Internal Fault Currents in Multicircuit Induction Machines [includes discussion]

1954 ◽  
Vol 73 (2) ◽  
Author(s):  
D. L. Lafuze
Keyword(s):  
Induction Machines ◽  
Fault Currents ◽  
Internal Fault

Impact of supply voltage variations on external magnetic field emitted by induction machines

2017 ◽  
Vol 36 (3) ◽  
pp. 692-701
Author(s):  
Mohamed Omar Younsi ◽  
Olivier Ninet ◽  
Fabrice Morganti ◽  
Jean-Philippe Lecointe ◽  
Farid Zidat ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Magnetic Circuit ◽  
Supply Voltage ◽  
Induction Machines ◽  
Tangential Component ◽  
Content Type ◽  
Internal Fault ◽  
Torque Estimation ◽  
Numerical Finite Element

Purpose This paper aims to study the influence of supply voltage variations on the external magnetic field emitted by grid-powered induction machines (IMs). Design/methodology/approach Two models are developed in the paper to analyse, for different supply voltage values, the influence of the variations of the magnetizing voltage for which there is a link with the tangential component of the external flux. The first is an analytical model based on the IM single-phase-equivalent circuit with variable magnetizing reactance to take into account the saturation of the magnetic circuit. The second is a numerical finite element simulation to model the same phenomenon. Results of both models are analysed with experimental measures of the external flux. Findings The study shows that the amplitude of the external field strongly depends on supply voltage values. Research limitations/implications The investigation is mainly focused on the tangential component of the external magnetic field which is of high importance concerning the applicability of non-invasive methods of diagnosis, as electromagnetic torque estimation developed by the authors or internal fault determination. Originality/value The originality of the paper concerns the characterization of the external flux with the supply voltage for IMs. It is shown that the magnetic circuit radiates external flux differently with the load and with the supply voltage.

A New Differential Relay Framework for Power Transformer

2014 ◽  
Vol 492 ◽  
pp. 426-430
Author(s):  
Rachid Bouderbala ◽  
Hamid Bentarzi
Keyword(s):  
Power Transformer ◽  
Circuit Breaker ◽  
Differential Protection ◽  
Test Results ◽  
Transient Currents ◽  
Fault Currents ◽  
Internal Fault ◽  
Time Signals ◽  
Data Acquisition Card ◽  
Frame Work

A differential relay that is very sensitive relay operating even at its limits may be used for protecting a power transformer. However, this characteristic may lead to unnecessary tripping due to transient currents. In order to avoid this unnecessary tripping, estimated harmonics of these currents may be required which need great computation efforts. In this paper, a new frame work is proposed using PC interfaced with a data acquisition card AD622, which acquires real-time signals of the currents, process them numerically in the computer and outputs tripping signal to the circuit breaker. All algorithms of differential protection function and blocking techniques have been implemented using the Simulink/Matlab. To validate the present work, the performance of developed relay is tested by signals generated by Simulink/MATLAB simulator under different conditions. The test results show that this proposed scheme provides good discrimination between the transient currents and the internal fault currents.

scholarly journals New Protection Scheme for Internal Fault of Multi-Microgrid

2017 ◽  
Author(s):  
Fan Zhang ◽  
Longhua Mu ◽  
Wenming Guo
Keyword(s):  
Control Strategy ◽  
Simulation Analysis ◽  
High Sensitivity ◽  
Distribution Characteristics ◽  
Distributed Generations ◽  
Protection Scheme ◽  
Fault Currents ◽  
Internal Fault ◽  
Simulation Results ◽  
Flexible Operation

Multi-microgrid has many new characteristics, such as bi-directional power flows, flexible operation modes and variable fault currents with different control strategy of inverter interfaced distributed generations (IIDGs). All these featuring aspects pose challenges to multi-microgrid protection. In this paper, current and voltage characteristics of different feeders are analyzed when fault occurs in different positions of multi-microgrid. Based on the voltage and current distribution characteristics of the line parameters, a new protection scheme for the internal fault of multi-microgrid is proposed, which takes the change of phase difference and amplitude of measured bus admittance as the criterion. This scheme with high sensitivity and reliability, has a simple principle and is easy to be adjusted. PSCAD/EMTDC is used in simulation analysis, and simulation results have verified the correctness and effectiveness of the protection scheme.

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