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 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 The study of power transformer differential protection’s operation in the internal fault conditions

2021 ◽  
Vol 288 ◽  
pp. 01096
Author(s):  
Ilya Litvinov ◽  
Aleksandra Naumova ◽  
Vasiliy Titov ◽  
Andrey Trofimov ◽  
Elena Gracheva
Keyword(s):  
Power System ◽  
High Speed ◽  
Power Transformer ◽  
Short Circuit ◽  
Differential Protection ◽  
Current Transformers ◽  
Secondary Currents ◽  
A Value ◽  
Internal Fault ◽  
Internal Short Circuit

Special attention is paid to high-speed relay protections’ operation in transient modes due to a number of major failure events that have occurred over the past 10 years in the power system of the Russian Federation. Operation of power transformer’s differential protection in case of internal short circuit is studied in this research. False blocking of protection is possible in such mode due to saturation of current transformers. A value of blocking time may exceed the maximum permissible short-circuit disconnection time under conditions of maintaining the dynamic stability of the power system. Primary and secondary currents in transient modes are obtained by simulation of short circuits. Windings of the modeled current transformers are connected in a star to a null wire. RMS values are calculated using a mathematical model of the Fourier filter. The current transformers were checked according to the methods declared in PNST 283-2018 and GOST R 58669-2019. The analysis carried out in this work allows to estimate possibility of long-term blocking of the differential protection of a power transformer in case of internal short circuit, especially in case of significant value of time constants.

scholarly journals Design and Evaluation of a DSP Based Differential Relay of Power Transformer

2021 ◽  
Vol 1 (1) ◽  
pp. 69-78
Author(s):  
Abdelkader ABDELMOUMENE ◽  
Rachid BOUDERBALA ◽  
Hamid BENTARZI
Keyword(s):  
Harmonic Analysis ◽  
Power Transformer ◽  
Inrush Current ◽  
Differential Protection ◽  
Challenging Problem ◽  
Good Discrimination ◽  
Internal Fault ◽  
Magnetizing Current

The problem of mal operation of differential protection of power transformer due to the inrush magnetizing current has long considered as a challenging problem. Several types of protection relays have been used to solve the issue (basic relay, percentage relay, multi slop ….). Each of them has its advantage and its limits. In this paper, a Digital differential relay has been developed and simulated. The logic used to distinguish between the inrush current and the internal fault is based on the theory of harmonic analysis. The behavior of the presented relay has been simulated versus various situations (inrush current, internal fault and external fault). The obtained results show that the proposed algorithm provides a good discrimination and a fast action.

Differential Protection Enhancement for Power Transformer

2021 ◽  
pp. 322-346
Author(s):  
Hamid Bentarzi ◽  
Rachid Bouderballa
Keyword(s):  
Power Transformer ◽  
Second Harmonic ◽  
Inrush Current ◽  
Differential Protection ◽  
Smart Power ◽  
The Third ◽  
Internal Fault ◽  
Harmonic Components ◽  
Magnetization Condition ◽  
Advanced Computer

A power transformer is protected against internal faults using a differential protection which is sensitive and a fast. However, during transformer magnetization (inrush current or over-excitation), the differential relay may operate unnecessarily. This phenomenon appears only when a transformer is first energized or after clearing external fault. During periodic magnetization condition due to over-excitation, the third and fifth harmonic components are largely noticed; however, during the normal apperiodic inrush conditions, the second harmonic is relatively high. In the conventional techniques, these harmonic components have been used to block differential protection to operate. However, in smart power transformer, these harmonic components are small even during the transformer magnetization; they cannot be used as block protection functions. The differential protection security has to be improved so that it can distinguish between differential current produced by magnetization and that produced by internal fault using the most advanced computer with most improved DSP algorithms.

scholarly journals Impact of Momentary Cessation Voltage Level in Inverter-Based Resources on Increasing the Short Circuit Current

