A Discrimination Method Between Transformer Inrush and Fault Current Based on Chromatic Monitoring

or successful transformer differential protection employment, correct discrimination between inrush current and fault current is essential. It is one of the main focuses of research and one of the main challenges for transformer protection. In this paper, a discrimination method based on utilizing chromatic monitoring of the box dimension algorithm outcome curve for transformer differential current in time-domain analysis is proposed. The x-L chromatic mapping is employed for general detection of fault cases, while the x-y chromatic mapping result is used for distinguishing inrush current from the fault current cycles. The preliminary results show that the proposed method can effectively provide correct discrimination of the current type within quite a short time and thus help in providing efficient decision-making supportive protection tool.

Setting Relai Differensial Pada Transformator Daya 150kv Gardu Induk Pondok Indah Menggunakan Protocol Communications Modbus

Transformers in power systems require different types of protection.This protection is provided by various types of relays, bothelectromagnetic and static. In general, transformer protection servesto protect the transformer in the event of a disturbance, so that thetransformer can be avoided from damage. The relay that will be usedto protect the transformer is a differential relay. This relay workswhen there is a difference in the current of the Current Transformer[CT] on the primary and secondary sides. If the fault occurs outsidethe protection zone, the relay will not work. The method used in thisresearch is R&D (Research and Development), namely research anddevelopment methods, research and development methods areresearch methods used to produce certain products, and test theeffectiveness of these products. An evaluation of the differentialrelay setting on a 150kV power transformer has been carried out atthe Pondok Indah Substation using the Modbus CommunicationsProtocol, where the settings in the field and from the results ofcalculations using the Micom 632 differential relay are obtained: forthe calculation results of Idiff = 0.39 and Idiff max = 8.07 while theactual setting in the field is Idiff = 0.3 and Idiff max = 8. Thedifference in value between the actual setting and the calculationresults is Idiff by 30%, and Idiff max 0.87% is still within theallowed interval . Setting using the modbus communicationsprotocol has advantages, including reducing wiring, makingtroubleshooting or interference easier, reducing the possibility ofhuman-error errors in the configuration process, and making it easyto make changes.

Design of Hardware Setup Based on IEC 61850 Communication Protocol for Detection & Blocking of Harmonics in Power Transformer

In this paper, the authors have developed a hardware model for blocking even and odd harmonics of a power transformer. In the proposed hardware model, intelligent differential & over-current relays are used for the blocking of harmonics of a power transformer. The harmonic restraint function on the differential relay (7UT61) prevents the relay from tripping during transformer magnetizing inrush current. However, the over-current relays which are used for back up protection does not have a harmonic restraint element, and over-current relay trips due to magnetizing inrush current, causes unwanted interruptions and power failures. The establishment of harmonic blocking scheme for over-current protection in power transformers is an important finding of this research study. IEC61850 standard-Based GOOSE (Generic Object Oriented Substation Event) applications used in power transformer protection for fast detecting and clearing of faults is an interested study presented in the proposed work.

Data analytics for cybersecurity enhancement of transformer protection

Electric power substations are experiencing an accelerated pace of digital transformation including the deployment of LAN-based IEC 61850 communication protocols that facilitate accessibility to substation data while also increasing remote access points and exposure to complex cyberattacks. In this environment, machine learning algorithms will play a vital role in cyberattack detection and mitigation and natural questions arise as to the most effective models in the context of smart grid substations. This paper compares the performance of three autoencoder-based anomaly detection systems including linear, fully connected, and convolutional autoencoders, as well as long short-term memory (LSTM) neural network for cybersecurity enhancement of transformer protection. The simulation results indicated that the LSTM model outperforms the other models for detecting cyberattacks targeting asymmetrical fault data. The linear autoencoder, fully connected autoencoder and 1D CNN further outperform the LSTM model for detecting cyberattacks targeting the symmetrical fault data.

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

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.

An electric power system object model creating experience for researching the operation of digital means of relay protection and automation

The article is devoted to the operation logic modeling of relay protection and automation terminals in order to their verification, adjustment and further exploitation. The problem of adjusting protection terminals mutual interaction is unlikely to appear in real conditions due to wide variety of them. The authors propose a solution to this problem by creating a verified model based on a digital twin of an electric power network section created in the MatLab software package. This model helps to study the functioning of the researched protection settings in nominal, repair, emergency and post-emergency equipment operation modes. A model of the selected substation was created displaying all the properties that are significant for research of the original one. In addition, the requirements analysis for the main and backup protection operation settings of the three-winding transformers was carried out. The main unit is a differential transformer relay protection and the backup one is maximal current protection in amount of three units for every transformer winding circuit: higher, middle and lower transformer voltage branch. The model makes it possible to analyze the relay protection operation selectivity by checking the current settings which could be imported from XML documents unloaded from existing terminals and to evaluate the correctness of new calculated ones with the possibility of their manual input. As a result of the researched object modeling, a three-stage operation analysis of the differential and maximal current protections was carried out. It has shown relay protection selective operation both in the case of nominal and abnormal modes, including the event of the main transformer protection malfunction. This technique can be extended to the other electric power network.

Condition Monitoring of High Voltage Transformer using Dissolved Gas Analysis Methods

Power transformer plays a significant role in the entire power transmission network; thus, transformer protection requires more attention for fault free electric supply. when the mineral oil and insulation inside the transformer is subjected to high thermal and electrical stresses, gases are created by the decay of mineral oil and cellulose. Different gases create different faults, Identification of faults inside the power transformer before they occur reduces its failure rate during its service period. For Knowing the fault condition of power transformer, Dissolved Gas Analysis (DGA) is proven to be as accurate method based on combination of concentration of gases like CO, CO2, H2, C2H6, C2H4, C2H2 etc., Dissolved gas analysis is the most important test in determining the fault condition of a transformer and it is the first indicator of a problem and can identify deteriorating insulation and oil, overheating hot spots, partial discharge and arcing. For developing this DGA Techniques, the MATLAB GUIDE interface can be used for making easy interaction between the user and software developed. This software is designed using some conditional statements and logical functions to get the type of faults in transformers based on the concentration of gases in transformer oil. The faults in transformer using dissolved gases analysis are detected using methods such as key gas, Roger’s methods, IEC ratio, Doernenburg ratio, Duval triangle and the Combined DGA methods. In this paper, these four methods of dissolved gas analysis (DGA) are presented and explained briefly.

An improved technique for power transformer protection using fuzzy logic protective relaying

The three-phase power transformer in the transmission or distribution substations represents one of the essential devices on electric power networks. Losing this devise cause a disconnection of the power utility to a large number of electrical loads. The robust protection system must be designed to protect the device during abnormal operations. A complete protection system for a poly-phase power transformer for one of the Karbala transmission networks (East Karbala substation) is modeled and simulated, adopting a fuzzy logic protective relaying using MATLAB/SIMULINK environment. This study discusses fuzzy logic-based relaying for a power transformer safety, as well as internal faults that are clearly identified. Two principles of operation are used to protect the transformer; differential relay and overcurrent relay. The differential relay is proposed as the unit protection, while the overcurrent is backup protection. The proposed fuzzy logic controller (FLC) is used to detect abnormal operation; it is also modeled to organize the operation between unit and backup protection. The numerical results clarify that the proposed model can perform fast, rigorous, and authoritative protection for the transformer. Also, modeling of the protection mode decreases the complexity of designing various subsystem and combining them in one controller.