Research on Electrical Characteristics of a Novel Balance Transformer with Asymmetrical Winding

2014 ◽  
Vol 536-537 ◽  
pp. 1523-1526 ◽  
Author(s):  
Yong Sheng Li ◽  
Yi Fa Sheng ◽  
Kai Yi Zhang ◽  
Bo Fan
Keyword(s):  
Magnetic Force ◽  
Short Circuit ◽  
Neutral Current ◽  
Force Balance ◽  
Analysis Method ◽  
Systematic Analysis ◽  
Negative Sequence ◽  
Transfer Equations ◽  
Zero Sequence ◽  
Negative Sequence Current

For problems of zero sequence current and negative sequence current of traction transformer in Electrified Railway, a novel balance transformer with asymmetrical windings was presented. By a systematic analysis method based on the magnetic force balance equations, winding connection equations, output-port equations and voltage transfer equations, the current relationships of the primary windings and secondary windings, the balance condition and the short circuit impedances (when the neutral current in the primary side is zero) were deduced, and the electric characteristics of the balance transformer was analyzed. Through the experimental model of balance transformer in simulation platform based on Matlab/Simulink, the electric characteristics of balance transformer and change law of zero sequence current and negative sequence current in different mode were researched. Correctness and feasibility of the theoretical analysis are verified through the simulation experiment.

Research on a Novel Balance Transformer with Asymmetrical Windings

2014 ◽  
Vol 915-916 ◽  
pp. 1149-1152 ◽  
Author(s):  
Chu Zhu ◽  
Yong Sheng Li
Keyword(s):  
Magnetic Force ◽  
Simulation Experiment ◽  
Force Balance ◽  
Analysis Method ◽  
Balance Equations ◽  
Systematic Analysis ◽  
Negative Sequence ◽  
Transfer Equations ◽  
Zero Sequence ◽  
Negative Sequence Current

For problems of zero sequence current and negative sequence current of traction transformer in Electrified Railway, a novel balance transformer with asymmetrical windings was presented. By a systematic analysis method based on the magnetic force balance equations, winding connection equations, output-port equations and voltage transfer equations, the current relationships of the primary windings and secondary windings and the balance condition were deduced. Through the experimental model of balance transformer in simulation platform based on Matlab/Simulink, the electric characteristics of balance transformer and change law of zero sequence current and negative sequence current in different mode were researched. Through the simulation experiment, the theoretical analysis of correctness and feasibility are verified.

scholarly journals Non-Directional Earth Fault Passage Indication in Isolated Neutral Distribution Networks

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4732
Author(s):  
Amir Farughian ◽  
Lauri Kumpulainen ◽  
Kimmo Kauhaniemi
Keyword(s):  
Single Phase ◽  
Distribution Networks ◽  
Voltage Measurement ◽  
Negative Sequence ◽  
Overhead Lines ◽  
New Methods ◽  
Zero Sequence ◽  
Isolated Neutral ◽  
Negative Sequence Current ◽  
Symmetrical Sequence

In this paper, two new methods for locating single-phase to ground faults in isolated neutral distribution networks are proposed. The methods are based on the analysis of symmetrical sequence currents. They are solely based on currents, not requiring voltage measurement. The first method employs only the zero sequence current and the second one utilizes the negative sequence current in combination with the zero sequence current. It is revealed why using only zero sequence current with a simple threshold is insufficient and may lead to false results. Using the proposed methods, earth faults with high resistances can be located in isolated neutral distribution networks with overhead lines or cables.

scholarly journals Induction Motor Stator Interturn Short Circuit Fault Detection in Accordance with Line Current Sequence Components Using Artificial Neural Network

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Gayatridevi Rajamany ◽  
Sekar Srinivasan ◽  
Krishnan Rajamany ◽  
Ramesh K. Natarajan
Keyword(s):  
Neural Network ◽  
Fault Detection ◽  
Induction Motor ◽  
Short Circuit ◽  
Positive Sequence ◽  
Negative Sequence ◽  
Three Phase ◽  
Sequence Components ◽  
Negative Sequence Current ◽  
Short Circuit Fault

The intention of fault detection is to detect the fault at the beginning stage and shut off the machine immediately to avoid motor failure due to the large fault current. In this work, an online fault diagnosis of stator interturn fault of a three-phase induction motor based on the concept of symmetrical components is presented. A mathematical model of an induction motor with turn fault is developed to interpret machine performance under fault. A Simulink model of a three-phase induction motor with stator interturn fault is created for extraction of sequence components of current and voltage. The negative sequence current can provide a decisive and rapid monitoring technique to detect stator interturn short circuit fault of the induction motor. The per unit change in negative sequence current with positive sequence current is the main fault indicator which is imported to neural network architecture. The output of the feedforward backpropagation neural network classifies the short circuit fault level of stator winding.

scholarly journals Earth Fault Location Using Negative Sequence Currents

Energies ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3759 ◽  
Author(s):  
Farughian ◽  
Kumpulainen ◽  
Kauhaniemi
Keyword(s):  
Fault Location ◽  
Single Phase ◽  
Distribution Networks ◽  
Practical Implementation ◽  
Negative Sequence ◽  
Medium Voltage ◽  
Different Types ◽  
Sequence Components ◽  
Zero Sequence ◽  
Negative Sequence Current

In this paper, a new method for locating single-phase earth faults on non-effectively earthed medium voltage distribution networks is proposed. The method requires only current measurements and is based on the analysis of the negative sequence components of the currents measured at secondary substations along medium voltage (MV) distribution feeders. The theory behind the proposed method is discussed in depth. The proposed method is examined by simulations, which are carried out for different types of networks. The results validate the effectiveness of the method in locating single-phase earth faults. In addition, some aspects of practical implementation are discussed. A brief comparative analysis is conducted between the behaviors of negative and zero sequence currents along a faulty feeder. The results reveal a considerably higher stability level of the negative sequence current over that of the zero sequence current.

A Study on DG Control Strategy and Grid Protection

2014 ◽  
Vol 521 ◽  
pp. 204-212
Author(s):  
Xin Chao Wang ◽  
Chen Xin Yang
Keyword(s):  
Load Capacity ◽  
Short Circuit ◽  
Current Source ◽  
Islanding Detection ◽  
Test Results ◽  
Total Load ◽  
Line Voltage ◽  
Negative Sequence ◽  
Three Phase ◽  
Negative Sequence Current

DG integration reduces the selectivity and sensitivity of grid relay protection. A new control algorithm is proposed. It shows that the negative sequence current will not be affected by DG when the DG is designed as a symmetric three-phase current source. In this case, the negative sequence characteristic can be utilized for grid protection during short-circuit faults. If DGs maximum power capacity is restricted to be lower than total load capacity, DG terminal line-voltage and the negative sequence voltage can be used as the criteria for islanding detection. Then it is possible to cutoff DG in order to fulfill the reclosing requirement. A complicated simulation system is designed using PSCAD/EMTDC program. Different short-circuit faults are simulated to verify the proposals. The test results confirm well with the conclusions.

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