A New Method for Faulted Line Identification in Neutral Non-Grounded Distribution Systems

2011 ◽  
Vol 383-390 ◽  
pp. 2496-2500
Author(s):  
Dan Li ◽  
Fang Zong Wang
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Distribution Systems ◽  
Single Phase ◽  
Short Circuit ◽  
Difficult Problem ◽  
New Method ◽  
Vacuum Switch ◽  
Line Identification ◽  
Simulation Results

It is well-known that, the identification of the single-phase to ground faulted line in neutral non-grounded distribution systems is a difficult problem, due to its very small faulted current. This paper proposes a new method for the solution of this problem. The principle of the proposed method is to convert the neutral non-grounded system into a neutral grounded system temporarily by using a triggered vacuum switch based controllable short-circuit equipment. By time-domain numerical simulation, the proposed method is evaluated, and the simulation results have shown the effectiveness of the proposed method.

Numerical Simulation by CGM for Moving Force Identification

2012 ◽  
Vol 238 ◽  
pp. 826-829
Author(s):  
Zhen Chen ◽  
Jun Ling Han
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Bending Moment ◽  
Identification Accuracy ◽  
Time Varying ◽  
Acceptable Solution ◽  
Moving Force ◽  
Ill Posed ◽  
Simulation Results ◽  
The Time Domain

The conjugate gradient method (CGM) is compared with the time domain method (TDM) in the paper. The numerical simulation results show that the CGM have higher identification accuracy and robust noise immunity as well as producing an acceptable solution to ill-posed problems to some extent when they are used to identify the moving force. When the bending moment responses are used to identify the time-varying loads, the identification accuracy is more obviously improved than the TDM, which is more suitable for the time-varying loads identification.

A Theoretic Analysis Method Research of Load Appling Based on Response Control in Time Domain

2013 ◽  
Vol 432 ◽  
pp. 341-344
Author(s):  
Jie Hu
Keyword(s):  
Numerical Simulation ◽  
Time Domain ◽  
Product Performance ◽  
New Method ◽  
Analysis Method ◽  
Theoretic Analysis ◽  
Response Control ◽  
Duhamel Integral

With the discretely analysis of Borel theorem and Duhamel integral, a new theoretic analysis method of load appling with the purpose of time domian response control is proposed. Result of numerical simulation indicated the validity of this new method, the research of this paper provided an effective way of time domain load applying in examing the product performance.

scholarly journals Comparison of Models of Single-Phase Diode Bridge Rectifiers for Their Use in Harmonic Studies with Many Devices

Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 66
Author(s):  
Tatiano Busatto ◽  
Sarah K. Rönnberg ◽  
Math H. J. Bollen
Keyword(s):  
Numerical Simulation ◽  
Computational Complexity ◽  
Time Domain ◽  
Single Phase ◽  
Low Voltage ◽  
Level Of Detail ◽  
Trade Off ◽  
Current Harmonics ◽  
Voltage Distortion ◽  
Conduction Mode

Harmonic modeling of low-voltage networks with many devices requires simple but accurate models. This paper investigates the advantages and drawbacks of such models to predict the current harmonics created by single-phase full-bridge rectifiers. An overview is given of the methods, limiting the focus to harmonic analysis. The error of each method, compared to an accurate numerical simulation model, is quantified in frequency and time domain considering realistic input scenarios, including background voltage distortion and different system impedances. The results of the comparison are used to discuss the applicability of the models depending on the harmonic studies scale and the required level of detail. It is concluded that all models have their applicability, but also limitations. From the simplest and fastest model, which does not require a numerical solution, to the more accurate one that allows discontinuous conduction mode to be included, the trade-off involves accuracy and computational complexity.

scholarly journals Experimental and simulated milling stability tests

Mechanik ◽  
2017 ◽  
Vol 90 (11) ◽  
pp. 965-967
Author(s):  
Piotr Andrzej Bąk ◽  
Krzysztof Jemielniak
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Time Domain ◽  
Cutting Parameters ◽  
Milling Machine ◽  
Machined Surface ◽  
Simulation Results ◽  
The Stability ◽  
The Time Domain

Self-excited vibrations significantly reduce the milling productivity, deteriorate the quality of machined surface and tool life. One of the ways to avoid these vibrations is to modify the cutting parameters based on the stability analysis results. A method of numerical simulation of self-excited vibrations in the time domain can be used for this purpose. A comparison of numerical simulation results with those from experiments conducted using a milling machine is presented. The results confirm the correctness of applied modeling.

