Investigation of the Influence of Direct Current Bias on Transformer Vibration

2018 ◽  
Vol 19 (3) ◽  
Author(s):  
Jun Wang ◽  
Hongshun Liu ◽  
Kaicheng Niu ◽  
Zemin Wu
Keyword(s):  
Electrical Equipment ◽  
Safe Operation ◽  
Excitation Current ◽  
Transformer Substation ◽  
Direct Current Bias ◽  
Safety And Reliability ◽  
Variation Characteristics ◽  
Dc Bias ◽  
Simulation Results ◽  
Transformer Core

Abstract As a necessary electrical equipment for the construction of power grid, the safety and reliability of the transformer is the focus that people have always paid attention to. In recent years, the DC bias of the transformer has a serious impact on the safe operation of the power system, which has attracted wide attention of scholars at home and abroad. In view of this phenomenon, combined with the basic principle of transformer excitation, the simulation of the DC bias phenomenon is carried out by using Simulink software in this paper. According to the simulation results, the distortion characteristics of excitation current under DC bias are summarized. Then, based on the variation characteristics of excitation current under over excitation and DC bias, the law of transformer core vibration is deduced, and the cause of transformer abnormal vibration under DC bias is revealed. Finally, by analyzing the data of a transformer substation running under DC bias, it is found that the measured data are basically the same with our simulation results, which provides a basis and reference for further research on the phenomenon of transformer DC bias.

Analysis of Vibration and Noise in Transformer under DC Bias

2012 ◽  
Vol 229-231 ◽  
pp. 880-883 ◽  
Author(s):  
Bao Dong Bai ◽  
Jian Zhang ◽  
Guo Hui Yang ◽  
Jia Yin Wang
Keyword(s):  
High Harmonic ◽  
Comsol Multiphysics ◽  
Structural Stress ◽  
Safe Operation ◽  
Coupling Analysis ◽  
Current Generation ◽  
Finite Element Software ◽  
Field Coupling ◽  
Half Wave ◽  
Dc Bias

DC bias would cause the half-wave saturation of transformer, distortion of the exaction current, generation of high harmonic and the vibration and noise increases rapidly, which harm the safe operation of the transformers. In this paper, simulation of magnetic vibration and noise of a 160KVA dry-type transformer with DC bias and modal analysis with the finite element software comsol multiphysics is obtained. The software conduct multi-physical field coupling analysis to electric field, magnetic field, structural stress field and acoustic field, calculate the distribution of the noise and the natural frequency of transformer and propose effective measures to reduce the noise and vibration of transformer with DC bias.

scholarly journals Gm-Realization of Controlled-Gain Current Follower Transconductance Amplifier

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Worapong Tangsrirat
Keyword(s):  
Current Mode ◽  
Cmos Technology ◽  
Current Transfer ◽  
Biquad Filter ◽  
Transconductance Amplifier ◽  
Current Follower ◽  
Dc Bias ◽  
Simulation Results ◽  
Supply Voltages ◽  
A Current

This paper describes the conception of the current follower transconductance amplifier (CFTA) with electronically and linearly current tunable. The newly modified element is realized based on the use of transconductance cells (Gms) as core circuits. The advantage of this element is that the current transfer ratios (iz/ipandix/iz) can be tuned electronically and linearly by adjusting external DC bias currents. The circuit is designed and analyzed in 0.35 μm TSMC CMOS technology. Simulation results for the circuit with ±1.25 V supply voltages show that it consumes only 0.43 mw quiescent power with 70 MHz bandwidth. As an application example, a current-mode KHN biquad filter is designed and simulated.

The Technology Study of New Asymmetrical Half-Bridge Converter

2014 ◽  
Vol 986-987 ◽  
pp. 1884-1887
Author(s):  
Yue Fen Wu
Keyword(s):  
Theoretical Analysis ◽  
Control Strategy ◽  
Bridge Circuit ◽  
Technology Study ◽  
Soft Switch ◽  
Dc Bias ◽  
The Common ◽  
Simulation Results

Because the shortcomings of the common asymmetrical half-bridge circuit can't achieve soft switch and has DC bias for the transformer, the paper studies a new asymmetrical half-bridge circuit. Compared with the traditional asymmetrical half-bridge circuit, the circuit is added an auxiliary switch and diode by the composition of the slip. Thus the converter can achieve the control strategy of symmetric PWM. At last the simulation results show that the theoretical analysis is correct.

