scholarly journals Differential Protection of Power Transformer using Wavelet Transform

2019 ◽  
Vol 8 (3) ◽  
pp. 7627-7630
Keyword(s):  
Wavelet Transform ◽  
Power Transformer ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Differential Protection ◽  
Time Duration ◽  
Transform Method ◽  
Protection Scheme ◽  
Magnetizing Inrush Current ◽  
Clearing Time

This paper presents wavelet transform method for the analysis of differential currents of power transformer which can act as an accurate classifier between magnetizing inrush current and internal faults to avoid the needless tripping of circuit breaker. The differential protection scheme occasionally mal – operate whenever magnetizing inrush occurs in power transformer. The aim is to reduce the rate and time duration of undesired outages of power transformer. This includes the necessities of reliability with zero mal – operation of differential relay. The result shows higher operating speed with less fault clearing time. Wavelet Transform is employed for the analysis of transient signals under various conditions, which extracts data from signals in time and frequency domain simultaneously. The simulation is done in MATLAB environment.

scholarly journals Adaptive ANN based differential protective relay for reliable power transformer protection operation during energisation

2019 ◽  
Vol 8 (4) ◽  
pp. 307
Author(s):  
Azniza Ahmad ◽  
Mohammad Lufti Othman ◽  
Kurreemun Khudsiya Bibi Zainab ◽  
Hashim Hizam
Keyword(s):  
Power Transformer ◽  
Electrical Power ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Electrical Power System ◽  
Transformer Protection ◽  
Protection Scheme ◽  
Internal Fault ◽  
Magnetizing Inrush Current ◽  
Harmonic Restraint

Power transformer is the most expensive equipment in electrical power system that needs continuous monitoring and fast protection response. Differential relay is usually used in power transformer protection scheme. This protection compares the difference of currents between transformer primary and secondary sides, with which a tripping signal to the circuit breaker is asserted. However, when power transformers are energized, the magnetizing inrush current is present and due to its high magnitude, the relay mal-operates. To prevent mal-operation, methods revolving around the fact that the relay should be able to discriminate between the magnetizing inrush current and the fault current must be studied. This paper presents an Artificial Neural Network(ANN) based differential relay that is designed to enable the differential relay to correct its mal-operation during energization by training the ANN and testing it with harmonic current as the restraining element. The MATLAB software is used to implement and evaluate the proposed differential relay. It is shown that the ANN based differential relay is indeed an adaptive relay when it is appropriately trained using the Network Fitting Tool. The improved differential relay models also include a reset part which enables automatic reset of the relays. Using the techniques of 2nd harmonic restraint and ANN to design a differential relay thus illustrates that the latter can successfully differentiate between magnetizing inrush and internal fault currents. With the new adaptive ANN-based differential relay, there is no mal-operation of the relay during energization. The ANN based differential relay shows better performance in terms of its ability to differentiate fault against energization current. Amazingly, the response time, when there is an internal fault, is 1 ms compared to 4.5 ms of the conventional 2nd harmonic restraint based relay.

A New Algorithm for Three-Phase Power Transformer Differential Protection Considering Effect of Ultra-Saturation Phenomenon Based on Discrete Wavelet Transform

2018 ◽  
Vol 20 (1) ◽  
Author(s):  
Bahram Noshad
Keyword(s):  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Power Transformer ◽  
Discrete Wavelet ◽  
Inrush Current ◽  
Differential Protection ◽  
Inductive Load ◽  
Saturation Phenomenon ◽  
Three Phase ◽  
Transformer Differential Protection

Abstract One of transient phenomena that lead to the false trip of the power transformer differential protection during the energization of a loaded power transformer is the ultra-saturation phenomenon. This paper presents, at first, a new algorithm for three-phase power transformer differential protection considering effect of the ultra-saturation phenomenon based on Discrete Wavelet Transform (DWT). To model the ultra-saturation phenomenon, the nonlinear characteristic of the transformer core and the effect of the saturation of the current transformers are taken into account. It is assumed that the load of the transformer is a resistive and inductive load. In this algorithm, the ultra-saturation phenomenon, the external and internal faults of power transformer and the magnetic inrush current are simulated. To distinguish between these phenomena, appropriate criteria using DWT by the use of standard deviation of coefficients are presented. Also, one of the most important criteria for the digital relays is the time for making a decision. Thus, to determine the time of decision, the experimental results will be presented.

