A Study on Transmission Line Backup Protection based on Differential Algorithm Using IEC-61850 Asynchronous Positive Sequence Voltages and Negative Sequence Currents

The paper discusses the effects of the presence of subharmonics (i.e. frequencies lower than the basic 50 Hz) in the voltage supplying the induction machine. Subharmonics in a three-phase grid are the result of the oscillations of peak values of the voltages. In induction machines, this results in the subharmonic and interharmonic currents, the generation of alternating moments, the increase in the rms value of the current of the fundamental harmonic and the oscillations of the rotor speed. In the paper is derived expression on the thermally acceptable load of the motor (by torque and power), in the case of supplying it by three-phase voltage containing a positive sequence of subharmonics. It presented the obstacles to derive the analogical expression for power supply containing a negative sequence of subharmonics.

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Operation of an induction motor supplied by voltage with interharmonics

Science Technology and Innovation ◽

10.5604/01.3001.0012.1305 ◽

2018 ◽

Vol 2 (1) ◽

pp. 47-53 ◽

Cited By ~ 1

Author(s):

Tomasz Drabek

Keyword(s):

Induction Motor ◽

Fundamental Frequency ◽

Skin Effect ◽

Induction Machines ◽

Positive Sequence ◽

Rotor Speed ◽

Negative Sequence ◽

Three Phase ◽

Total Multiplicity ◽

Rotor Cage

The paper discusses the effects of interharmonics, i.e. frequencies higher than the fundamental frequency, not being its total multiplicity, in the voltage supplying the induction motor. The emergence of interharmonics in a three-phase grid is mainly the result of the swinging of peak mains voltages. In induction machines, this results in the occurrence of currents with interharmonic and subharmonic frequencies, the generation of alternating moments, the swinging of the rotor speed and the change in the RMS value of the current of the fundamental frequency. The paper explores these phenomena simulation, taking into account the skin effect of currents in the rotor cage. The research was carried out both for interharmonics with a positive sequence of phases as well as for the negative sequence. The paper is a continuation of work [1].

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Detection and Identification of Error in On-Line Monitoring of Transmission Line

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.687-691.869 ◽

2014 ◽

Vol 687-691 ◽

pp. 869-873

Author(s):

Song Hai Fan ◽

Shu Hong Yang

Keyword(s):

Wavelet Analysis ◽

Transmission Line ◽

Systematic Approach ◽

Abrupt Change ◽

Power Grid ◽

Positive Sequence ◽

Test Results ◽

Detection And Identification ◽

On Line ◽

Sequence Parameters

Systematic approach for the transmission line positive sequence parameters, temperature, and sag based on wavelet analysis to detect error is developed in this work. Unbiased (random/Gaussian) error such as, transient meter failures, transient meter malfunction, and measurements captured during system transients, are inherently in the form of large abrupt change of short duration in a measurement-sequence. These should be detected before the data is used because their presence will lead to insecure and unstable of power grid. The test results of the proposed method based on data of Sichuan power grid are presented.

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Iterative Fault Location Scheme for a Transmission Line Using Synchronized Phasor Measurements

International Journal of Emerging Electric Power Systems ◽

10.2202/1553-779x.1733 ◽

2007 ◽

Vol 8 (6) ◽

Cited By ~ 4

Author(s):

Sukumar M Brahma

Keyword(s):

Transmission Line ◽

Fault Location ◽

Positive Sequence ◽

Impedance Matrix ◽

Fault Resistance ◽

Distributed Parameters ◽

Phasor Measurements ◽

Sequence Components ◽

Simulation Results ◽

New Iterative Method

This paper describes a new iterative method to locate fault on a single transmission line. The method uses synchronized voltage and current measurements from both line terminals. Using the positive sequence components of the pre-fault and the post-fault phasors, positive sequence source impedances at both terminals are first estimated. Using these source impedances and the line data, the positive sequence bus impedance matrix (Zbus) is formed. Using the properties of Zbus, an iterative algorithm is proposed to locate the fault. This algorithm is tested extensively with data obtained from the EMTP simulation of a long transmission line simulated with distributed parameters in the presence of fault resistance and CT saturation. The simulation results show that the method is very accurate and robust.

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