance markedly, and the required tube length is reduced by 47.7% while both inner fin and twisted tape insert are applied. (C) 2016 Elsevier B.V. All rights reserved.

关键词： LNG SuperORV Heat transfer tube distributed parameter model Thermal performance Supercritical pressure

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Thermal performance calculation and analysis of heat transfer tube in super open rack vaporizer

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APPLIED THERMAL ENGINEERING 2016年 93卷 27-35页

作者： Pan, Jie Li, Ran Lv, Tao Wu, Gang Deng, Zhian Xian Shiyou Univ Coll Petr Engn Xian 710065 Shaanxi Provinc Peoples R China

As one of the most widely-used liquefied natural gas (LNG) vaporizer, super open rack vaporizer (SuperORV) consists of panel-shaped heat transfer tubes with duplex tube configuration. In this paper, an energy balance-based distributed parameter model for predicting the thermal performance of SuperORV heat transfer tube was developed, where introduces numerous empirical correlations. The results from the model exhibit a good agreement with the experimental data, which implies the calculation model is reliable. Based on this, the heat transfer process of SuperORV heat transfer tube was simulated numerically, the bulk fluid and metal temperature profiles along the heat transfer tube was obtained at the condition with ice formation and heat transfer enhancement measures, the thermal performance of SuperORV heat transfer tube was analyzed, and the effects of operating parameters and heat transfer enhancement measures on the thermal performance were discussed. The results show that the operating parameters have important effects on the thermal performance of heat transfer tube, and the heat transfer enhancement measures can improve the heat transfer performance markedly. The required minimum tube length while both inner fin and twisted tape insert were applied is shortened by 60% compared with that without heat transfer enhancement measures. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： LNG SuperORV Heat transfer tube distributed parameter model Thermal performance

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New Approach for Precisely Measuring the Zero-Sequence parameters of Long-Distance Double-Circuit Transmission Lines

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IEEE TRANSACTIONS ON POWER DELIVERY 2016年第4期31卷 1627-1635页

作者： Hu, Zhijian Xiong, Min Li, Chuanqi Tang, Peng Wuhan Univ Sch Elect Engn Wuhan 430072 Hubei Peoples R China State Grid Tianjin Power Maintenance Co Tianjin 300010 Peoples R China State Grid Nanchang Elect Power Supply Co Nanchang 330000 Peoples R China

Based on transmission-line equations and the distributed parameter model, a new approach is proposed to accurately measure the zero-sequence parameters of long-distance double-circuit transmission lines using voltages and currents measured at the ends of lines. The mathematical model of the proposed method is explained in detail, and the differential equations of two coupled lines with different self parameters were solved for the first time with Laplace transform to obtain all of the zero-sequence parameters. And this approach is easy to implement since the measurement process is simple. PSCAD simulation experimental results of double-circuit 500 kV transmission lines with line lengths changing from 200 to 1000 km and a comparison of the measurement results between the proposed method and the traditional method are shown. Simulation experiments validate that whether the two lines are short or long, the new approach has high accuracy even if there is system white noise and interference from other coupled lines.

关键词： distributed parameter model Laplace transform long-distance double-circuit transmission lines parameter measurement transmission-line equations zero-sequence parameters

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Design of microchannel Fischer-Tropsch reactor using cell-coupling method: Effect of flow configurations and distribution

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CHEMICAL ENGINEERING SCIENCE 2016年 143卷 63-75页

作者： Park, Seongho Jung, Ikhwan Lee, Yongkyu Kshetrimayum, Krishnadash S. Na, Jonggeol Park, Seongeon Shin, Seolin Ha, Daegeun Lee, Yeongbeom Chung, Jongtae Lee, Chul-Jin Han, Chonghun Seoul Natl Univ Sch Chem & Biol Engn Gwanak Ro 599 Seoul 151742 South Korea Seoul Natl Univ Engn Dev Res Ctr Gwanak Ro 599 Seoul 151742 South Korea Korea Gas Corp DME GTL Technol Res Ctr Incheonsinhang Daero 960 Inchon 406840 South Korea

The objective of this study is to design a microchannel Fischer-Tropsch reactor with the evaluation of several flow configurations and distribution effect. A cell coupling computation was carried out for the microchannel reactor of five different flow configurations. In the cell coupling method, all the process and cooling channels are decomposed into a number of unit cells, and then coupled to solve the material and energy balances. The realistic flow distribution effect was incorporated into the model by using results obtained from computational fluid dynamics (CFD). The kinetic model was validated with experimental data, and the results of the reactor model was compared with data taken from the literature and the results were found to be in good agreement. Several case studies were conducted to see the effect of flow configurations, flow distribution, and catalyst loading zones. It was observed that the geometry of cross-co-cross current was found to give the best performance among the designs considered. The study also reveals that flow distribution and catalyst loading zone need to be carefully controlled for the safe, robust, and reliable reactor design and operation. (C) 2016 Published by Elsevier Ltd.

