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Application of water loop variable refrigerant flow air-conditioning system in large-scale buildings in northern China
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作者 孙婷婷 倪龙 +1 位作者 姚杨 马最良 《Journal of Southeast University(English Edition)》 EI CAS 2010年第2期197-200,共4页
A water loop variable refrigerant flow(WLVRF)air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a va... A water loop variable refrigerant flow(WLVRF)air-conditioning system is designed to be applied in large-scale buildings in northern China.The system is energy saving and it is an integrated system consisting of a variable refrigerant flow(VRF)air-conditioning unit,a water loop and an air source heat pump.The water loop transports energy among different regions in the buildings instead of refrigerant pipes,decreasing the scale of the VRF air-conditioning unit and improving the performance.Previous models for refrigerants and building loads are cited in this investigation.Mathematical models of major equipment and other elements of the system are established using the lumped parameter method based on the DATAFIT software and the MATLAB software.The performance of the WLVRF system is simulated.The initial investments and the running costs are calculated based on the results of market research.Finally,a contrast is carried out between the WLVRF system and the traditional VRF system.The results show that the WLVRF system has a better working condition and lower running costs than the traditional VRF system. 展开更多
关键词 variable refrigerant flow air-conditioning system water loop large-scale building
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Difference between grid connections of large-scale wind power and conventional synchronous generation 被引量:7
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作者 Jie Li Chao Liu +2 位作者 Pengfei Zhang Yafeng Wang Jun Rong 《Global Energy Interconnection》 2020年第5期486-493,共8页
In China, regions with abundant wind energy resources are generally located at the end of power grids. The power grid architecture in these regions is typically not sufficiently strong, and the energy structure is rel... In China, regions with abundant wind energy resources are generally located at the end of power grids. The power grid architecture in these regions is typically not sufficiently strong, and the energy structure is relatively simple. Thus, connecting large-capacity wind power units complicates the peak load regulation and stable operation of the power grids in these regions. Most wind turbines use power electronic converter technology, which affects the safety and stability of the power grid differently compared with conventional synchronous generators. Furthermore, fluctuations in wind power cause fluctuations in the output of wind farms, making it difficult to create and implement suitable power generation plans for wind farms. The generation technology and grid connection scheme for wind power and conventional thermal power generation differ considerably. Moreover, the active and reactive power control abilities of wind turbines are weaker than those of thermal power units, necessitating additional equipment to control wind turbines. Hence, to address the aforementioned issues with large-scale wind power generation, this study analyzes the differences between the grid connection and collection strategies for wind power bases and thermal power plants. Based on this analysis, the differences in the power control modes of wind power and thermal power are further investigated. Finally, the stability of different control modes is analyzed through simulation. The findings can be beneficial for the planning and development of large-scale wind power generation farms. 展开更多
关键词 large-scale wind power generation Conventional synchronous generators Grid connection scheme power control
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Enhancing Renewable Energy Integration:A Gaussian-Bare-Bones Levy Cheetah Optimization Approach to Optimal Power Flow in Electrical Networks
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作者 Ali S.Alghamdi Mohamed A.Zohdy Saad Aldoihi 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第8期1339-1370,共32页
