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Lin J.-K.,Tianjin University | Wang C.,Tianjin University | Lu X.-Y.,Liaoning Electrical Power Survey and Design Institute | Wu N.-H.,Shandong Electric Power Research Institute
Gaodianya Jishu/High Voltage Engineering | Year: 2011

To accurately simulate transformer saturation and to establish a transformer saturation model, based on UMEC(Unified Magnetic Equivalent Circuit) model and the no-load experiment, a new model considering the magnetic circuit saturation characters of the transformer is proposed. The model uses the UMEC model to describe the relationship of each permeance of magnetic circuit, and the curve of voltage/current and the curve of power loss gained by the no-load experiment are piecewise lined to approximately achieve the relationship of the transformer excitation permeance and excitation current. The advantages of the UMEC model such as needing no winding turns, core cross-sectional area and the length and so on, as well as the relationship between core permeance and yoke permeance, are fully utilized by the model, so that the nonlinearization of the yoke can also be indirectly considered through the nonlinearization of excitation branch; meanwhile, the nonlinearization of excitation branch can be easily obtained by the simple no-load experiment. The simulation results demonstrate that the model possesses high precision, and is conveniently applied for the practical engineering due to the needed parameters being easily obtained. Source

Li G.,LIAONING Technical University | Wang Y.,Liaoning Electrical Power Survey and Design Institute | Lu X.,LIAONING Technical University | Li W.,LIAONING Technical University
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2011

Improving hydraulic properties to elevate the efficiency is an important research content in optimization design of centrifugal pumps. Based on the Reynolds time averaged N-S equations (RANS) and RNG κ-ε turbulence models, the three-dimensional flow field of the IS65-40-250 centrifugal pump with deviated short splitter vanes was simulated in Fluent software. The velocity and pressure of the flow in the centrifugal pump were analyzed and the internal flow rule was revealed. The result showed that by design of short splitter vane, the velocity and uniformity of pressure distribution in the centrifugal pump were improved, and the pressure pulse of impeller exit decreased, and the loss of impact was reduced. According to calculation of head and waterpower efficiency of the improved pump, the head and waterpower efficiency increased by 3.46% and 1.7% respectively, and the purpose of energy saving was achieved. Source

Cao Y.-L.,Shenyang University | Zheng W.,Shenyang University | Zhou Y.-C.,Shenyang University | Cao Y.,Liaoning Electrical Power Survey and Design Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

A practical plan for power flow calculation based on distribution GIS platform is researched. Topology model of distribution network is described by GUID (Globally Unique Identifier) used in distribution power GIS platform. The Node-Switch coding style used in traditional forward and backward substitution method is replaced by GUID, so the more integral, precise and timely updated parameters can be applied to power flow calculation. The calculation module is designed under Matlab environment, and is integrated in GIS platform to realize visual calculation which can visually display the results on distribution power network's map. The plan are used in some rural power enterprise, and the calculation results show that it is practical. Source

Tian L.,Shandong University | Tian L.,Dalian University of Technology | Li H.-N.,Dalian University of Technology | Huang L.-Z.,Liaoning Electrical Power Survey and Design Institute
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2012

Because of large span of model and limitation of laboratory size, it is difficult to keep tower and line with same scaling factor when shaking table testing of a power transmission tower-line system is conducted, and it is needed to modify scaling factor of line. With numerical analysis and based on a 500 kV transmission system of Gaizhou city in Liaoning province, the modified scaling factor of its line was taken as 1.0, 0.5 and 0.4, the scaling of its tower was unchanged, and the longitudinal and transverse seismic responses of the model were obtained under uniform and multiple excitations, respectively. The results showed that the seismic responses of the modified model of the transmission tower-line system keep the same as those of the original model, and the precision of the shaking table testing of the modified model meets the engineering requirements. Source

Yu H.,Liaoning Electrical Power Survey and Design Institute | Cui D.-X.,China Electric Power Research Institute | Qu X.-D.,China Electric Power Research Institute
Dianwang Jishu/Power System Technology | Year: 2010

In previous calculation of step voltage the ground potential raise near the rail due to rail stray current is not taken into account, so the calculation result of step voltage exceeds its true value by 20%. After theoretical derivation, an approximate computation model for ground potential raise near the rail is given, thus the potential difference between the rail and any point close to it can be obtained, besides, a simplified method to calculate the step voltage between the rail top and the point, which is apart from the rail top by 0.8m, is given. Source

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