Value Oriented Engineering Solutions for Business Continuity

2021 ◽  
Author(s):  
Jose Luis Delgado Rivera
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Electrical Equipment ◽  
Business Continuity ◽  
Gas Industry ◽  
Holistic View ◽  
Emergency Situations ◽  
Business Operations ◽  
Safety And Reliability ◽  
Major Disruption

Abstract This paper presents a systemic approach using Engineering and analytics methods to avail the fastest and safest responses to recovering business operations after Abqaiq Plants major disruption after the 2019 September 14th incident. This new approach using value and agile engineering, risk management methodologies combined with the business continuity model suggested was successfully applied to recover Abqaiq Plants Operations after catastrophic events occurred. This paper pretends to serve as example about how the business continuity plan should response to a major emergency and how this planning activity could be effectively supported using a Value Oriented Engineering Solutions (VOES). This VOES approach is based on Business continuity framework and adapted for use during emergency situations to generate effective and urgent responses to recover one of the most strategical operations in the Oil and Gas Industry worldwide ahead of the last year significant disruption. VOES approach vastly implemented during Abqaiq Plants Restoration allowed a 100% functional recovery on 9 days, 5 days in advance to the most optimistic scenario. This paper shows a case study implemented for major instrumentation and electrical equipment activities performed in UA Spheroids plant, one of the most affected area and responsible to process the 100% of the Abqaiq Plants Oil Production rate. This paper pretends to contribute with the research and practice on business continuity management. Considering a particular approach to BCM, incorporating value-oriented engineering solutions in the developing of continuity plans; we apply model-based techniques to provide quality assurance in the elaboration process, and to automate the generation/update of a BCP. On the practical side, this study converts Operational, Maintenance, Safety and Reliability perspectives in a holistic view provided from Engineering solutions responsible to generate the guidelines for an agile, effective and realizable recovery plan.

Effect of Wheel-Rail Contact Geometry Relationship on Vehicle Dynamic Performance

2013 ◽  
Vol 712-715 ◽  
pp. 1541-1544
Author(s):  
Yi Jia Wang ◽  
Jing Zeng
Keyword(s):  
High Speed ◽  
Rapid Development ◽  
Dynamic Performance ◽  
Vehicle Dynamic ◽  
Safe Operation ◽  
Rail Wear ◽  
Variation Characteristics ◽  
Wheel Profile ◽  
Wheel Profile Wear ◽  
High Speed Vehicle

With the rapid development of high-speed railways, wheel and rail wear has become increasingly serious due to the acute wheel-rail interaction. During the operation of high speed vehicle, complicated wheel-rail contact force will lead to wheel profile wear, which will worsen the dynamic performance of vehicle system, or even influence the safe operation of vehicles. In order to ensure the vehicle dynamic performance, right now regularly wheel re-profiling has to be adopted. Therefore, the study of wheel profile wear and its effect on vehicle dynamic performance is very important [1,. The purpose of the paper is to study the variation characteristics of vehicle dynamic performance with respect to the wheel profile wear through numerical simulation and field test.

Design of Broadband GaN HEMT Power Amplifier with Ku Band

2012 ◽  
Vol 263-266 ◽  
pp. 39-42 ◽  
Author(s):  
Zhi Qun Cheng ◽  
Li Wei Jin ◽  
Wen Shi
Keyword(s):  
Output Power ◽  
Power Amplifier ◽  
Operating Conditions ◽  
Power Gain ◽  
Power Added Efficiency ◽  
Gan Hemt ◽  
Dc Bias ◽  
Simulation Results ◽  
Two Stages ◽  
Ku Band

A broadband power amplifier module based on GaN HEMT operating Ku band is designed. TGF2023-02 Chip of GaN HEMT from TriQuint is modeled first. And then the module consists of two stages amplifiers. The first stage amplifier is single-stage amplifier and the second is two-way combiner amplifier. Wilkinson power divider, DC bias circuits and microstrip matching circuits are simulated and designed carefully. Simulation results showed that the amplifier module exhibits a power gain of 7 dB, power added efficiency of 13.9%, and an output power of 16 W under Vds=28 V, Vgs=-3.6 V, CW operating conditions at the frequency of 15 GHz.

scholarly journals Influence of Electric Field Coupling Model on the Simulated Performances of a GaN Based Planar Nanodevice