In the contemporary era,the global expansion of electrical grids is propelled by various renewable energy sources(RESs).Efficient integration of stochastic RESs and optimal power flow(OPF)management are critical for n... In the contemporary era,the global expansion of electrical grids is propelled by various renewable energy sources(RESs).Efficient integration of stochastic RESs and optimal power flow(OPF)management are critical for network optimization.This study introduces an innovative solution,the Gaussian Bare-Bones Levy Cheetah Optimizer(GBBLCO),addressing OPF challenges in power generation systems with stochastic RESs.The primary objective is to minimize the total operating costs of RESs,considering four functions:overall operating costs,voltage deviation management,emissions reduction,voltage stability index(VSI)and power loss mitigation.Additionally,a carbon tax is included in the objective function to reduce carbon emissions.Thorough scrutiny,using modified IEEE 30-bus and IEEE 118-bus systems,validates GBBLCO’s superior performance in achieving optimal solutions.Simulation results demonstrate GBBLCO’s efficacy in six optimization scenarios:total cost with valve point effects,total cost with emission and carbon tax,total cost with prohibited operating zones,active power loss optimization,voltage deviation optimization and enhancing voltage stability index(VSI).GBBLCO outperforms conventional techniques in each scenario,showcasing rapid convergence and superior solution quality.Notably,GBBLCO navigates complexities introduced by valve point effects,adapts to environmental constraints,optimizes costs while considering prohibited operating zones,minimizes active power losses,and optimizes voltage deviation by enhancing the voltage stability index(VSI)effectively.This research significantly contributes to advancing OPF,emphasizing GBBLCO’s improved global search capabilities and ability to address challenges related to local minima.GBBLCO emerges as a versatile and robust optimization tool for diverse challenges in power systems,offering a promising solution for the evolving needs of renewable energy-integrated power grids. 展开更多
关键词 Renewable energy integration optimal power flow stochastic renewable energy sources gaussian-bare-bones levy cheetah optimizer electrical network optimization carbon tax optimization
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Optimizing Power Flow in Northern Cameroon’s Interconnected Grid: Challenges and Solutions
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作者 Jean Ndoumbe Ivan Basile Kabeina +1 位作者 Michael Koumbou Piembe Martin Ndjock 《Journal of Power and Energy Engineering》 2024年第9期63-83,共21页
This paper presents an analysis of the power flow within the Northern Interconnected Grid of Cameroon. The Newton-Raphson method has been performed, known for its accuracy, under MATLAB software, to model and solve co... This paper presents an analysis of the power flow within the Northern Interconnected Grid of Cameroon. The Newton-Raphson method has been performed, known for its accuracy, under MATLAB software, to model and solve complex power flow equations. This study simulates a series of outage scenarios to evaluate the responsiveness of the grid. The results obtained underline the crucial importance of reactive power management and highlight the urgent need to consolidate the grid infrastructure of North Cameroon. To increase grid resilience and stability, the paper recommends the strategic integration of renewables and the development of interconnections with other power grids. These measures are presented as viable solutions to meet current and future energy distribution challenges, ensuring a reliable and sustainable power supply for Cameroon. 展开更多
关键词 power flow Northern Interconnected Grid NEWTON-RAPHSON MATLAB Grid Stability
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Mathematical Modeling and Control Algorithm Development for Bidirectional Power Flow in CCS-CNT System
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作者 Sinqobile Wiseman Nene 《Journal of Power and Energy Engineering》 2024年第9期131-143,共12页
As the demand for more efficient and adaptable power distribution systems intensifies, especially in rural areas, innovative solutions like the Capacitor-Coupled Substation with a Controllable Network Transformer (CCS... As the demand for more efficient and adaptable power distribution systems intensifies, especially in rural areas, innovative solutions like the Capacitor-Coupled Substation with a Controllable Network Transformer (CCS-CNT) are becoming increasingly critical. Traditional power distribution networks, often limited by unidirectional flow capabilities and inflexibility, struggle to meet the complex demands of modern energy systems. The CCS-CNT system offers a transformative approach by enabling bidirectional power flow between high-voltage transmission lines and local distribution networks, a feature that is essential for integrating renewable energy sources and ensuring reliable electrification in underserved regions. This paper presents a detailed mathematical representation of power flow within the CCS-CNT system, emphasizing the control of both active and reactive power through the adjustment of voltage levels and phase angles. A control algorithm is developed to dynamically manage power flow, ensuring optimal performance by minimizing losses and maintaining voltage stability across the network. The proposed CCS-CNT system demonstrates significant potential in enhancing the efficiency and reliability of power distribution, making it particularly suited for rural electrification and other applications where traditional methods fall short. The findings underscore the system's capability to adapt to varying operational conditions, offering a robust solution for modern power distribution challenges. 展开更多
