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1
Litvinov, Ilya, Aleksandra Naumova, Vasiliy Titov, Andrey Trofimov, and Elena Gracheva. "The study of power transformer differential protection’s operation in the internal fault conditions." E3S Web of Conferences 288 (2021): 01096. http://dx.doi.org/10.1051/e3sconf/202128801096.
Full textAbstract:
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.
2
Kolesov, L. M., and V. V. Mozhzhukhina. "Distance backup protection using supply currents on a line with several branches." Vestnik IGEU, no. 6 (2019): 49–59. http://dx.doi.org/10.17588/2072-2672.2019.6.049-059.
Full textAbstract:
The third step of distance protection is used as backup protection against phase-to-phase short circuits on 110–220 kV transmission lines. The main problem when using these protections on a line with several branches is to ensure the effectiveness of distant backup protection in case of phase-to-phase short circuits behind branch transformers of substations. The effective solution to distant backup protection is possible to provide by expanding the information base of protection. Currently, backup protection of lines with branches is being developed with control of currents and their components when using a communication channel, and based on algorithmic models of the facility. In this regard, the urgent task is to develop an algorithm for the distance protection ensuring the required sensibility during short circuits on the lower voltage side of the branch transformers. Analytical methods of determining the impedance measurement and simulation in Simulink and SimPowerSystems of the Matlab modeling system are used. The effectiveness of distant backup protection can be evaluated on the basis of recognition possibility of short circuit modes behind the branch transformers. Analytical expressions have been obtained to determine the impedance measurement during phase-to-phase short-circuits behind a branch transformer and under load conditions. Criteria have been developed to assess the proposed protection possibility to recognize the mode of phase-to-phase short circuits behind the branch transformer. Studies have shown that the main factor determining the possibility of mode recognition is the ratio between the protected transformer power and the total power of the branches loads. The use of several impedance measuring elements with their own response characteristics for branches with transformers of different capacities provides mode recognition for any possible correlation of power of branch substations. The use of the distance protection implementation option developed by the authors allows providing the required sensitivity for short circuits behind branch transformers and to solve the problem of distance backup line protection on a line with several branches. The reliability of the data obtained is confirmed by the correspondence of analytical research and simulation results.
3
LARIN, Vasily S., and Daniil A. MATVEEV. "Approximation of Transient Resonance Voltages and Currents in Power Transformer Windings to Determine Their Natural Frequencies and Damping Factors." Elektrichestvo 12, no. 12 (2020): 44–54. http://dx.doi.org/10.24160/0013-5380-2020-12-44-54.
Full textAbstract:
Transient interaction between power transformers and power cable lines may give rise to resonance overvoltages in the transformer primary windings. To develop protection measures against resonance overvoltages and to design transformers resistant to resonance overvoltages, it is necessary to know the natural frequencies of the transformer windings. Recent years have seen very rapid development of transformer windings high-frequency models. However, the mathematical models used in practice, which came from calculations of impulse overvoltages in transformer windings, reproduce the frequency dependences of losses and damping at natural frequencies with insufficient accuracy. To verify and improve the mathematical models used for analyzing high-frequency processes in transformer windings, it is necessary to have sufficient experimental data on the values of natural frequencies and damping factors. Methods for experimentally determining the natural frequencies and damping factors of power transformer windings are considered. Theoretical principles and analytical expressions for transient voltages and currents obtained for simplified equivalent circuits of windings with lumped parameters are given. An approach is proposed, according to which the transient voltages and currents in the winding are represented as the sum of steady-state and free components. The free component is then approximated using the theoretical expressions obtained for the equivalent circuits of the windings. The results of applying the approach to approximating the transient voltage at the midpoint and the current in the neutral of a dry-type transformer’s high-voltage winding are presented.
4
Zhang, Yong. "Study on Relay Protection Technology in Power System." Applied Mechanics and Materials 521 (February 2014): 414–17. http://dx.doi.org/10.4028/www.scientific.net/amm.521.414.
Full textAbstract:
Relay protection devices for safe and stable operation of the power system plays a vital role. In this thesis, the transformer protection principles, in-depth analysis of the various protection principles and constitutes a transformer, transformer protection built digital simulation model protection methods, and transformers of various simulation models for simulation analysis, the study showed that a new type of power system protection technology can effectively guarantee the safety performance of the power transmission system.
5
Kirui, Kemei Peter, David K. Murage, and Peter K. Kihato. "Impacts of Placement of Wind Turbine Generators on IEEE 13 Node Radial Test Feeder In-Line Transformer Fuse-Fuse Protection Coordination." European Journal of Engineering Research and Science 5, no. 6 (June 7, 2020): 665–74. http://dx.doi.org/10.24018/ejers.2020.5.6.1939.