Research on the Influence of Closing Resistor inside Circuit Breaker on Magnetizing Inrush Current of UHV Transformer

2014 ◽  
Vol 986-987 ◽  
pp. 2001-2005
Author(s):  
Zhen Guo ◽  
Hui Yuan Zhang ◽  
Bo Wang ◽  
Ren Min Gong ◽  
Yong Hao Zhang
Keyword(s):  
Simulation Model ◽  
Simulation Analysis ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Differential Protection ◽  
Matlab Simulink ◽  
Magnetizing Inrush Current ◽  
The Impact

Using Matlab/Simulink software established the simulation model of UHV transformer and UHV power grid.The characteristic of magnetizing inrush current for UHV transformer was obtained by simulation.The paper also analyzed the impact on differential protection from it. Closing resistor inside circuit breaker method was proposed to restrain magnetizing inrush current.The method cuts down the amplitude and accelerated the attenuation speed of it, so as to restrain it. The simulation analysis verified the effectiveness of the method.

Evaluation of the Power Transformer Magnetizing Inrush Currents

2020 ◽  
Vol 10 (10) ◽  
pp. 20-32
Author(s):  
Aleksey A. KUVSHINOV ◽  
◽  
Vera V. VAKHNINA ◽  
Aleksey N. CHERNENKO ◽  
◽  
...  
Keyword(s):  
Power Transformer ◽  
Geomagnetic Disturbance ◽  
Inrush Current ◽  
Geomagnetic Disturbances ◽  
Disturbance Intensity ◽  
Magnetizing Inrush Current ◽  
Inrush Currents ◽  
Instantaneous Values ◽  
The Mathematical Model ◽  
Analytical Expressions

The mathematical model of a shell-core power transformer’s magnetization branch is substantiated. By using the model, analytical expressions for the magnetizing current instantaneous values under the conditions of geomagnetic disturbances can be obtained. Quantitative assessments of the magnetizing inrush current amplitudes and durations versus the geomagnetic disturbance intensity are obtained. The dynamics of the power transformer magnetic system saturation transient and changes in the magnetization inrush current amplitudes and durations after a sudden occurrence of geomagnetic disturbances are shown. The error of estimating the magnetizing inrush current amplitudes under geomagnetic disturbances is determined based on comparison with experimental data.

A power transformer differential protection based onsupport vector machine and wavelet transform

2021 ◽  
Vol 197 ◽  
pp. 107297
Author(s):  
Lucas D. Simões ◽  
Hagi J.D. Costa ◽  
Matheus N.O. Aires ◽  
Rodrigo P. Medeiros ◽  
Flavio B. Costa ◽  
...  
Keyword(s):  
Wavelet Transform ◽  
Power Transformer ◽  
Differential Protection ◽  
Transformer Differential Protection

The Feasible Analysis of Transformer Fast Reenergizing with Neutral Point Ungrounded

2013 ◽  
Vol 732-733 ◽  
pp. 958-964
Author(s):  
Yao Zhao ◽  
Yu De Yang ◽  
Yan Hong Pan ◽  
Le Qi
Keyword(s):  
High Voltage ◽  
Power Supply ◽  
Low Voltage ◽  
Second Harmonic ◽  
Neutral Point ◽  
Inrush Current ◽  
Differential Protection ◽  
Time Saving ◽  
Magnetizing Inrush Current ◽  
Transformer Differential Protection

The feasibility of transformer fast reenergizing with neutral point ungrounded after the external fault being removed is analyzed in this paper. By calculating overvoltage and discriminating magnetizing inrush current, it analyzes four ways to restore power of transformer and chooses the optimal strategy which is safe and time-saving. The result shows that in the case of transformer neutral point ungrounded, closing the low-voltage circuit side breaker before the high-voltage, which can effectively limit over-voltage in a safe range. The second harmonic characteristic of magnetizing waveform may disappear, while the intermittent angle characteristics are still significant. With the help of the intermittent angle principle, transformer differential protection may not misuse. The average time for each customer interruption is reduced from 40 minutes to 10 minutes and saves an hour for engineer on the way back and forth. It will greatly improve power supply reliability.

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