The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized...
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ISBN:
(纸本)9781627480000
The paper presents the measurement results of the noise level of a power transformer. The noise sources occurring in the transformer are presented, and the method applied and the measuring tools used are characterized. The measurements were taken in 29 points located around the transformer. The evaluation of noise was carried out based on the revised coefficient of the acoustic pressure level. The research work results presented enable the evaluation of the influence of the noise of the unit under study on its environment and make it easier to diagnose the degrees of wear of the fans installed in transformer coolers.
The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power statio...
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ISBN:
(纸本)9781627480000
The paper will present the wavelet analysis results using continuous and discrete wavelet transforms of vibrations of a power transformer tub installed on the block of a conventional, thermal condensation power station. The research tests were carried out during a regular transformer operation in industrial conditions. The measurements were taken from the point of view of the evaluation of the influence of the vibrations registered on the analysis results of the acoustic emission signals generated by partial discharges that can occur in paper-oil insulation systems of power transformers. Moreover, the analyses carried out were supplemented with the research results obtained in laboratory conditions during the measurements taken in the high-voltage testing station of high-voltage power appliances. The influence of the loosened screws fastening the lid of the transformer tub on the time-frequency analysis results obtained of the vibrations registered was investigated. Moreover, the range of the research work carried out referred to the evaluation of the influence of the changes of the pressure force of the metal plates forming the transformer core on the vibration measurement results were obtained. In summary, the evaluation of usefulness was presented and the range of the time-frequency analysis application possibilities, and especially wavelet transforms, in diagnostics of power transformers using the acoustic methods was characterized.
In electrical power systems, the coordination of protections in time domain is important and difficult problem. The time settings of protection relays have to be adapted to the time characteristics of electrical power...
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Based on the property of Human vision system (HVS) that human eye's sensitivity to an image varies with different information regions of the image, Pulse-coupled neural network (PCNN) model is modified for image s...
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Based on the property of Human vision system (HVS) that human eye's sensitivity to an image varies with different information regions of the image, Pulse-coupled neural network (PCNN) model is modified for image segmentation. The modified PCNN stimulated by an input image has pulse output with multiple pulse values rather than only two in the conventional PCNN, according to the local information rate of the input image. This results in image segmentation according to local information rate delivered from the image by the modified PCNN. Experiments with the modified PCNN on image segmentation and image compression on the segmented images with the principle that the lower information rate is, the higher compression rate is applied, show much better performance in compression rate compared with that on the segmented images with the conventional PCNN.
In this paper, a design of the 3-phase, 6-stator-pole and 4-rotor-pole, 15 kW switched reluctance motor for the propulsion system of the electric vehicle is presented. Its performance such as the torque per volume and...
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ISBN:
(纸本)8986510081
In this paper, a design of the 3-phase, 6-stator-pole and 4-rotor-pole, 15 kW switched reluctance motor for the propulsion system of the electric vehicle is presented. Its performance such as the torque per volume and its efficiency are compared to the machine which is designed based on the conventional design guideline.
In this paper a method to estimate the initial rotor position of the switched reluctance motor (SRM) at the stand still condition is proposed. The proposed method can be implemented by the simple microcontroller based...
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ISBN:
(纸本)8986510081
In this paper a method to estimate the initial rotor position of the switched reluctance motor (SRM) at the stand still condition is proposed. The proposed method can be implemented by the simple microcontroller based system, and it is not necessary to know the magnetization curves. The impulse gate drive signal is applied and the winding current is detected and its approximate value is used for calculating the rotor position. The compensation method to reduce the estimation error thorough one cycle is also mentioned. The proposed method is implemented with the 6-stator-pole and 4-rotor-pole, 1.5 kW 3-phase switched reluctance motor.
This paper presents an analysis how the pulses in the long three-conductor coupled lines with common screen interact mutually. The interaction of pulses appears in those places of the line, where there is a change in ...
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This paper presents an analysis how the pulses in the long three-conductor coupled lines with common screen interact mutually. The interaction of pulses appears in those places of the line, where there is a change in characteristic impedance causing a change in reflection coefficient for pulses moving along the line. An exemplary analysis is conducted for a homogenous lossless line both at its starting and terminal point. The results of the analysis are analytical expressions describing quantitative interactions of pulses. The expressions are verified numerically and experimentally involving measurements of the real-life line. The mutual interaction of pulses can be useful in location of faults in electric power lines by means of the pulses method.
The paper deals with the electromagnetic torque computations in models of rotating electrical machines utilizing the Lagrange sliding surface technique for rotor movement representation. Various interpolating function...
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The paper deals with the electromagnetic torque computations in models of rotating electrical machines utilizing the Lagrange sliding surface technique for rotor movement representation. Various interpolating functions are tested to construct a coupling algorithm for moving and stationary regions. Two different formulas for torque calculation are used. The error in torque computations is assessed using two models of induction machines. The reference models are those of the same machines but applying the moving band technique. The best interpolation algorithm is found from the analysis and its accuracy is assessed by comparison with other algorithms. The analysis is carried out under assumption of uniformly distributed nodes at the sliding interface and is addressed to two-dimensional finite element models based on first order approximation.
Since eutrophication has become increasingly severe in China,nitrogen and phosphorous have been the concern of wastewater treatment,especially nitrogen *** stabilization of the intelligent control system and nitrogen ...
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Since eutrophication has become increasingly severe in China,nitrogen and phosphorous have been the concern of wastewater treatment,especially nitrogen *** stabilization of the intelligent control system and nitrogen removal efficiency were investigated in a pilot-scale aerobic-anoxic sequencing batch reactor(SBR)with a treat-ment capacity of 60 m3/*** points on the profiles of dissolved oxygen(DO),pH,and oxidation reduction potential(ORP)could exactly reflect the process of nitrifica-tion and *** the intelligent control system not only could save energy,but also could achieve advanced nitrogen *** the control strategy water quality of the effluent could stably meet the national first discharge standard during experiment of 10 *** at low tem-perature(t=13°C),chemical oxygen demand(COD)and total nitrogen(TN)in the effluent were under 50 and 5 mg/L,respectively.
In electrical power systems, the coordination of protections in time domain is important and difficult problem. The time settings of protection relays have to be adapted to the time characteristics of electrical power...
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In electrical power systems, the coordination of protections in time domain is important and difficult problem. The time settings of protection relays have to be adapted to the time characteristics of electrical power system plants and the delay times of the other protections. In the paper, Fault Trees with Time Dependencies (FTTDs) are used in selection of values of the delay times of primary (local) and remote backup protections. In the FTTD, events and gates are characterized by time parameters. These time parameters are derived from the time characteristics of protection devices and the inherent delay times of protection equipment.
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