The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location an...
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The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location and diagnosis. Current filament, perfect conductive cylinder and perfect conductive spiral coil models are used to simulate the radiation and the influences of iron-core and transformer coil to the propagation of EM waves. The results demonstrate dynamic propagation process of EM waves in time order, and prove the correctness of the shortest optical path principle. But the attenuation and distortion of EM waves-especially the first peak amplitude-caused by the obstruction of large solid conductive obstacle like iron-core are quite intensive that it may cause great difficulties to identify exact arriving time position of incident waves coming along the shortest optical path. While the influences of the coil to the propagation of EM waves are so little that HF EM waves can penetrate it in almost linear path.
The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The available capacities of possible congested transmission lines are consider...
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The paper proposed a novel decentralized approach for congestion management via Optimal Resource Allocation (ORA) for the forward markets. The available capacities of possible congested transmission lines are considered as commonly shared resources for bilateral and multilateral transactions in the market. Each transaction maximizes its profit using limited capacity of transmission line allocated by the ISO. Through the proposed decentralized optimization algorithms, the ISO searches the optimal allocation of the capacities of congested transmission lines to the individual transactions and finally the same market efficiency (social welfare) as centralized optimization is achieved. This decentralized approach is more suitable for power market environment since it does not require private and sensitive information submission from individual transactions to the ISO and the resource allocation decision is always feasible during iterations. The mathematical model, calculation procedure and relevant proof are presented. The computer test results from the IEEE 30 bus system show clearly the effectiveness of the approach and its consistency with the centralized optimization.
In this paper, four 110kV prefabricated cable joints models containing four kinds of known representative insulation defects were designed. The models can simulate some typical PD phenomena, such as sliding discharge,...
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ISBN:
(纸本)9781424416219
In this paper, four 110kV prefabricated cable joints models containing four kinds of known representative insulation defects were designed. The models can simulate some typical PD phenomena, such as sliding discharge, floating discharge, cavity discharge and protrusion discharge. Based on them, type frequency spectrums of AE PD signals in XLPE cable joints were studied. The investigation indicated that the main frequency component of AE PD signals for XLPE cable is less than 400kHz;the attenuation of higher frequency component is very fast;the energy is relatively centralized in 50～250kHz;the sensitivity in this band is very high;the characteristics of different PD models are apparently dissimilar from each other. The obtained results provided basis for future investigation on PD pattern identification.
The distribution network structure planning can enhance the reliability and the efficiency of the grid. An adaptive ant colony algorithm based on cloud model was proposed and applied in distribution network structure ...
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The distribution network structure planning can enhance the reliability and the efficiency of the grid. An adaptive ant colony algorithm based on cloud model was proposed and applied in distribution network structure planning in this paper. In view of the main disadvantage of being inclined to local convergence and slow convergence speed of traditional ant colony algorithm, the parameter ρ and Q were qualitatively controlled and dynamically selected in this paper by employing the uncertain qualitative association rule inference based on cloud model, which is one indefinite model for transformation between qualitative and quantitative knowledge. The algorithm overcomes the shortcoming of traditional ant colony algorithm, and the simulation results of power distribution network planning demonstrated the efficiency of the algorithm.
Unbalanced element brings a big problem to fault analysis of symmetrical components method. According with fault analysis of phase components, a residual voltage transformation method for short-circuit current calcula...
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Unbalanced element brings a big problem to fault analysis of symmetrical components method. According with fault analysis of phase components, a residual voltage transformation method for short-circuit current calculation is presented with matrix translation in the place of classical sequence networks connection, which is suitable for both phase coordinates and symmetrical components coordinates. Calculation formulas are proposed with matrices calculation to deal with unsymmetrical faults and parameter matrices for various faults are listed. Analysis of simultaneous faults with unbalanced parameter element is done without calculation qualities increased. Simple examples have shown that the method is practical and suitable for programming.
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