关键词 Capacitor Couple Substation Ferroresonance power flow Control Controllable Network Controller Capacitor-Coupled Substation Incorporating Controllable Network Transformer (CCS-CNT) System System Modeling
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Industrial Arrangement of Large-scale,Non-grid-connected Wind Power Industrial Zones in Coastal Areas of China
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作者 JIN Pingbin FU Zhiwei BAN Maosheng 《Chinese Geographical Science》 SCIE CSCD 2012年第1期109-118,共10页
Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge ... Constructing an industrial system for a large-scale,non-grid-connected wind power industry is a key step towards the diverse utilization of wind power.However,wind power exploitation is not only a technical challenge but an industrial problem as well.The objective of this study is to introduce a concept of large-scale,non-grid-connected wind power(LSNGCWP) industrial zones and establish an evaluation model to assess their industrial arrangement.The data of wind energy,industry,nature resources and socio-economy were collected in this study.Using spatial overlay analysis of geographic information system,this study proposes a spatial arrangement of the LSNGCWP indus-trial zones in the coastal areas of China,which could be summarized as the 'one line and three circles' structure,which will contribute to the optimization of the industrial structure,advance the wind power technology,coordinate the multi-industrial cooperation,and upgrade the industrial transformation of China's coastal areas. 展开更多
关键词 coastal areas in China wind energy resources large-scale non-grid-connected wind power industry industrial arrangement
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A Fluid Experiment of Large-Scale Topography Effect on Baroclinic Wave Flows
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作者 李国庆 Robin Kung Richard L.Pfeffer 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1992年第1期17-28,共12页
The effects of topography on baroclinic wave flows are studied experimentally in a thermally driven rotating annulus of fluid.Fourier analysis and complex principal component (CPC) analysis of the experimental data sh... The effects of topography on baroclinic wave flows are studied experimentally in a thermally driven rotating annulus of fluid.Fourier analysis and complex principal component (CPC) analysis of the experimental data show that, due to topographic forcing, the flow is bimodal rather than a single mode. Under suitable imposed experimental parameters, near thermal Rossby number ROT = 0.1 and Taylor number Ta = 2.2 × 107, the large-scale topography produces low-frequency oscillation in the flow and rather long-lived flow pattern resembling blocking in the atmospheric circulation. The 'blocking' phenomenon is caused by the resonance of travelling waves and the quasi-stationary waves forced by topography.The large-scale topography transforms wavenumber-homogeneous flows into wavenumber-dispersed flows, and the dispersed flows possess lower wavenumbers. 展开更多
关键词 A Fluid Experiment of large-scale Topography Effect on Baroclinic Wave flows
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Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids——An interview with Zhou Xiaoxin, chief scientist of "973 Program"
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作者 Zha Renbo and Zhou Wen Editors of Power and Electrical Engineers ,Zhao Fang 《Electricity》 2008年第4期18-21,共4页
At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a pr... At the end of last year, the editors from Power and Electrical Engineers interviewed Zhou Xiaoxin on "Fundamental Research on Enhancing Operation Reliability for Large-Scale Interconnected Power Grids", a project of "973 Program". Mr. Zhou, the chief engineer of China Electric Power Research Institute(CEPRI) and an academician of Chinese Academy of Sciences, is the chief scientist in charge of this research project. 展开更多
关键词 chief scientist of Fundamental Research on Enhancing Operation Reliability for large-scale Interconnected power Grids An interview with Zhou Xiaoxin Program
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Equivalent Method of Integrated Power Generation System of Wind, Photovoltaic and Energy Storage in Power Flow Calculation and Transient Simulation 被引量:10
