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Wang Q.,Hohai University | Ma H.,Research Center for Renewable Energy Generation Engineering | Cao S.,Nantong University | Chen B.,Jiangsu Province Key Laboratory of Environmental Engineering
Mathematical Problems in Engineering | Year: 2015

Thrust bearing is one part with the highest failure rate in hydroturbine generator set, which is primarily due to heavy axial load. Such heavy load often makes oil film destruction, bearing friction, and even burning. It is necessary to study the load and the reduction method. The dynamic thrust is an important factor to influence the axial load and reduction design of electromagnetic device. Therefore, in the paper, combined with the structure features of vertical turbine, the hydraulic thrust is analyzed accurately. Then, take the turbine model HL-220-LT-550, for instance; the electromagnetic levitation load reduction device is designed, and its mathematical model is built, whose purpose is to minimize excitation loss and total quality under the constraints of installation space, connection layout, and heat dissipation. Particle swarm optimization (PSO) is employed to search for the optimum solution; finally, the result is verified by finite element method (FEM), which demonstrates that the optimized structure is more effective. © 2015 Qingyan Wang et al. Source


Lin-Jun S.,Research Center for Renewable Energy Generation Engineering | Lin-Jun S.,Hohai University | Lei Z.,Jiangsu Electric Power Company | Min-Hui Z.,Jiangsu DanYang Power Supply Company | Guo-Qing T.,Nanjing Southeast University
DRPT 2011 - 2011 4th International Conference on Electric Utility Deregulation and Restructuring and Power Technologies | Year: 2011

Applications of single Flywheel Energy Storage System (FESS) to suppress power system multi-mode oscillations is presented in the paper. Based on independent active power and reactive power control loops and damping torque analysis, the feasibility of damping power system multi-mode oscillations using single FESS is studied. Based on modal analysis, the effective control loops are determined to install auxiliary damping controllers in FESS and the effective feedback signals to select to suppress each oscillation mode. And the eigenvalue analysis and non-linear simulation results show that single FESS has ability of damping power system multi-mode oscillations by an example of four-machine power system with FESS-based stabilizers. © 2011 IEEE. Source


Yang G.,Hohai University | Yang G.,Research Center for Renewable Energy Generation Engineering | Yang K.,Hohai University | Huang Y.,Hohai University | Jing P.,Hohai University
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2014

Hydraulic metal structural health diagnosing system is a multi-level, multi-standard and multi-factor comprehensive system. Diagnosis indexes are the basis and key elements to development of such system and determination of their weight coefficients has a direct effect on diagnosis results. The importance degree of each index is calculated and analyzed using the fundamental principle of information gain and the information carried by each index for determination of a health grade in the health diagnosis process. This method can eliminate the subjectivity in specifying the weights of the indexes and hence improves the weighting process and diagnosing results. Its calculations of the importance degrees of weight coefficients are close to those by FAHP method. It can be used for guiding data collection and analysis and also for simplification of index system for concise and effective diagnosis analysis. © Copyright. Source


Qian Y.,Hohai University | Qian Y.,Research Center for Renewable Energy Generation Engineering | Hu W.,Hohai University | Lin X.,Nanjing Agricultural University | Wang B.,Hohai University
Proceedings of the 30th Chinese Control Conference, CCC 2011 | Year: 2011

A new active queue management (AQM) algorithm named fractional order proportional integral (FOPI) controller was proposed, which was used for congestion control of networks with traditional wired backbone and wireless terminal user supporting Internet TCP flows. First, the small signal theory was introduced to linearize the dynamic model for the congestion control of wireless networks in the steady state. Second, for meeting the system stability and robustness requirements, the parameters of FOPI were presented based on the frequency specifications concerned with the phase and the gain of the system open-loop transfer function. Simulation results show the excellent robustness performance of FOPI with system parameter variation and external disturbance experiments respectively. © 2011 Chinese Assoc of Automati. Source


Zuo L.,Hohai University | Zuo L.,Research Center for Renewable Energy Generation Engineering | Zheng Y.,Hohai University | Sha Y.,Tsinghua University | Li Z.,Hohai University
Taiyangneng Xuebao/Acta Energiae Solaris Sinica | Year: 2011

An unsteady-state heat transfer model of solar chimney power generation system with the heat storage layer was developed. The characteristic of heat collector and the temperature-improving effect of heat storage layer were studied. The results show that the effects of the surface temperature of heat storage layer, temperature of air flow and temperature of heat collector are interrelated and they have a larger fluctuations with time; The increase of the temperature of air flow occurs mainly at one-third of distance from the air flow entrance to the heat collector radius; The surface temperature of heat storage layer gradually increases along the radial direction, and decreases distinctly at outlet of the heat collector; The heat collector, the bottom of heat storage layer and its surrounding are the major places where heat loses. When the system is unstable, the underlying heat storage layer does not participate in the process of heat transfer to the air in the absence of solar irradiance, but continues to absorb the heat from the shallow heat storage layer, whose heat storage does not entirely pass to the air flow; When the system is stable, the temperature of the bottom of heat storage layer tends to the fixed value; The changing trend of theoretical power generation is in accordance with that of temperature of air flow with time. Source

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