Papers by Keyword: Transformer

Abstract: This research presents a time series analysis and artificial neural network (ANN)-based scheme for fault diagnosis of power transformers, which extracts the characteristic parameters of the faults of the transformer from the results of time series analysis and bases on this basis establishes the corresponding back propagation (BP) neural network to detect the transformer operating faults. The simulation experimental results show that as compared to the related works, the proposed approach effectively integrates the superiority of time series analysis and BP neural network and thus can greatly improve the diagnosis accuracy and reliability.

Abstract: In this paper, a new method using wavelet packet energy spectrum to identify transformer inrush and internal fault current was proposed. Wavelet packet transform respectively decomposed inrush and fault current, then calculated the energy of each frequency band of decomposed signal. Finally, the conclusion showed that the energy of internal fault in high frequency band is much less than that of inrush. The difference was quantified and it could be observed intuitively. Through extensive simulations, this paper proves that the method in terms of identifying transformer inrush is accurate and effective.

Abstract: In the domestic certification bodies the automation degree of the definitive test of the accessories products left much to be improved, as for safety of the transformer conforming to the international standard of IEC61558-1, the traditional manual testing method barely meets the requirements of sampling rate, and has caused a lot of technical deficiencies including inadmissible deviation in the calculation and post-processing of the related experimental data, lengthy work-time of staff, and low test efficiency. In this paper, concerning the type test of various electronic and power transformers, a set of intelligent automatic measurement and control system of the temperature rise test is presented, consisting of software packages with modularized designing and an original hardware apparatus with built-in control modules. Therefore this system is capable of performing a series of operations without human intervention, such as controlling of the related testing equipment, data analysis, real-time monitoring, timing acquisition and data processing of corresponding algorithms, auto-save of test configuration and generating original record of the test. Thus, the idea of ‘Full automation with only one simple configuration’ has truly been realized. The experimental results show that compared with the traditional testing method, the application of this system minimized uncertainty caused by human factors in the testing process and improve precision of data analysis, and also ensured the reproducibility, consistency and traceability of the test results effectively.

Abstract: The author used CFD software to simulate when group panel-type radiator quantity, space, height of gooseneck have changed, how temperature distribute on the radiator. To obtain when group panel-type radiator quantity, space, height of gooseneck and other factors have changed, the laws of heat transfer efficiency changed and analyzed the reasons for emergence of such laws in theory. The optimal group of panel-type radiator improvement program is explored, to provide guidance for the practical application of engineering.

Abstract: The transformer rated secondary load in electric energy metering device was much larger before electric energy metering device revamp. Big energy differences exist before and after the revamp. The reason of making down rated secondary load and its influence on transformer error and energy metering are analyzed in the presented work.

Abstract: Traction transformers areheavy and suffering dynamic load all the time when the train is starting,stopping and moving. These load cases make it necessary to design tractiontransformers in fatigue resistance view. In this paper, random vibrationsimulation is done for traction transformer with finite element method. ThisFEM result is used for fatigue analysis. Several methods of damage accumulationfor random vibration are discussed and compared with test result. Result showssingle moment method is a better choice for traction transformers.

Abstract: Both the cost-effective operation of power systems and reliable operation are inextricably linked with the transformer life assessment. This paper analyzes the composition of the transformer life, life assessment factors and existing assessment methods. Based on factors of the current life assessment and problems of assessment methods, the paper analyzed the importance significance of uncertainty in the transformer life assessment and proposed the transformer remaining life assessment model, and methods based the random fuzzy theory. Assessment results can provide the basis for the transformer maintenance and help safe and economic operation of power systems.

Abstract: This paper reviews kinds of 110kV transformer percentage restraint differential protection’s principles from differential types and different manufacturers. Based on the Adobe AIR cross-platform technology, a new system on mobile terminal is carried out to support kinds of transformer protections’ calibration in one auxiliary application. On Android platform and iOS platform, this system is able to calculate testing currents, predict actual action boundary points and draw restraint characteristic curve. All the functions improve calibration efficiency and logic verification reliability greatly.

Abstract: Medium voltage in the electric power system of ship typically is powered by a large capacity transformer for low voltage electrical apparatus. When switching on, the primary side of transformer will produce very large current, which would endanger the safe operation of power for ships. The mechanism and characteristics of magnetizing inrush current is analyzed when the transformer switches with no load. We think that the reason caused magnetizing inrush current is transformers saturation. Pre-excitation is presented through a small volume transformer magnetizing method of suppressing the inrush current of transformer and validated by simulation and experiment.

Abstract: Many error abnormities and verification difficulties appear in high voltage transformer field error tests. Field verification is with site and duration limit, so it is important to timely solve problems and complete tests. Field practical problems and solutions are expounded through technical analysis for technicians in the presented work.