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作者 王皓怀 汤涌 +3 位作者 侯俊贤 刘楠 李碧辉 张宏宇 《中国电机工程学报》 EI CSCD 北大核心 2012年第1期I0001-I0026,共26页
针对工程实际开展风光储联合发电系统在潮流计算和机电暂态仿真中的等值方法研究,旨在为大容量风光储联合发电系统的并网仿真分析奠定基础。将潮流计算的等值分为单元机组和集电系统2部分来研究。单元机组等值采用根据不同控制模式选... 针对工程实际开展风光储联合发电系统在潮流计算和机电暂态仿真中的等值方法研究,旨在为大容量风光储联合发电系统的并网仿真分析奠定基础。将潮流计算的等值分为单元机组和集电系统2部分来研究。单元机组等值采用根据不同控制模式选取不同节点类型的方法,针对集电系统等值提出基于损耗不变原则的方法。等值模型和详细模型的算例结果表明,潮流计算等值方法具有较好的精度。在机电暂态仿真动态等值中,基于实际工程计算的最严重工况分析原则,提出运行在满出力点的单机“倍乘”等值模型,为工程计算中的风光储联合发电系统动态等值提供了一种解决方案。 展开更多
关键词 综合发电系统 暂态仿真 光伏发电 潮流计算 等效方法 电力系统 风能 功率
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An Augmented Jacobian Method for Power Flow Analysis of Weakly Looped Distribution Systems with PV Buses
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作者 陈星莺 余昆 单渊达 《Journal of Southeast University(English Edition)》 EI CAS 2002年第3期216-220,共5页
A power flow analysis method for weakly looped distribution systems with PV buses is proposed in this paper. The proposed method is computationally more efficient and more robust compared with the conventional compens... A power flow analysis method for weakly looped distribution systems with PV buses is proposed in this paper. The proposed method is computationally more efficient and more robust compared with the conventional compensation methods. The robustness is achieved by embedding the boundary conditions of loops and PV buses into the Jacobian matrix. The computational efficiency is achieved by the carefully designed factorization of Jacobian matrix. Test results on a 33 bus system are presented. 展开更多
关键词 power flow radial distribution systems weakly loops PV bus
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Design of Large-Scale Prestressing Bucket Foundation for Offshore Wind Turbines 被引量:25
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作者 练继建 丁红岩 +1 位作者 张浦阳 于瑞 《Transactions of Tianjin University》 EI CAS 2012年第2期79-84,共6页
The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads. The finite element model of a large-scale prestressing bucket fou... The key in the force transmission between the tower and the foundation for offshore wind turbines is to transfer the large moment and horizontal loads. The finite element model of a large-scale prestressing bucket founda- tion for offshore wind turbines is set up and the structural characteristics of the arc transition structure of the founda- tion are analyzed for 40-60 channels(20-30 rows) arranged with prestressing steel strand under the same ultimate load and boundary conditions. The mechanical characteristics of the key parts of the foundation structures are illus- trated by the peak of the principal tensile stress, the peak of the principal compressive stress and the distribution areas where the principal tensile stress is larger than 2.00 MPa. It can be concluded that the maximum principal tensile stress of the arc transition decreases with the increasing number of channels, and the amplitude does not change signifi- cantly; the maximum principal compressive stress increases with the increasing number of channels and the amplitude changes significantly; however, for the distribution areas where the principal tensile stress is larger than 2.00 MPa, with different channel numbers, the phenomenon is not obvious. Furthermore, the principal tensile stress at the top of the foundation beams fluctuantly increases with the increasing number of channels and for the top cover of the bucket, the principal tensile stress decreases with the increasing number of channels. 展开更多
关键词 offshore wind power large-scale prestressing bucket foundation arc transition structural design
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Power Flow Response Based Dynamic Topology Optimization of Bi-material Plate Structures 被引量:4
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作者 XUE Xiaoguang LI Guoxi +1 位作者 XIONG Yeping GONG Jingzhong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2013年第3期620-628,共9页
Work on dynamic topology optimization of engineering structures for vibration suppression has mainly addressed the maximization of eigenfrequencies and gaps between consecutive eigenfrequencies of free vibration, mini... Work on dynamic topology optimization of engineering structures for vibration suppression has mainly addressed the maximization of eigenfrequencies and gaps between consecutive eigenfrequencies of free vibration, minimization of the dynamic compliance subject to forced vibration, and minimization of the structural frequency response. A dynamic topology optimization method of bi-material plate structures is presented based on power flow analysis. Topology optimization problems formulated directly with the design objective of minimizing the power flow response are dealt with. In comparison to the displacement or velocity response, the power flow response takes not only the amplitude of force