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Li M.,South China University of Technology | Xia C.,South China University of Technology | Qiu G.,Foshan Electrical Power Bureau
Proceedings of the 5th IEEE International Conference on Electric Utility Deregulation, Restructuring and Power Technologies, DRPT 2015 | Year: 2015

Combined with the project which studies the feasibility of replacing a 500kV substation No. 2 main transformer and based on PSCAD/EMTDC, this paper introduces a special auto-transformer model to study the effects of percentages of three-phase winding short circuit voltage on the transformer differential protection under normal operation and fault conditions after replacing the B-phase transformer for No. 2 main transformer with original A-phase transformer for No. 1 main transformer. It is preliminarily concluded that the replacement has little effect on differential protection and a certain degree of asymmetry of the percentage of three-phase winding short circuit voltage is allowed, which provides new ideas and references for further study on three-phase transformer single-phase replacement. © 2015 IEEE.

Wang Z.,University of Electronic Science and Technology of China | Hu J.,University of Electronic Science and Technology of China | Xiao S.,Foshan Electrical Power Bureau | Li H.,University of Electronic Science and Technology of China
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2012

The impact of uneven terrain on the performance of array pattern is analyzed, and a phase compensation algorithm is proposed through the investigation of the relationship between the phase difference of adjacent elements and the terrain slope. With the proposed algorithm, the scanning errors and distortion of the array pattern caused by the uneven terrain is corrected. Then a synthesis method of over-the-horizon radar (OTHR) receive array in irregular terrain is suggested, the suggested method is based on a special sparse array model, and the phase compensation algorithm with the Chebyshev weighting is used to the array optimization. This synthesis method not only reduces the engineering difficulty but also mitigates the impact of irregular terrain on the array performance and finally meets the requirement of OTHR receive array in side-lobe level and main-lobe width. In addition, compared to the traditional Genetic Algorithm in the array optimization for the proposed array model, the proposed algorithm displays better side-lobe performance and better adaptability to different irregular terrains. At last, the simulation results prove the conclusions above. Copyright ©2012 by Editorial Department of Chinese Journal of Radio Science.

Liu X.,Foshan Electrical Power Bureau | Huang J.,Foshan Electrical Power Bureau | Ruan M.,Foshan Electrical Power Bureau | Zeng Q.,Foshan Electrical Power Bureau
Gaoya Dianqi/High Voltage Apparatus | Year: 2014

A method is proposed to estimate maximum inrush current caused by energizing no-load transformer. Based on the mechanism that energizing no-load transformer causes inrush current, according to the basic parameters of transformer's nameplate and the magnetic flux saturation point to establish nonlinear magnetization curve. The linear features of saturated magnetization curve segment is used to estimate the maximum inrush current. The maximum depth and the duration of voltage sag are calculated. According to the magnetic flux decay time to estimate the duration of voltage sag. The process of closing no-load distribution transformer and power transformer is simulated, and the simulated result is compared to the calculated result. It is shown that the proposed method is validity and accuracy.

Xia C.-J.,South China University of Technology | Dai W.-L.,South China University of Technology | Qiu G.-H.,South China University of Technology | Huang D.-Y.,South China University of Technology | Ou M.-X.,Foshan Electrical Power Bureau
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2011

This paper builds up a typical 110 kV bilateral active line AAR simulation mode based on PSCAD/EMTDC. Simulation results show the main factors affecting reclosing are the initial active and reactive power of the contact line, and in order to meet the setting conditions of same-period reclosing, the initial contact line active power should be in a small range, but this is difficult in normal operation and the reclosing hardly works, which results in frequency collapse or loss of voltage in entire substation and other serious consequences in the small power source side of bilateral active line. Therefore, to enhance the power supply reliability of 110 kV bilateral active lines, we analyze the feasibility of synchronism reclosing from the perspective of impact current. The synchronism reclosing can relax the constraints on the frequency difference, greatly increase the chance of reclosing.

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