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Chen M.-Y.,Chongqing University | Zhang P.,Chongqing University | Peng H.,Chongqing Electric Power Company
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering

This paper presents a novel numerical calculation approach for temperature field and ampacity of power cables, which involves localized high gradients and material discontinuity problems consisting of cable and soil, using element free Galerkin method (EFG). The heat transfer analysis of underground cables containing material discontinuities was conducted by applying EFG modeling. Lagrange multipliers method was used to solve material discontinuity. By using the Linked-Cell-List algorithm and non-uniform nodal points, the calculation efficiency of dynamic support domain was improved to mitigate the problem of localized high gradient. Calculation results showed that the EFG method has the advantage of higher accuracy and smaller error in comparison with finite element method. © 2010 Chin. Soc. for Elec. Eng. Source

Wang Y.,Chongqing University | Wan L.,Chongqing Electric Power Research Institute | Hu B.,Chongqing University | Xie K.,Chongqing University | Xiang B.,Chongqing Electric Power Company
Dianwang Jishu/Power System Technology

The stochastic output characteristic of wind power generating units in wind farm is analyzed. Taking the operation strategy, working condition and charging/discharging constraints of energy storage system into account and through all sequential simulation, the operating characteristics and reliability of microgrid operated in isolated island mode are emphatically analyzed. Based on the idea of load partitioning and synthetically considering the two factors of the importance and the position of load, the load shedding strategy under isolated island mode of microgrid is researched. Finally, based on the features of island operation mode two novel reliability indices, namely the first average continuous working period of microgrid operated in isolated island mode and the rate of operational stability, are proposed, and using the two novel reliability indices the reliability evaluation of modified RBTS Bus6 is performed, and simulation results show that the proposed model and reliability evaluation algorithm are effective. Source

Wen X.,Chongqing Electric Power Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

Since power system energy-saving and emission-reducing plays a significant and practical role in sustainable development for human society, the research overview of power system power-purchasing plan is presented from the perspective of energy-saving and emission-reducing. First of all, this paper indicates the research background and significance of power system energy-saving and emission-reducing; then, the processing manners are summarized for energy-saving and emission-reducing according to power dispatch plan and electricity market respectively. The overview of optimization methods for solving power dispatch plan and power-purchasing plan in electricity market are stated and analyzed, and these key problems are pointed out as well. Finally, those important research directions that need to break through are concluded and refined, while providing the reference for this area of research in depth. ©, 2015, Power System Protection and Control Press. All right reserved. Source

Jiang X.-L.,Chongqing University | Du Z.,Chongqing University | Wang H.-Y.,Chongqing Electric Power Company | Zhang Z.-J.,Chongqing University
Gaodianya Jishu/High Voltage Engineering

There are many mountains in Chongqing and the temperature is low in winter. The rivers and the water vapor in air are abundant on the territory of Chongqing. The snow disaster in 2008 seriously affected the security and stability of the grid. Therefore, to study the ice characteristics of wire in Chongqing city, effective measures were taken to prevent ice according to the characteristics. The historical meteorological data from weather stations and field survey data show that the ice is affected by climate, topography, altitude and many other factors, the icing phenomenon is mainly in mountains of Northeast and Southeast of Chongqing regions. The main type of ice is glaze and hard rime. Topography conditions and altitude have more serious impact on the ice, and the shape of ice is crescent. Source

Long H.,Xian Jiaotong University | Long H.,Chongqing Electric Power Company | Xu R.,Chongqing Electric Power Research Institute | He J.,Chongqing Electric Power Research Institute

With the mass introduction of wind power in Northern China, wind power variability has appeared. In this article, both existing electric heat pumps (EHPs) and coal-fired combined heat and power (CHP) facilities, which are generally equipped with extraction-condensing steam turbines coupled with district heating for space heating purposes, are proposed to incorporate the variability of wind power equivalently. The authors' proposal arises from the facts that: (1) EHPs can provide space heating in the domestic sector with little thermal comfort change (e.g., energy carriers for space heating purposes can be switched from heating water to electricity); (2) coal-fired CHP units in Northern China can usually generate more electrical power corresponding to a shaved thermal power production. Thus, it is suggested that heating water from CHP units be shaved when the wind generation is low due to the variability of wind power, so as to enable more electrical power production and compensate for the corresponding insufficient wind generation. Following this, in the future and for some space heating loads at appropriate distances, electricity used as energy carrier should be converted by electric heat pumps for space heating. Thus, more electricity consumption will be achieved so as to avoid wasting wind power when the wind generation it is high. A numerical simulation is performed in order to illustrate the authors' proposal. It is shown that the impact of variability of wind generation can be equivalently reduced to a great extent, which enable more wind power integration instead of curtailment and potential energy conservation. Moreover, in contrast to before, both the thermal and electrical power of coal-fired CHP units are no longer constants. In addition, the ratio of electrical to thermal power of CHP units is no longer constant either, and results in less energy consumption compared with fixed ratio. Finally, electricity consumed by end users' EHPs, which are devoted to space heating for various spatial distances and time points, is figured out. Source

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