and velocity into account, but also the phase relationship of the two vector quantities. The complex expression of power flow response is derived based on time-harmonic external mechanical loading and Rayleigh damping. The mathematical formulation of topology optimization is established based on power flow response and bi-material solid isotropic material with penalization(SIMP) model. Computational optimization procedure is developed by using adjoint design sensitivity analysis and the method of moving asymptotes(MMA). Several numerical examples are presented for bi-material plate structures with different loading frequencies, which verify the feasibility and effectiveness of this method. Additionally, optimum results between topological design of minimum power flow response and minimum dynamic compliance are compared, showing that the present method has strong adaptability for structural dynamic topology optimization problems. The proposed research provides a more accurate and effective approach for dynamic topology optimization of vibrating structures. 展开更多
关键词 dynamic topology optimization power flow response BI-MATERIAL plate structures
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POWER FLOW ANALYSIS FOR THE FINITE CONTINUOUS ISOLATION SYSTEMS 被引量:3
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作者 Mao Yinghong,Song Kongjie,Sun Yuguo (Institute of Sound and Vibration , Shandong University) 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2001年第3期215-218,共4页
A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with con... A universal expression for the transmitted power to the flexible foundation via the finite continuous isolation system of asymmetry is derived where the concept of effective mobility for the coupled system with continuous contact points is put forward. On the basis of the theoretic calculation and analysis, effects of structure parameters of the system on the power flow transmission as well as on the isolation efficiency are fully investigated. 展开更多
关键词 power flow Finite system of asymmetry CONTINUOUS ISOLATOR
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The power spectrum and correlation of flow noise for an axisymmetric body in water 被引量:3
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作者 黎雪刚 杨坤德 汪勇 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第6期269-276,共8页
Understanding the physical features of the flow noise for an axisymmetric body is important for improving the performance of a sonar mounted on an underwater platform. Analytical calculation and numerical analysis of ... Understanding the physical features of the flow noise for an axisymmetric body is important for improving the performance of a sonar mounted on an underwater platform. Analytical calculation and numerical analysis of the physical features of the flow noise for an axisymmetric body are presented and a simulation scheme for the noise correlation on the hydrophones is given. It is shown that the numerical values of the flow noise coincide well with the analytical values. The main physical features of flow noise are obtained. The flow noises of two different models are compared and a model with a rather optimal fore-body shape is given. The flow noise in horizontal symmetry profile of the axisymmetric body is non-uniform, but it is omni-directional and has little difference in the cross section of the body. The loss of noise diffraction has a great effect on the flow noise from boundary layer transition. Meanwhile, based on the simulation, the noise power level increases with velocity to approximately the fifth power at high frequencies, which is consistent with the experiment data reported in the literature. Furthermore, the flow noise received by the acoustic array has lower correlation at a designed central frequency, which is important for sonar system design. 展开更多
关键词 flow noise correlation analysis power spectrum
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Investigation on Flow Accelerated Corrosion Mitigation for Secondary Circuit Piping of the Third Qinshan Nuclear Power Plant 被引量:3
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作者 ZHAO Liang HU Jianqun +1 位作者 WU Zhigang WANG Kin 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2011年第2期214-219,共6页
