Advanced Materials Research Vols. 960-961

Abstract: The fault current limit technology based on the principle of permanent-magnet-biased saturation has several outstanding advantages in both economy and technology. A modeling method of PMFCL based on the finite element analysis platform – Maxwell is presented in this paper. The current limiting mechanism of line-type PMFCL is analyzed, on the basis of which the 2D and 3D models are established in Maxwell, and the corresponding experiments are designed as well. Comparisons between the simulation and experimental results indicate that the modeling method is reasonable. Research achievements of this paper provides theoretical basis for further studies of PMFCL.

Abstract: Analysis the 500kV H-GIS equipment failure, determine for the circuit breaker chamber internal discharge fault according to the protection action and the use of the analysis of SF₆ gas composition, a detailed analysis of the possible causes of failures, and according to the disintegration test results, to confirm the final reason for internal foreign bodies caused by discharge. Finally, put forward some prevention measures and suggestions for the accident.

Abstract: The theoretical analysis and numerical simulation of electron beam generation in foil-less diode are presented. The theories of OAL, CL, and equilibrium beam model are briefly compared. All the theoretical models can give a relatively accurate solution of electron gun, and the equilibrium beam model is more appreciated. A PIC simulation tool UNIPIC is introduced and is used to analyze the behaviors of a foil-less diode. Under the conditions of 180 kV incident voltage wave and 2.5 T axial magnetic fields, we obtained the 250 kV, 1.5 kA output beam current which can be used in high power microwave generators.

Abstract: In this article, a portable XLPE cable insulation detection device is introduced. Such a device utilizes electromagnetic coupling, UHF electromagnetic wave and acoustic emission to detect partial discharge signals in power cables. By analyzing the partial discharge signals and cable temperatures, the insulation status of XLPE power cables is judged.

Abstract: To suppress the stochastic pulse interference in XLPE Cables, this paper uses equivalent time-frequency method to extract pulse feature values, adaptive fuzzy clustering to classify pulses, phase concentration as an index to distinguish PD and stochastic pulses. Analysis results of on-site data show that this method can effectively suppress stochastic pulse interference in the PD signal, providing a useful theoretical and practical basis to assess the state of XLPE cable insulation.

Abstract: Ultra-high voltage (UHV) projects are making power system growing lager and resulting in sharp increase of short circuit currents in some area especially in the vicinity of UHV access points. The paper presented the damage of short circuit current increases and common methods to limit fault current. Taking the construction and development of UHV grid in a province of central China as background, the over short circuit currents in 500kV Grid within UHV were showed and several countermeasures including choosing proper UHV access scheme, implementing UHV substation lower voltage bus partition running, installing reactors, optimizing power grid network based on UHV connection point were proposed and then verified by PSASP simulation. The results show those measures are useful to reduce the short circuit current to a reasonable level.

Abstract: In order to improve the diagnosis method of the existing high-voltage circuit breaker fault, demonstrated a new diagnosis methord of mechanical failure of high voltage circuit breaker based on vibration signal. According to the factors of high voltage circuit breaker failure and the features of Single-hidden Layer Feedforward Neural Network, SLFN, a method of high voltage circuit breaker fault diagnosis proposed based on Extreme Learning Machine (ELM). Finally, the experiment proves the effectiveness of this method for breaker fault diagnosis based on vibration signal analysis and ELM.

Abstract: Mechanical failure of high voltage circuit breaker accounted for the largest percentage of, it is necessary to diagnosis the mechanical fault .The acoustic signal of high voltage circuit breaker contains a large number of mechanical state information, can put the acoustic signal characteristics as a basis for high voltage circuit breaker fault diagnosis. M - RVM expanding traditional RVM to multiple categories, very suitable for fault diagnosis of high voltage circuit breaker.In this paper, the M-RVM combined with EEMD method for high voltage circuit breaker mechanical fault diagnosis, the experimental results show that the method has a good diagnosis effect.

Abstract: High voltage circuit breaker's motion parameters of the moving contact is one of the key performance indicators in the evaluated of breaker. By means of extracting color features of LW10B-252 circuit breaker by image segmentation, then determining its center point of the minimum circumscribed rectangle, getting the movement distance of center point and the use of time in adjacent images, realization motion parameter's measurement of the moving contact. This paper presents a algorithm based on improved k-means clustering algorithm to extract the color characteristics of the mechanical linkage of breaker, at the same time contrast with classical OTSU method and RGB color segmentation method. Experimental results show that the k-means clustering algorithm have a better segmentation result.

Abstract: This paper presents a new csi-hvusspwm technology with many advantages such as the better output waveforms and the high utilization ratio of dc voltage based on the study of the csi-spwm technology and csi-tpwm technology. Theoretical derivation and modulation principle of csi-hvusspwm technology are described in detail. Finally, the simulation results validate the feasibility and effectiveness of this novel technology.