Full textAbstract:
The ever increasing global demand on the electrical energy has lead to the integration of Distributed Generators (DGs) onto the distribution power systems networks to supplement on the deficiencies on the electrical energy generation capacities. The high penetration levels of DGs on the electrical distribution networks experienced over the past decade calls for the grid operators to periodically and critically asses the impacts brought by the DGs on the distribution network operations. The assessment on the impacts brought by the DGs on the distribution network operations is done by simulating the dynamic response of the network to major disturbances occurring on the network like the faults once the DGs have been connected into it. Connection of Wind Turbine Generators (WTGs) into a conventional electrical energy distribution network has great impacts on the short circuit current levels experienced during a fault and also on the protective devices used in protecting the distribution network equipment namely; the transformers, the overhead distribution lines, the underground cables and the line compensators and the shunt capacitors commonly used/found on the relatively long rural distribution feeders. The main factors which contribute to the impacts brought by the WTGs integration onto a conventional distribution network are: The location of interconnecting the WTG/s into the distribution feeder; The size/s of the WTG/s in terms of their electrical wattage penetrating the distribution network; And the type of the WTG interfacing technology used labeled/classified as, Type I, Type II, Type III and Type IV WTGs. Even though transformers are the simplest and the most reliable devices in an electrical power system, transformer failures can occur due to internal or external conditions that make the transformer incapable of performing its proper functions. Appropriate transformer protection should be used with the objectives of protecting the electrical power system in case of a transformer failure and also to protect the transformer itself from the power system disturbances like the faults. This paper was to investigate the effects of integrating WTGs on a distribution transformer Fuse-Fuse conventional protection coordination scheme. The radial distribution feeder studied was the IEEE 13 node radial test feeder and it was simulated using the Electrical Transient Analysis Program (ETAP) software for distribution transformer Fuse-Fuse protection coordination analysis. The IEEE 13 Node radial test feeder In-line transformer studied is a three-phase step down transformer having a star solidly grounded primary winding supplied at and a star solidly grounded secondary winding feeding power at a voltage of . The increase on the short circuit currents at the In-line transformer nodes due to the WTG integration continuously reduces the time coordination margins between the upstream fuse F633 and the downstream fuse F634 used to protect the transformer.
6
Iqteit, Nassim A., and Khalid Yahya. "Simulink model of transformer differential protection using phase angle difference based algorithm." International Journal of Power Electronics and Drive Systems (IJPEDS) 11, no. 2 (June 1, 2020): 1088. http://dx.doi.org/10.11591/ijpeds.v11.i2.pp1088-1098.
Full textAbstract:
<p class="p1">An application of phase-angle-difference based algorithm with percentage differential relays is presented in this paper. In the situation where the transformer differential relay is under magnetizing inrush current, the algorithm will be utilized to block the process. In this study, the technique is modeled and implemented using Simulink integrated with MATLAB. The real circuit model of power transformer and current transformers are considered in the simulation model. The results confirmed the effectiveness of the technique in different operation modes; such as, magnetizing inrush currents, current transformers saturation and internal transformer faults.</p>
7
Pourakbari-Kasmaei, Mahdi, Farhan Mahmood, and Matti Lehtonen. "Optimized Protection of Pole-Mounted Distribution Transformers against Direct Lightning Strikes." Energies 13, no. 17 (August 24, 2020): 4372. http://dx.doi.org/10.3390/en13174372.
Full textAbstract:
Direct lightning strikes on overhead phase conductors result in high overvoltage stress on the medium voltage (MV) terminals of pole-mounted transformers, which may cause considerable damage. Therefore, introducing an efficient protection strategy would be a remedy for alleviating such undesirable damages. This paper investigates the optimized protection of MV transformers against direct lightning strikes on the phase conductors. To this end, first, the impacts of grounding densities (number of grounded intermediate poles between every two successive transformer poles) on the probability of overvoltage stress on transformer terminals are investigated. Then, the implications of guy wire, as a supporting device for ungrounded intermediate poles, on reducing the overvoltage stress on transformers, are studied. Finally, the role of a surge arrester in mitigating the overvoltage stress of non-surge-arrester-protected transformer poles is scrutinized. The investigations are conducted on a sample MV network with 82 wood poles comprising 17 pole-mounted transformers protected by spark gaps. To provide in-depth analysis, two different poles, namely creosote- and arsenic-impregnated poles, are considered under wet and dry weather conditions. A sensitivity analysis is performed on grounding distances and on a combination of guy wire and grounded intermediate poles while taking into account soil ionization. The results provide a clear picture for the system operator in deciding how many grounded intermediate poles might be required for a system to reach the desired probabilities of transformers experiencing overvoltage stress and how the surge arrester and guy wires contribute to mitigating undesirable overvoltage stress.