Flow accelerated corrosion(FAC) is the main failure cause of the secondary circuit carbon steel piping in nuclear power plants.The piping failures caused by FAC have resulted in numerous unplanned outages and tragic... Flow accelerated corrosion(FAC) is the main failure cause of the secondary circuit carbon steel piping in nuclear power plants.The piping failures caused by FAC have resulted in numerous unplanned outages and tragic fatalities.The existing researches focus on the main factors contributing to FAC,which include metallurgical factors,environmental factors and hydrodynamic factors. Some effective FAC management methods and programs with long term monitoring and inspection data analysis are recommended.But a comprehensive FAC management system should be developed in order to mitigate and manage FAC systematically.In this paper,the FAC influencing factors are analyzed in combination with the operating conditions of the secondary circuit piping in the Third Qinshan Nuclear Power Plant(TQNPP),China(Third Qinshan Nuclear Power Company Limited,China).A comprehensive FAC mitigation and management system is developed for TQNPP secondary circuit piping.The system is composed of five processes,viz.materials substitution,water chemical optimization,long-term monitor strategy for the susceptible piping,integrity evaluation of the local thinning defects,and repair or replacement.With the implementation of the five processes,the material of FAC sensitive pipe fittings are modified from carbon steel to stainless steel,N_2H_4 and NH_3 are finally selected as the water chemical regulator of secondary circuit,the secondary circuit pips are classified according to FAC susceptibility in order to conduct long term monitoring strategy,and an integrity evaluation flow for local thinning caused by FAC in carbon steel piping is developed.If the component with local thinning defects is not fit-for-service,corresponding repair or replacement should be conducted.The comprehensive FAC mitigation and management system with five interrelated processes would be a cost-effective method of increasing personnel safety,plant safety and availability. 展开更多
关键词 flow accelerated corrosion nuclear power plant secondary circuit piping
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PASSIVE-ACTIVE CONTROL OF POWER FLOW IN AN ISOLATION SYSTEM MOUNTED ON FLEXIBLE FOUNDATIONS 被引量:2
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作者 Huo Rui Shi Yin Institute of Naval Ship Equipment Noise & Vibration, Naval University of Engineering Song Kongjie Shandong University of Technology 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2001年第2期111-115,共5页
A general model of flexible isolation systems which involves both the passive and active control factors is established by inserting actuators into an passive isolation system. And the power flow transmission function... A general model of flexible isolation systems which involves both the passive and active control factors is established by inserting actuators into an passive isolation system. And the power flow transmission function in such a system as with multi disturbance, multi mounts, passive isolators and actuators is deduced. By means of the numerical simulation method, the influence of actuators on power flow transmission characteristic is studied. And as a conclusion, the passive active synthetic control strategy of power flow is summarized. 展开更多
关键词 Vibration isolation power flow COUPLING Active control
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POWER FLOW ANALYSIS AND APPLICATION SIMULATION OF ELECTROMAGNETIC CONTINUOUSLY VARIABLE TRANSMISSION 被引量:3
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作者 LUO Yutao TAN Di MENG Fanzhen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2008年第6期48-56,共9页
With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing... With the structure of two air gaps and two rotors, the electromagnetic continuously variable transmission(EMCVT) is a novel power-split continuously variable transmission(CVT). There are two kinds of power flowing through the EMCVT, one is mechanical power and the other is electric power. In the mean time, there are three power ports in the EMCVT, one is the outer rotor named mechanical power port and the other two are the inner rotor and the stator named electric power ports. The mechanical power port is connected to the driving wheels through the final gear and the electric ports are connected to the batteries through the transducers. The two kinds of power are coupled on the outer rotor of the EMCVT. The EMCVT can be equipped on the conventional vehicle being regarded as the CVT and it also can be equipped on the hybrid electric vehicle(HEV) as the multi-energy sources assembly. The power flows of these two kinds of applications are analysed. The back electromotive force(EMF) equations are illatively studied and so the dynamic mathematic model is theorized. In order to certify the feasibility of the above theories, three simulations are carried out in allusion to the above two kinds of mentioned applications of the EMCVT and a five speed automatic transmission(AT) vehicle. The simulation results illustrate that the efficiency of the EMCVT vehicles is higher than that of the AT vehicle owed to the optimized operation area of the engine. Hence the fuel consumption of the EMCVT vehicles is knock-down. 展开更多
