scholarly journals Discrimination of Transformer Inrush Currents and Internal Fault Currents Using Extended Kalman Filter Algorithm (EKF)

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6020
Author(s):  
Sunil Kumar Gunda ◽  
Venkata Samba Sesha Siva Sarma Dhanikonda
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Threshold Level ◽  
Transformer Protection ◽  
Protection Scheme ◽  
Fault Currents ◽  
Internal Fault ◽  
Absolute Residual ◽  
Inrush Currents ◽  
Internal Faults

The discrimination of inrush currents and internal fault currents in transformers is an important feature of a transformer protection scheme. The harmonic current restrained feature is used in conventional differential relay protection of transformers. A literature survey shows that the discrimination between the inrush currents and internal fault currents is still an area that is open to research. In this paper, the classification of internal fault currents and magnetic inrush currents in the transformer is performed by using an extended Kalman filter (EKF) algorithm. When a transformer is energized under normal conditions, the EKF estimates the primary side winding current and, hence, the absolute residual signal (ARS) value is zero. The ARS value will not be equal to zero for internal fault and inrush phenomena conditions; hence, the EKF algorithm will be used for discriminating the internal faults and inrush faults by keeping the threshold level to the ARS value. The simulation results are compared with the theoretical analysis under various conditions. It is also observed that the detection time of internal faults decreases with the severity of the fault. The results of various test cases using the EKF algorithm are presented. This scheme provides fast protection of the transformer for severe faults.

A suggested differential protection scheme for power transformer

2014 ◽  
Vol 5 (2) ◽  
pp. 91-103 ◽  
Author(s):  
E. Ahmed ◽  
R. El-Sehiemy
Keyword(s):  
High Speed ◽  
Power Transformer ◽  
Normal Operation ◽  
Power Differential ◽  
Transformer Protection ◽  
Protection Scheme ◽  
Wide Range ◽  
Inrush Currents ◽  
Differential Scheme ◽  
External Faults

This paper integrates a Real Power Differential Scheme (RPDS) for power transformer protection. The suggested RPDS for power transformer computes the active power loci during normal operation, switching, normal, and internal, involves turn to turn, and external faults at varied load angles. The proposed RPDS concept is based on monitoring and comparing the transformers primary and secondary active and reactive powers. The dynamic response of the proposed RPDS is tested 300 MVA, 220/66 kV, Y/Δ transformer. Furthermore, the suggested scheme is simulated with the use of Matlab/Simulink then tested for various fault and switching conditions. Moreover, the RPDS is checked for inter turn fault conditions at primary and secondary sides. The evaluation of the suggested scheme confirms the superiority of the proposed scheme to distinguish internal and external faults as well as magnetizing inrush currents with good selectivity, high speed, sensitivity, stability limits and high accuracy response of the power differential scheme. Finally, the suggested scheme is able to detect correctly the turn to turn faults for wide range of fault resistances but fails at very low values.

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.

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.

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