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
K. Y. Xu ◽  
Z. N. Wang ◽  
Y. N. Wang ◽  
J. W. Xiong ◽  
G. Wang
Keyword(s):  
Electric Field ◽  
3D Model ◽  
Second Harmonic ◽  
Strong Electric Field ◽  
Three Dimensional ◽  
Harmonic Oscillation ◽  
Two Dimensional ◽  
Dc Bias ◽  
Simulation Results ◽  
2D Model

The performances of a two-dimensional electron gas (2DEG) based planar nanodevice are studied by a two-dimensional-three-dimensional (2D-3D) combined model and an entirely 2D model. In both models, 2DEGs are depicted by 2D ensemble Monte Carlo (EMC) method. However electric field distributions in the devices are obtained by self-consistently solving 2D and 3D Poisson equations for the 2D model and the 2D-3D model, respectively. Simulation results obtained by both models are almost the same at low bias while showing distinguished differences at high bias. The 2D model predicts larger output current and slightly higher threshold voltage of Gunn oscillations. Although the fundamental frequencies of current oscillations obtained by both models are similar, the deviation of wave shape from sinusoidal waveform obtained by the 2D model is more serious than that obtained by 2D-3D model. Moreover, results obtained by the 2D model are more sensitive both to the bias conditions and to the change of device parameters. Interestingly, a look-like second harmonic oscillation has been observed at DC bias. We contribute the origin of divergences in simulation results to the different coupling path of electric field in the two models. And the second-harmonic oscillations at DC bias should be the result of the appearance of concomitant oscillations beside the channel excited by strong electric-field effects.

Guide for Applying Codes and Standards for Safe Operation and Maintenance of Pressure Equipment in Refinery and Petrochemical Services

2010 ◽  
Author(s):  
John Reynolds
Keyword(s):  
National Standards ◽  
Process Industry ◽  
Consensus Building ◽  
Consensus Process ◽  
Safe Operation ◽  
Chemical Process Industry ◽  
Building Process ◽  
Safety And Reliability ◽  
New Construction ◽  
Service Inspection

After pressure equipment (aka fixed or static equipment) is designed, fabricated, and constructed to ASME new construction codes and standards (C/S), it is delivered and placed in-service. After that the In-service Inspection (ISI) and Post-Construction C/S begin to govern. Within the ASME, the Post Construction Committee (PCC) produces and maintains the standards that govern equipment after it has been placed inservice. Within the API Standards Organization, the Subcommittee on Inspection (SCI) and the Corrosion and Materials Subcommittee (CMSC) produce and maintain most of the ISI standards and recommended practices that govern pressure equipment in the refining and chemical process industry. This paper shows how many of those ISI and PCC C/S are intended to work together to maintain the safety and reliability of pressure equipment and piping after it has been placed in service. This paper also highlights what’s new with many of these C/S that have been recently updated or newly published. Both the API and ASME use the rigorous, standardized consensus building process outlined by the American National Standards Institute (ANSI) for formulating and publishing their respective C/S. This paper will show how users of these ISI/PCC codes and standards are benefited by the application of the ANSI consensus process.

Design of the System for Online Monitoring Dielectric Loss

2012 ◽  
Vol 472-475 ◽  
pp. 1568-1571
Author(s):  
Jian Feng Zheng ◽  
Hao Qiang
Keyword(s):  
Dielectric Loss ◽  
Monitoring System ◽  
High Voltage ◽  
Online Monitoring ◽  
Electrical Equipment ◽  
Comparison Method ◽  
Zero Crossing ◽  
Transformer Substation ◽  
Online Monitoring System ◽  
Upper Computer

For knowing the dielectric loss of high-voltage capacitive electrical equipment timely and mastering the electrical insulation of high voltage equipment effectively to ensure the reliable operation of these voltage equipments, an online monitoring system is designed in this paper based on the practical project. The system is made up of two parts including lower computer and upper computer. Using the microcontroller C8051F023 as the core of the lower computer and adopting an improved zero-crossing comparison method, the measurement of dielectric loss is realized and the data are sent to upper computer by wireless way. SQL2000 is used in the upper computer for data management, which can be real-time displayed, inquired and printed in report forms. At present, this monitoring system has successfully applied in the Houqiao 330 kV transformer substation in Ningxia. The operating results show that the system can meet well the online monitoring demand of the high voltage capacitive electrical equipment.

Sign in / Sign up

Export Citation Format

Share Document