Numerical Simulation of the Transient Flow in a Pump-Turbine During the Load Rejection Process With Special Emphasis on the Cavitation Effect

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Xiaolong Fu ◽  
Deyou Li ◽  
Hongjie Wang ◽  
Guanghui Zhang ◽  
Zhenggui Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Single Phase ◽  
Pressure Pulsation ◽  
Phase Flow ◽  
Cavitation Flow ◽  
Single Phase Flow ◽  
Pump Turbine ◽  
Cavitation Effect ◽  
Simulation Results ◽  
Load Rejection Process

Abstract At present, pumped-storage power technology is the only available and effective way for the load balancing and energy storage in the grid network scale. During the frequent switch back and forth conditions, there are severe pressure pulsation and cavitation in pump-turbines. However, their generation mechanism has not been determined yet. This work contributes to the numerical simulation of the transient behaviors in a prototype pump-turbine during the load rejection process with special emphasis on cavitation effect. In this study, the two-dimensional dynamic remesh and variable speed slide mesh methodologies were employed to perform the simulation of the transient single-phase flow and cavitation flow in a pump-turbine. The simulation results of single-phase flow and cavitation flow were both consistent with the experimental data except in local regions based on the experimental validation of prototype tests. However, the numerical results considering cavitation effects have a better behavior than those of single-phase flow in the predictions of pressure pulsation and rotational speed. Then, the cavitation flow simulation results were analyzed deeply, especially in pressure pulsation and cavitation flow field. Analysis revealed that three typical complex frequency components of pressure were captured in the cavitation flow, which significantly affect the axial hydraulic thrust on the runner. And it is validated that they are primarily induced by the cavity collapse near the trailing edges of the runner blades in reverse pump mode and the interaction between cavitation and vortex rope in draft-tube in turbine mode.

Sensitivity of Induction Motor under Symmetrical Voltage Sags and Interruption

2014 ◽  
Vol 875-877 ◽  
pp. 1923-1928 ◽  
Author(s):  
Surya Hardi ◽  
Ismail Daut ◽  
Ismail Rohana ◽  
Muhd Hafizi
Keyword(s):  
Power Systems ◽  
Distribution Systems ◽  
Single Phase ◽  
Induction Motors ◽  
Short Circuit ◽  
Inrush Current ◽  
Voltage Sags ◽  
Three Phase ◽  
Nominal Voltage ◽  
Transmission And Distribution

Voltage sags and interruption are one of most important of power quality problems. They can influence performance of equipment such as induction motors. They are generally caused by short circuit faults in transmission and distribution systems which propagate in entire of power systems. When their appear at a motor terminal, its effects are the speed and the torque will decrease to a level lower than values of the normal and even the motor become stall if magnitude of the voltage sags and duration exceed certain limit. The voltage can return to nominal voltage after end of the voltage sag and interruption. The motor will experience re-acceleration to normal condition is accompanied by large inrush current. A study on induction motors was carried out to confirm these effects. Single-phase and three-phase of small induction motors were used for investigating the effects caused by symmetrical voltage sags and interruption through experimental and simulation.

Induction Motor Fault Diagnosis Using Voltage Spectrum of Auxiliary Winding and Lissajous Curve of its Park Components

2013 ◽  
Vol 805-806 ◽  
pp. 963-979 ◽  
Author(s):  
Lamiaâ El Menzhi ◽  
Abdallah Saad
Keyword(s):  
Fourier Transform ◽  
Fault Diagnosis ◽  
Frequency Domain ◽  
Induction Motor ◽  
Discrete Fourier Transform ◽  
Time Domain ◽  
New Method ◽  
Spectrum Simulation ◽  
Simulation Results ◽  
The Time Domain

In this paper, a new method for induction motor fault diagnosis is presented. It is based on the so-called an auxiliary winding voltage and its Park components. The auxiliary winding is a small coil inserted between two of the stator phases. Expressions of the inserted winding voltage and its Park components are presented. After that, discrete Fourier transform analyzer is required for converting the signals from the time domain to the frequency domain. A Lissajous curve formed of the two Park components is associated to the spectrum. Simulation results curried out for non defected and defected motor show the effectiveness of the proposed method.

