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RISS 인기검색어
- 검색키워드
- 저자 : Terzija, Vladimir (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Numerical algorithm for overhead lines protection and disturbance records analysis
Radojevic, Z.,Terzija, V. THE INSTITUTION OF ENGINEERING AND TECHNOLOGY 2007 IET GENERATION TRANSMISSION AND DISTRIBUTION Vol.1 No.2
<P>A new and very efficient numerical algorithm for overhead lines protection is presented. The algorithm particularly improves up-to-date solutions with regard to fault location, adaptive autoreclosure, detailed disturbance records analysis and fault data management. It is based on the two-terminal line currents and voltages acquisition. For this purpose, the synchronised sampling of all analogue input variables, that is, the application of the global positioning system/phasor measurement units, was assumed. The algorithm presented is derived in the spectral domain and based on the application of the discrete Fourier transform. The prerequisite for the successful adaptive autoreclosure functionality realisation was the suitable modelling of the electrical arc. The electrical arc was considered as a source of higher harmonics. These are included in the complete fault model, which was the starting point for the development of this new algorithm. One of the algorithm's sophisticated features is its ability to determine both the arc and the fault resistance. For the purpose of arc modelling, the results of high current laboratory testing are used. The algorithm is tested through computer-based simulation of a line connected to two active networks. On the basis of the results obtained, it is very realistic that the algorithm presented could be implemented in praxis in modern intelligent electronic devices</P>
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New settings-free fault location algorithm based on synchronised sampling
Preston, G,Radojević,, Z M,Kim, C H,Terzija, V IET 2011 IET generation, transmission & distribution Vol.5 No.3
<P>This study presents a new numerical algorithm for fault location on transmission lines. It does not require line parameters, it is settings-free, which is a radical step forward compared to the existing approaches that require this information. Line parameters are only approximately constant, they differ as the loading and weather conditions vary; this affects the accuracy of the existing fault location algorithms. Thus, an approach that does not require line parameters would be more robust, accurate, flexible and cost-effective than those approaches that do require line parameter information to determine the location of the fault. This is essential for the fast and secure elimination of faults on transmission lines; consequently, the solution leads to a significant improvement in the quality of the energy supply. The new algorithm is based on the emerging synchronised measurement technology, using synchronised data sampling at both line terminals. The study presents the algorithm derivation and the results of thorough testing using the ATP-EMTP simulations.</P>
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Fast, <i>In Situ</i> Demagnetization Method for Protection Current Transformers
Zheng, Taiying,Hu, Ende,Yang, Huan,Zhao, Rongxiang,Kang, Yong Cheol,Wall, Peter,Terzija, Vladimir IEEE 2016 IEEE transactions on magnetics Vol.52 No.7
<P>This paper proposes a fast, in situ demagnetization method for protection current transformers (CTs). Simulations show that the method can automatically demagnetize a CT within 300 ms in situ, i.e., while the CT is deenergized but still connected to the substation. Therefore, unlike existing methods that require the CT to be disconnected from the substation, this new method can be used to demagnetize a CT during a short interruption, e.g., the time it takes an autorecloser to operate, rather than requiring an extended outage of the substation. This will dramatically increase the number of opportunities for the demagnetization of protection CTs, which will alleviate the threat of remanent flux in the CT from causing saturation and compromising the performance of power system protection. Furthermore, by demagnetizing the CT in situ, the method avoids the risk of the improper reconnection of the CT, creating a source of hidden failure. The new method uses the existing dc voltage source in the substation to charge the CT and a parallel-connected inductor. An automatic control scheme is presented that manages the charge/discharge of the inductor, and thereby the demagnetization, by controlling three switches that reconfigure an RLC circuit. The additional hardware required by the method is the three switches, the switch controller, and the RLC circuit. The new method is tested for different hysteresis characteristics, levels of remanent flux, and errors in the assumed element parameters and measured hysteresis characteristics using EMTP-RV simulations. The results indicate that the proposed method can quickly and effectively demagnetize a protection CT in situ.</P>
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