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Duan Y.,Nanjing Southeast University | Duan L.,Nanjing Southeast University | Hu H.,Nanjing Southeast University | Hu H.,Jiangxi Electrical Power Design Institute | Zhao C.,Nanjing Southeast University
Journal of Southeast University (English Edition) | Year: 2015

The pressurized combustion experiments of bituminous coal and lignite under air and O2/CO2 atmospheres were conducted to study the influences of pressure and atmosphere on combustion and the CO, NO, SO2 release process. Two indices, the maximum concentration and the total emission, were applied to quantitatively evaluate the influence of several different operating parameters such as pressure, atmosphere and temperature on the formation of NO and SO2 during coal combustion in the fluidized bed. The experimental results show that the releasing profiles of CO, NO and SO2 during coal combustion under a pressurized oxy-fuel atmosphere are similar to those under a pressurized air atmosphere, and the curves of measured gas components are all unimodal. Under the oxy-fuel condition, pressure increasing from 0.1 to 0.7 MPa can cause the inhibition of NO and SO2 emission. The elevation of temperature can lead to an increase in the maximum concentration and the total production of NO and SO2, and the increase under atmospheric pressure is higher than that under high pressure. ©, 2015, Southeast University. All right reserved. Source

Chen J.-Y.,Shanghai JiaoTong University | Fan C.-J.,Shanghai JiaoTong University | Liu L.,Jiangxi Electrical Power Design Institute
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

To solve the problem that the traditional longitudinal differential protection used in four-circuit transmission line on the same pole with different levels will be seriously affected by coupling inductance, a new longitudinal differential protection scheme based on inverse-sequence negative sequence difference current is proposed. Four-circuit transmission lines with different voltage grades generally consist of two double circuit transmission lines at the same tower. However, when line parameters are symmetry, the inverted sequence current is zero when the system operates normally or external faults occur. Once internal faults occur, there is inverted current in the transmission line, and the sum of inverted current at both sides is large, so the differential protection based on inverted current can operate correctly. For this method, the reliability and sensitivity under big fault resistance can be kept. And it will not be affected by capacitive current when it is applied to the main protection of four-circuit transmission line with different voltage grades. The theoretical analysis and EMTP simulation results show that the proposed principle is correct and reliable. Source

Zhao L.,NARI Group | Wang M.,Jiangxi Electrical Power Design Institute | Ni M.,NARI Group | Li X.,NARI Group
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2016

The reliability of security and stability control device is important to the operation of electric power grid. Taking SCS-500E which is one kind of security and stability control device for example, the components and their logical relationship in the hardware system of the device are analyzed. Based on the analysis, the fault tree model and the Markov state space model are built by fault tree method and Markov state space methodology. The paper believes that the device has 4 operation states which are normal operation, hidden mal-operation, hidden anti-operation, and outage. The probabilities of the 4 operation states are got by fault tree model and the Markov state space model. Other reliability indexes of the hardware system of the device which are availability, hidden failure probability, and probability of outage caused by hidden failure are also delimited. It is proved that the results worked by the method proposed in the paper are matched with the actual facts and the method is correct. © 2016, Power System Protection and Control Press. All right reserved. Source

Li L.,Hebei University of Technology | Li L.,National Chin - Yi University of Technology | Han Y.,Hebei University of Technology | Chen W.,National Chin - Yi University of Technology | And 3 more authors.
PLoS ONE | Year: 2016

In this paper, an improved algorithm of wavelet packet-chaos model for life prediction of space relays based on volterra series is proposed. In the proposed method, the high and low frequency time sequence components of performance parameters are obtained by employing the improved wavelet packet transform to decompose the performance parameters of the relay into multiple scales. Then the optimization algorithm of parameters in volterra series is improved, and is used to construct a chaotic forecasting model for the high and low frequency time sequence components gained by the wavelet packet transform. At last, the chaotic forecasting results of the high and low frequency components are combined by taking the wavelet packet reconstruction approach, so as to predict the lifetime of the studied space relay. The algorithm can predict the life curve of the relay accurately and reflect the characteristics of the relay performance with sufficient accuracy. The proposed method is validated via a case study of a space relay. © 2016 Li et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Zuo L.-X.,East China Jiaotong University | Ding Q.-F.,East China Jiaotong University | Wu P.,Jiangxi Electrical Power Design Institute
WIT Transactions on Information and Communication Technologies | Year: 2014

The on-line insulation monitoring device of high voltage electrical equipment has played an important role in the intelligent substation; the performance of a signal acquisition system directly affects the accuracy and reliability of the whole device. In this paper, a data acquisition system based on DSP and AD7656 is designed. The design of hardware interface circuits and implementation of software is described. It is a comparatively new data acquisition system, which has high acquisition accuracy and flexible configuration. © 2013 WIT Press. Source

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