Lissajous Curve of an Auxiliary Winding Voltage Park Components for Diagnosing Induction Motor Inverter Defects

2014 ◽  
Vol 1008-1009 ◽  
pp. 1039-1051 ◽  
Author(s):  
Lamiaâ El Menzhi ◽  
Abdallah Saad
Keyword(s):  
Mathematical Model ◽  
Fault Diagnosis ◽  
Induction Motor ◽  
Time Domain ◽  
New Method ◽  
Voltage Inverter ◽  
Three Phase ◽  
Simulation Results

In this paper, a new method for voltage inverter feeding induction motor fault diagnosis is presented. It is based on the so-called the Lissajous curve of an auxiliary winding voltage Park components. For this purpose, time domain mathematical model of a three phase induction motor fed by an inverter and expressions of the inserted winding voltage and its Park components are presented. Simulation results curried out for non defected and defected inverter show the effectiveness of the proposed method.

Lissajous Curve of an Auxiliary Winding Voltage Park Components for Doubly-Fed Induction Machine Electrical Faults Diagnosis

2013 ◽  
Vol 860-863 ◽  
pp. 2223-2231 ◽  
Author(s):  
Lamiaâ El Menzhi ◽  
Abdallah Saad
Keyword(s):  
Mathematical Model ◽  
Time Domain ◽  
Induction Machine ◽  
New Method ◽  
Three Phase ◽  
Doubly Fed Induction Machine ◽  
Faults Diagnosis ◽  
Simulation Results ◽  
Electrical Faults ◽  
Doubly Fed

In this paper, a new method for doubly-fed induction machine electrical faults diagnosis is presented. It is based on the so-called the Lissajous curve of an auxiliary winding voltage Park components. For this purpose, time domain mathematical model of a three phase doubly-fed induction machine and expressions of the inserted winding voltage and its Park components are presented. Simulation results curried out for non defected and defected machine show the effectiveness of the proposed method.

scholarly journals Digital technologies for monitoring and implementation of smart diagnostics of the isolation of power supply systems with isolated neutral in the operating mode

2021 ◽  
Vol 75 (2) ◽  
pp. 109-112
Author(s):  
N.P. Kondrateva ◽  
A.A. Shishov ◽  
R.G. Bolshin ◽  
M.G. Krasnolutskaya
Keyword(s):  
Power Supply ◽  
Power Distribution ◽  
Distribution Systems ◽  
Power Supply System ◽  
Single Phase ◽  
Short Circuit ◽  
Digital Technologies ◽  
Operating Mode ◽  
Supply System ◽  
Ground Faults

Nowadays, 75% of emergencies at power supply facilities are caused by single-phase ground faults. The currently used methods of thermal imaging and ultrasonic testing do not allow accurately identify the cause of accidents in electric power distribution systems. The current search generators, due to their low power, cannot cover the entire section of the diagnosed network. The article suggests the use of digital technologies for the intelligent diagnostics of the insulation of power supply system with insulated neutral in the operating mode, allowing on-line diagnostics of the network and analyzing the data obtained for the early prevention of emergency situations. In order to avoid disconnecting sections and diagnose the system in operating mode, it is proposed to check the system using a currentlimiting capacitor, which will be connected to the live parts of each phase under voltage and accurately determine the location of a single-phase short circuit for any number of feeders. The relevance of these studies is due to the fact that, for example, during two years at one of the manufactures 19 emergencies related to single-phase ground faults were recorded. Four of these cases led to a complete stop of the production. Therefore, the development of digital technologies for the implementation of smart diagnostics of the insulation of an energized power supply system with insulated neutral will be of interest to practitioners, scientists, researchers, graduate students and other specialists seeking to study the latest achievements in smart agribusiness for their subsequent application in the real world.

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