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Xuchang, China

Dai Q.,Huazhong University of Science and Technology | Duan S.,Huazhong University of Science and Technology | Cai T.,Huazhong University of Science and Technology | Chen T.,XJ Power Co. | Huang L.,Huazhong University of Science and Technology
Dianli Xitong Zidonghua/Automation of Electric Power Systems

Battery charging and swapping stations (BCSSs) for electric vehicles has become an important infrastructure contributing to the development and spread of electric vehicles in China. The cost-benefit model of BCSS is crucial for its commercialization. In this paper, the battery lease mode is chosen as the operation mode of the BCSS. On the grounds of the chosen mode, the cost-benefit model of the BCSS based on the time-varying economic assessment index including net present value is built that considers the whole capital costs, the maintenance and operation fees, employee wages and service returns from swap and charging. Finally, with a BCSS based on leased mode in China as an example, the whole life cycle cost-benefit model is presented and the key elements affecting the station's revenue arc found through a sensitivity analysis. The sequence of sensitivity elements is as follows: the battery swapping price, lease rental of batteries, electricity price, and so on. The model of BCSS and its sensitivity analysis has provided a basis for cost-benefit assessment and decision marking for commercial operation of BCSS of electric vehicles. © 2014 State Grid Electric Power Research Institute Press. Source

Yang Y.,Northeastern University China | Wei Y.,Northeastern University China | Li Z.,XJ Power Co. | Qin S.,Northeastern University China
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument

Aiming at the features that modern industrial processes always have a large number of process variables and the process data usually contain both Gaussion and non-Gaussion information at the same time, a new system performance monitoring and fault diagnosis method based on mixed subspace is proposed in this paper. First, wavelet denoising, PCA and ICA methods are used to carry out process monitoring. Then, the distance similarity method based on PCA characteristic subspace and the cosine similarity method based on ICA subspace are combined to set up fault diagnosis library, calculate the mixed similarity and determine the diagnosis thresholds of various faults. Finally, the online process measurement data are monitored to judge whether the process is normal. We could judge the source and type of the fault in a short time based on mixed similarity when abnormal condition appears. This method could make full use of Guassion and non-Guassion information in the process data. A simulation case study of Tennessee Eastman (TE) process indicates that the proposed method is feasible and efficient. Compared with the variable contribution plot method, the proposed method can locate the fault more quickly and efficiently. Source

Yu J.-H.,Chongqing University | Zhang J.,Chongqing University | Zhang H.-Q.,Chongqing University | Hao Z.-D.,XJ Power Co.
Gaodianya Jishu/High Voltage Engineering

We put forward an improved method to calculate the ground-level electrical field values on the EHV/UHV AC transmission lines by corona discharge. Space charge, which was generated by corona discharge, was simulated by equivalent charge, and was calculated by a new formula, according to the Shockley-Ramo theorem. The calculation by the proposed method is simple. Then the calculated maximum values of the electric field agree with those available in the literatures. Meanwhile, in the real example, the calculation of ground level field can be used to analyze the electromagnetic environment characteristics of the 750 kV compact AC transmission line. Source

Pan D.,XJ Group Corporation | Xie M.-X.,XJ Power Co. | Wang Z.-L.,Hebi Power Supply Company | Yuan L.,XJ Group Corporation | Mei L.-C.,Hebi Power Supply Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

The ordinary synchronization mode in distributed Ethernet network shows low synchronization accuracy and complex network construction, so this paper introduces IEEE1588 clock synchronization protocol to the Ethernet network in smart substation. Calibration characteristics and clock attribute of the IEEE1588 common clock, boundary clock and transparent clock model are analyzed, and the simulation model of network structure of smart substation is built to conduct model verification and calibration characteristic simulation test. Results show that the IEEE1588 protocol used in Ethernet smart substation improves the precision of clock synchronization, simplifies the network structure of smart substation, and has practical value of popularization and application. Source

Han H.-L.,XJ Power Co. | Tang H.,XJ Power Grid Corporation | Chen C.,XJ Power Grid Corporation
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control

This paper summarizes main protection's action and tripping object after action when bus fault or line fault or transformer fault occurs in 500 kV voltage side or 220 kV voltage side or 35 kV voltage side of 500 kV substation. Aiming at breaker failure, the paper offers the scheme of failure protection as the nearby backup protection. On the basis of the scheme, it brings out the remote back-up relay's action when nearby backup failure occurs and the assorting relationship among protections. It details the way of starting nearby backup and remote backup when breaker failure occurs. Aiming at line-protection's transferred tripping, starting breaker failure of bus protection and transformer's synchronism tripping or delay tripping, the paper comprehensively discusses their principles and practical way. Dead zone protection and charge protection of bus tie breaker are discussed, too. Source

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