2019 ◽  
Vol 11 (4) ◽  
pp. 1153 ◽  
Author(s):  
Namki Choi ◽  
Bohyun Park ◽  
Hwanhee Cho ◽  
Byongjun Lee
Keyword(s):  
Power Systems ◽  
Short Circuit ◽  
Circuit Breaker ◽  
Short Circuit Current ◽  
Fault Current ◽  
Test Results ◽  
Voltage Level ◽  
Fault Currents ◽  
Current Calculation ◽  
The Impact

This study analyzed the impact of varying the momentary cessation (MC) voltage level on the short circuit current of inverter-based resources (IBRs). To analyze the impact of the IBR MC function on the short circuit current, this paper proposes an advanced IBR model for fault current calculation to reflect its fault characteristics and a scheme for analyzing the influence of MC on the short circuit current. Based on the proposed methods, the authors conducted case studies using planning data from the Korea Electric Power Corporation (KEPCO). The influence of MC was investigated on the IBRs located at the southwest side of the KEPCO systems by screening the fault currents while varying the MC voltage. This paper demonstrates that the minimum MC voltage level needed for the fault current not to exceed the circuit breaker (CB) capacity can be proposed through analyzing the impact of MC voltage level on the short circuit current. The test results based on the proposed scheme showed that the short circuit current to power systems could not violate CB capacity if IBRs adjusted the MC voltage level higher than the lowest MC voltage level.

scholarly journals Identification of Power Transformer Currents by Using Random Forest and Boosting Techniques

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Tamer Khatib ◽  
Gazi Arar
Keyword(s):  
Expert System ◽  
Random Forest ◽  
Power Transformer ◽  
Confusion Matrix ◽  
The Other ◽  
Differential Protection ◽  
Learning Machines ◽  
Internal Fault ◽  
Component Importance ◽  
Importance Analysis

In this research, a differential protection technique for a power transformer is proposed by using random forest and boosting learning machines. The proposed learning machines aim to provide a protection expert system that distinguishes between different transformer status which are normal, inrush, overexcitation, CT saturation, or internal fault. Data for 20 different transformers with 5 operating cases are used in this research. The utilized random forest and boosting techniques are trained using these data. Meanwhile, the proposed models are validated by other measures such as out-of-bag error and confusion matrix. In addition, variable importance analysis that shows signal’s component importance inside a transformer at different instances is provided. According to the result, the proposed random forest model successfully identifies all of the current cases (100% accuracy for the conducted experiment). Meanwhile, it is found that it is less accurate as a conditional monitoring element with accuracy in the range of 97%–98%. On the other hand, the proposed boosting model identifies all of the currents for both cases (100% accuracy for the conducted experiment). In addition to that, a comparison is conducted between the proposed models and other AI-based models. Based on this comparison, the proposed boosting model is the simplest and the most accurate model as compared to other models.

Simulation of Transformer Protection Based on an Embedded MATLAB Function

2014 ◽  
Vol 960-961 ◽  
pp. 995-999
Author(s):  
Wei Cai ◽  
Lin Sun ◽  
Hua Ren Wu
Keyword(s):  
Simulation Model ◽  
Second Harmonic ◽  
Circuit Breaker ◽  
Inrush Current ◽  
Differential Protection ◽  
Transformer Protection ◽  
Function Block ◽  
Internal Fault ◽  
Harmonic Restraint ◽  
Transformer Differential Protection

This paper establishes a simulation model of a simplified power system with transformer differential protection based on an embedded Matlab function block. The differential protection consists of percentage restraint differential protection, second harmonic restraint, differential current instantaneous trip protection and over-excitation protection. The model is able to correctly simulate the transformer’s inrush current and internal and external faults. The results from the simulation show that the circuit breaker correctly operates for a transformer internal fault and provides a good braking effect for an external fault. In addition, the protection model is able to identify the inrush current of the transformer and avoid a protection mis-trip event.

Sign in / Sign up

Export Citation Format

Share Document