Enhancing Power Transformer Differential Protection to Improve Security and Dependability

Sevov, Lubomir; Khan, Umar; Zhang, Zhiying

doi:10.1109/tia.2017.2670525

Cited by 18 publications

(8 citation statements)

References 2 publications

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“…HV MCT Ratio or LV MCT Ratio = a = I sec ondary I primary (7) Referring to Figure 6a and using HV MCT Ratio, we can illustrate that upon the injection of balanced three phase nominal HV secondary current (0.35A) into corresponding relay current elements with no current injection into LV side relay current elements, current equal to 1A flows in secondary of HV MCT, resulting in flow of I di f f = 1 pu using Equation (5) and I bias = 0.5 pu using Equation (6). In Figure 6a, the phase shift of three phases is shown through clock convention, where 0 corresponds to 0 • , 4 corresponds to −120 • , and 8 corresponds to −240 • .…”

Section: Measurement Testmentioning

confidence: 99%

“…The authors have used a software-based simulator that utilizes iterations for the determination of settings. Furthermore, enhancement techniques for power transformer differential protection are described in [7], in which the author also discussed internal and external fault cases for differential protection and conducted a simulation testing through real-time digital simulation.…”

Section: Introductionmentioning

confidence: 99%

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A Detailed Testing Procedure of Numerical Differential Protection Relay for EHV Auto Transformer

et al. 2021

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In power systems, the programmable numerical differential relays are widely used for the protection of generators, bus bars, transformers, shunt reactors, and transmission lines. Retrofitting of relays is the need of the hour because lack of proper testing techniques and misunderstanding of vital procedures may result in under performance of the overall protection system. Lack of relay’s proper testing provokes an unpredictability in its behavior, that may prompt tripping of a healthy power system. Therefore, the main contribution of the paper is to prepare a step-by-step comprehensive procedural guideline for practical implementation of relay testing procedures and a detailed insight analysis of relay’s settings for the protection of an Extra High Voltage (EHV) auto transformer. The experimental results are scrutinized to document a detailed theoretical and technical analysis. Moreover, the paper also covers shortcomings of existing literature by documenting specialized literature that covers all aspects of protection relays, i.e., from basics of electromechanical domain to the technicalities of the numerical differential relay covering its detailed testing from different reputed manufacturers. A secondary injection relay test set is used for detailed testing of differential relay under test, and the S1 Agile software is used for protection relay settings, configuration modification, and detailed analysis.

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Section: Measurement Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A Detailed Testing Procedure of Numerical Differential Protection Relay for EHV Auto Transformer

et al. 2021

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“…The leakage flux fault detection strategies are classified into the vibration-based method (VBM) and search coil-based method (SCBM), and flux leakage-based methods; they were studied and compared. This modelling aims to achieve an FRA -The capacitive effect can be detected at high frequency -This method needs previous data on the transformer -This method needs complicated tools for detection -Offline method -Needs expert's opinion and sophisticated instruments [12,[16][17][18] Negative sequence -The signal for fault detection is available -Unable to locate the fault [19,20] Partial discharge -Well-established method in power utilities -This method is under the influence of tank and windings [21][22][23] Flux-based method -Precise and accurate -Exact fault location detection -Changes in the transformer structure -Models developed for verification purposes -Requires the details of the transformer structure and sensors [7,8,11,24] Voltage and current measurement -Models developed for verification purpose -Unable to locate the fault [9,25,26] Differential protection -Classical robust method -Online monitoring is possible -Unable to detect inter-turn faults at initial levels -Mainly depends on the precision of the current transformer -Sensitive to winding insulations breakdown -Sensitive to the structure of the transformer [27][28][29] Intelligent approach -Detect minute faults -Robust against missing data…”

Section: Introductionmentioning

confidence: 99%

Transformer inter‐turn failure detection based on leakage flux and vibration analysis

Hajiaghasi

Ahmadi

Goleij

et al. 2021

IET Electric Power Appl

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Inter‐turn winding fault is one of the most critical failures of the transformers. Here, a comprehensive transformer leakage flux analysis under inter‐turn winding fault is presented, and the feasibility and sensitivity of leakage flux‐based fault detection methods are investigated. The leakage flux fault detection strategies are classified into vibration‐based methods and search coil‐based methods. Flux leakage‐based methods have been studied and compared. Moreover, the effects of various important factors, such as fault severity, fault location, load power factor, and loading rate in transformer under inter‐turn faults are studied. Furthermore, two new online methods based on leakage flux and vibration analysis are proposed. In the first method, search coils voltage analysis is used for fault detection. In the second one, the vibration of the transformer is measured using the Digital Accelerometer (ADXL) sensor and compared with the vibration of the normal conditions, and based on the amount of vibration, fault detection is performed. The simulation and experimentation results on 20/0.4 kV, 50 kVA distribution transformer demonstrated that the implementation of leakage flux‐based methods provides valuable information on the transformer behaviour, which can be used to detect transformer winding faults.

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“…The differential protection is enhanced in [29], with a classical and robust detection method. The approach however, is unable to detect interterm fault at inception level.…”

Section: Introductionmentioning

confidence: 99%

A New Practical Approach for Discrimination between Inrush Currents and Internal Faults in Power Transformers

Mohammadpour

Dashti

Shaker

2020

Technol Econ Smart Grids Sustain Energy

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The power transformers are protected by differential relays. These relays use the second harmonic blocking to distinguish inrush current from internal fault current. In recent years, the performance of the second harmonic blocking has decreased and therefore new methods are needed to distinguish inrush current from internal fault current. The aim of this study is to present a new method for discrimination between magnetizing inrush currents and internal faults in differential protection of power transformers. The proposed scheme is based on calculating the dq0 transformation of current signals in the abc phases of transformer terminals for different inrush current and internal fault signals. Creating new waveforms using mathematical calculations, the signals are identifiable by their characteristics. The accurate diagnosis is based on creating a classification pattern for the discrimination algorithm. To substantiate the preciseness of proposed methodology, different states of inrush and fault currents are simulated in PSCADTM/EMTDCTM. Consequently, calculations and the distinction process are carried-out in MATLAB environment. The discrimination procedure needs only current signal data of less than a quarter of power frequency cycle and uses very simple classification rules. Eventually, both simulation and experimental results show that the accuracy of proposed method is high. The results of this study confirm that simple and accurate methods which use patterns can be developed for distinguishing the internal faulty current of transformer from inrush and healthy current.

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Enhancing Power Transformer Differential Protection to Improve Security and Dependability

Cited by 18 publications

References 2 publications

A Detailed Testing Procedure of Numerical Differential Protection Relay for EHV Auto Transformer

A Detailed Testing Procedure of Numerical Differential Protection Relay for EHV Auto Transformer

Transformer inter‐turn failure detection based on leakage flux and vibration analysis

A New Practical Approach for Discrimination between Inrush Currents and Internal Faults in Power Transformers

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