Advanced Materials Research Vols. 1008-1009

Abstract: The model of transformer as a noise source is very critical for substation noise prediction. The transformer is equivalent to several point sources on the basis of regarding the transformer as a combination of several planar sources. This equivalent model is based on equivalent source method and it is convenient and easy. The model of 9 equivalent point sources is simulated to verify that the rebuilt sound field is roughly the same as the actual sound field generated by the plane source. Moreover, the accuracy of the model with different settings was discussed. The acoustic model is accurate and feasible to calculate the noise level radiated by transformer and it is meaningful for substation noise control.

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This paper is related to the vibration analysis of transmission line fitting vibration damper (TLFVD) using commercial ANSYS program. According to the basic structure of the TLFVD, the three dimensional model with different parameters including diameter and length of strand is established. Through the modal analysis of the TLFVD using ANSYS WORKBENCH, the first four-order natural frequencies and mode shapes is obtained. Comparing the simulation data of vibration characteristics, the effects of model parameters on the natural frequency are summarized. Finally, the optimized model has been selected from various models established, and the resonant frequency of the TLFVD was verified by the harmonic response analysis. As a result, the optimized model structure of the TLFVD is presented.

Abstract: This paper first describes a variety of heat transfer which exists in cable’s discharge pipe laying process, and analyzes the entire heat transfer process of 10kV three core cable in a two-dimensional interface qualitatively according to the heat transfer ways. Meanwhile, a finite element model of 10kV three-core cable’s discharged pipe-laying is established, and its temperature field equations and boundary condition equations has been discussed. Finally, we get the heat transfer process of the three core cable’s pipe-laying discharged and a finite element model which can be applied to simulated calculation.

Abstract: The paper focus on the influence of the deviation of material thermal resistance coefficient on the conductor temperature calculations, based on the three-core cable thermal circuit model. Meanwhile we also design a temperature rise test of the 10kv three-core cable in step current, measuring the temperature of the cable structure in different steady state. Then we calculate the thermal resistance of the cable body and the thermal resistance of the layer material , find the change law of the thermal resistance with the temperature and analyses the effect of the dynamic characteristic of the material thermal resistance on the conductor temperature calculations in the three-core cable thermal circuit model.

Abstract: The core of the 10kV three-core cable is in the shape of a trefoil. Not all the radial direction of the actual heat transfer characteristics are the same. The finite element method serve as the three core cable temperature field research method in this text, in order to analyze the internal temperature distribution of three core cable, establish a steady state thermal circuit model in accordance with the characteristics of heat transfer from the cable conductor to the surface in the three-core cable , give the calculation of conductor temperature algorithm, and calculate the various parameters in the model.

Abstract: ±1000kV DC wall bushing is a complex insulation system working in different conditions, such as DC, AC and polarity reversal. No matter what kind of conditions, the space charge effects on the electric field distribution of the bushing are remarkable. A finite element model for ±1000kV DC wall bushing is established based on space charge theory, to analyze the electric field distribution in different conditions, especially when polarity reversal occurs. The research results provide useful references for the electric field analysis and insulation optimization of UHV (ultra high voltage) DC wall bushings.

Abstract: Research and identify overhead transmission lines’ transient characteristic which was caused by lightning stroke is significant to develop the protection and improving its reliability based on transient state. A complex signal can be resolved into several parts which have respective physical meanings by mathematical morphology’s multi-scale decomposition and this can reveal the local features of waves. Therefore, the transient current of ±800 kV UHVDC transmission lines, caused by the non-fault lightning stroke, fault lightning stroke and other line short circuit, can be decomposed by the multi-scale morphology decomposition to extract the spectral energy from the high and the low frequency bands, and the ratio of those two spectrum energy forms main criterion to realize the identification between lightening disturbance and the fault states. According to the ratio of the maximum of the current’s amplitudes of decomposition waveform of the first head of current’s second scale and sixth scale, to further distinguish the lightning stroke fault from the line short circuit. Extensive simulations show that the approach is correct and effective.

Abstract: The industrial development has been aggravating the atmospheric pollution increasingly. The pollution flashover has always been one of the most important problems that bother the development of electric power system in China. The key to prevent the happening of pollution flashover accident is that the electric power operation department can timely and correctly master the condition of external insulation of insulator string in operation to take measures before the happening of pollution flashover accident so as to prevent the happening of pollution flashover accident. The thesis introduces a set of pollution flashover voltage evaluation system for porcelain insulator which can anticipate the pollution flashover voltage of insulator and prevent the happening of the pollution flashover accident through monitoring the weather conditions such as the temperature and humidity, electric parameters such as the leakage current and circuit operating conditions such as the voltage class and type of insulator and considering their influences comprehensively. According to the set of pollution flashover evaluation system, we had a mass of tests in the thesis to fully verify the accuracy and reliability of this system that satisfy the requirement of electric power department.

Abstract: The objective of this paper is a generalization of printed media publications and publications of polymeric insulations’ manufacturers with a view to distinguish strengths and weaknesses of polymeric insulation, summarize experience in application of polymeric insulation and if possible to observe a tendency of its further development.

Abstract: With the increasing of the amount of composite insulators in power network, the transmission accidents caused by the fault of composite insulators are increased and the aging of composite insulators should be paying more attention. In the paper, fourier transform infrared spectroscopy (FTIR) is used to analysis the molecular structure of silicone rubber material of composite insulators. The results indicated that the higher the electric field of the insulator shed, the lower the peak of FTIR spectra. The heavier pollution the sample run, the lower the peak of FTIR spectra. So more attention should be pay to the samples which run in heavier pollution region or the high field part of the insulator.