关键词 Electromagnetic continuously variable transmission power flow analysis back electromotive force application simulation
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Analysis and management strategies for the low voltage problems of rural power grid based on the distribution network flow calculation method 被引量:2
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作者 陈曦 何俊宏 HE Yu-cheng 《Journal of Chongqing University》 CAS 2015年第4期134-140,共7页
For a long time, because of the lack of investment capital and enough attentions, the overall constructions of rural power grid were far behind than the urban power grid in Chongqing Jiangbei Power Company. The low vo... For a long time, because of the lack of investment capital and enough attentions, the overall constructions of rural power grid were far behind than the urban power grid in Chongqing Jiangbei Power Company. The low voltage problems were highlighted in the rural power grid due to the characteristics of rural power grid. Using the distribution network flow calculation method, we evaluated the low voltage problems of the rural power grid which belongs to Chongqing Jiangbei Power Company. In addition, we collected the data of distribution transformers in electricity consumption peak period. Some practical management strategies were proposed by the analysis and evaluation of potential and appeared low voltage problems. 展开更多
关键词 RURAL power GRID flow CALCULATION method low VOLTAGE PROBLEM management strategy
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Power consumption and flow field characteristics of a coaxial mixer with a double inner impeller 被引量:4
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作者 刘宝庆 张义堃 +2 位作者 陈明强 厉鹏 金志江 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第1期1-6,共6页
A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Ru... A coaxial mixer meeting the actual demand of a system with high and variable viscosity is investigated. It has an outer wall-scraping frame and a double inner impeller consisting of a four-pitched-blade turbine and Rushton turbine. The power consumption and flow field characteristics of the coaxial mixer in laminar and transitional flow are simulated numerically, and then the distribution of velocity field, shear rate and mass flow rate are analyzed. The simulation results indicate that the outer frame has little effect on the power consumption of the double inner impeller whether in laminar or transitional flow, whereas the inner combined impeller has a great effect on the power consumption of the outer frame. Compared with the single rotation mode, the power consumption of the outer frame will decrease in co-rotation mode and increase in counter-rotation mode. The velocity, shear rate and mass flow rate are relatively high near the inner impeller in all operating modes, and only under double-shaft agitation will the mixing performance near the free surface be improved.In addition, these distributions in the co-rotation and counter-rotation modes show little difference, but the co-rotation mode is recommended for the advantage of low power consumption. 展开更多
关键词 Coaxial mixer power consumption flow field characteristics Numerical simulation
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General Model to Predict Power Flow Transmitted into Laminated Beam Bases in Flexible Isolation Systems 被引量:1
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作者 NIU Jtmchuan GE Peiqi +2 位作者 HOU Cuirong LIM C W SONG Kongjie 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2009年第2期227-232,共6页
For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flex... For estimating the vibration transmission accurately and performing vibration control efficiently in isolation systems, a novel general model is presented to predict the power flow transmitted into the complicate flexible bases of laminated beams. In the model, the laminated beam bases are simulated by the first-order shear deformation laminated plate theory, which is relatively simple and economic but accurate in predicting the vibration solutions of flexible isolation systems with laminated beam bases in comparison with classical laminated beam theories and higher order theories. On the basis of the presented model, substructure technique and variational principle are employed to obtain the governing equation of the isolation system and the power flow solution. Then, the vibration characteristics of the flexible isolation systems with laminated bases are investigated. Several numerical examples are given to show the validity and efficiency of the presented model. It is concluded that the presented model is the extension of the classical one and it can obtain more accurate power flow solutions. 展开更多
关键词 power flow vibration isolation plate theory flexible system
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