关键词： Fischer-Tropsch Microchannel reactor Reactor design distributed parameter model Gas-to-Liquid process

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Study of multi-twisted-tube gas cooler for CO₂ heat pump water heaters

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APPLIED THERMAL ENGINEERING 2016年 102卷 204-212页

作者： Yang Yingying Li Minxia Wang Kaiyang Ma Yitai Tianjin Univ Dept Thermal Engn Minist Educ Key Lab Medium Low Temp Energy Efficient Utilizat Tianjin 300072 Peoples R China

Multi-twisted-tube type heat exchangers applied in a transcritical CO2 heat pump as gas coolers were investigated. The influence of different numbers of inner tubes on the heat transfer and the pressure drop was discussed by means of experiments and theoretical analysis. The performances of two gas coolers with three and four inner tubes were measured and compared. It is found that heat transfer characteristics of the gas cooler with four inner tubes is better than that with three inner tubes. Based on the theoretical analysis, outlet temperature of water increases with increasing the number of inner tubes at the beginning and the increasing tendency becomes gentle when the number of inner tubes is more than four. But the pressure drop of gas cooler rises greatly with the increment of the number of inner tubes. It is implied from the analysis that the coefficient of performance of CO2 heat pump is not optimum when the outlet temperature of water becomes high by increasing mass flow rate of CO2 and decreasing the mass flow rate of water. In order to get both high COP and high outlet temperature of water, the water side heat transfer coefficient of the gas cooler needs improving. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Multi-twisted-tube CO2 distributed parameter model Gas cooler Heat pump

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New scheme of UHVDC transmission line protection based on Chebyshev window filter

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The Journal of Engineering 2017年第13期2017卷 935-939页

作者： Zhenxing Li Hong Tan College of Electrical Engineering and New Energy China Three Gorges University Yichang People's Republic of China

Based on the analysis of the fault current characteristics in ultra-high-voltage DC (UHVDC) transmission lines, a new method to identify the fault by using the polarity of the current mutation is proposed here. Firstly, the protection scheme here is set up as the distributed parameter model to eliminate the influence of distributed capacitance current and data synchronisation on protection. Furthermore, not only the characteristic harmonics of the DC side but also the electromagnetic coupling of the bipolar DC lines and the interference of the high-frequency pulse are considered; the Chebyshev filter is used to select the low-frequency component. Finally, the results of PSCAD/EMTDC simulation show that the proposed scheme not only has the advantages of reliable and low sampling rate, but also has the ability to withstand the transition resistance and the lightning resistance. In a word, the scheme has important reference value for the actual UHVDC projects.

关键词： lightning protection electromagnetic coupling synchronisation fault diagnosis power transmission faults fault currents Chebyshev filters HVDC power transmission power transmission protection power transmission lines transition resistance lightning resistance PSCAD/EMTDC simulation low-frequency component selection high-frequency pulse bipolar DC lines electromagnetic coupling data synchronisation distributed capacitance current influence elimination distributed parameter model current mutation polarity fault identify fault current characteristics Chebyshev window filter UHVDC transmission line protection

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Parametric distributions of a horizontal-tube falling film evaporator for desalination

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DESALINATION AND WATER TREATMENT 2016年第25期57卷 11699-11711页

作者： Gong, Luyuan Shen, Shengqiang Liu, Hua Mu, Xingsen Dalian Univ Technol Key Lab Liaoning Prov Desalinat Dalian 116024 Liaoning Peoples R China

Three independent experiments which correspond to the characteristic study on the performance of the horizontal-tube falling film evaporators were carried out, and each came out with a validated model for its performance prediction. A comprehensive distributed parameter model was developed based on the above three models to simulate a large tube bundle consisting of 160 rows and 80 columns aluminum-brass tubes in a horizontal-tube falling film evaporator. The simulation was conducted with the superficial evaporation temperature on the shell side of 60 degrees C, the superficial overall temperature difference of 3.0 degrees C, the inlet brine salinity of 30g/kg, the inlet brine spray density of 0.06kg/ms, and the maximum steam inlet velocity of 40m/s. The non-uniform distributions of several thermal parameters are presented and discussed.

关键词： Falling film evaporator Horizontal-tube bundle distributed parameter model Distributions of parameters

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