8
Krutikov, Kirill K., Vyacheslav V. Rozhkov, and Vladimir V. Fedotov. "Simulation of the saturation process of a current transformer with a load." Journal Of Applied Informatics 16, no. 4 (August 31, 2021): 48–61. http://dx.doi.org/10.37791/2687-0649-2021-16-4-48-61.
Full textAbstract:
The article deals with the mathematical basis and simulation of the saturation processes of current transformers with aperiodic components of short-circuit currents. Saturation processes of current transformers can affect the correct operation of the protections. At power plants, in particular atomic ones, the number of current transformers is several hundred with different loads, lengths of supply cables and the implementation of relay protection. At the same time, the determination of the time to saturation is essential for the construction of circuits and principles of construction of relay protection systems and automation of power plants. The dynamic processes in the primary and secondary circuits of current transformers in dynamics are considered in detail. A mathematical description of the dynamic processes of a current transformer in the nominal mode and during a short circuit in its primary circuit is given. The substantiation of the expediency of using the hypothesis of a rectangular magnetization characteristic in simplified calculations of saturation processes is given. The possibility of using the characteristics of magnetization in the test protocols available in practice in the no-load mode to simulate saturation processes has been demonstrated. Simulation of current transformers for the no-load experiment and power supply of the current transformer from the secondary side, as well as during its operation under conditions of a short circuit on the primary side and a known load on the secondary side is carried out. Thus, with the help of a computer experiment, it is possible to take the current- voltage characteristics and transfer them to the model with the saturation of current transformers already in the short-circuit mode. The efficiency of dynamic simulation of current transformers is shown. The software implementation of the model is performed by means of structural simulation in the MatLab package, based on the solution of equations of matrix structures and emulation of parallel computations. It was found that with the adequacy of the model and the real current transformer with the involvement of information from the no-load mode, the determination of the magnetization time from the aperiodic current components from the model is much easier than the analysis by other existing methods. They require detailed design details of the current transformer and the magnetic properties of the steel.
9
Wang, Xiao Fang. "Transformer Inrush Current Identification Based on EMD+TEO Methods." Applied Mechanics and Materials 556-562 (May 2014): 3129–33. http://dx.doi.org/10.4028/www.scientific.net/amm.556-562.3129.
Full textAbstract:
Transformers is one of the most important power system components, its role is to carry power conversion and transmission, transformer manufacturing technology continues to develop, but there is a surge of its problems, factors that have caused the transformer inrush load switching, transformers string parallel operation and fault lines, etc, as a transformer inrush phenomenon often can lead to malfunction of its protection, the correct identification is particularly important means of this paper, the combination of EMD and TEO transformer inrush and fault operation effective identification, theory and simulation confirms the validity and reliability of the algorithm.
10
Cai, Wei, Lin Sun, and Hua Ren Wu. "Simulation of Transformer Protection Based on an Embedded MATLAB Function." Advanced Materials Research 960-961 (June 2014): 995–99. http://dx.doi.org/10.4028/www.scientific.net/amr.960-961.995.
Full textAbstract:
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.
11
Ivanchenko, Daniil, and Artem Smirnov. "Identification of interturn faults in power transformers by means of generalized symmetrical components analysis." E3S Web of Conferences 140 (2019): 04007. http://dx.doi.org/10.1051/e3sconf/201914004007.
Full textAbstract:
The paper deals with experimental identification of transformer internal faults, an important factor in reliability and sustainability of power supply systems. Task of identification of transformer internal faults requires increasing sensitivity of relay protection by calculation of components most sensitive to interwire faults from transformer current. In order to study internal faults in transformer, the model in Simulink MATLAB was developed on the basis of transformer constitutive equations. Transformer with short circuited wires was simulated as a multiwinding transformer. We provide the calculation of transformer parameters. Model was applied for analysis of transients in power transformers, such as interwire fault, transformer inrush, and fault in transformer connections. Analysis of power transformer internal faults by means of time-dependent symmetrical components of currents is provided. These symmetrical components were calculated for the first harmonic of current by means of discrimination of firs harmonic by low-pass filter and compensating elements implementing phase shift. Described method allows calculation of symmetrical components during transient and under non-sinusoidal conditions. Simulation results showed the advantage of instantaneous symmetrical components of other direct values. Those components were implemented in relay protection algorithms for identification of internal faults in transformers.
12
Konovalov, Yuriy, Lyudmila Tinina, and Liliya Naumova. "AUTOMATION OF THE SYSTEM OF PROTECTION OF THE POWER TRANSFORMER." Bulletin of the Angarsk State Technical University 1, no. 12 (December 18, 2018): 58–62. http://dx.doi.org/10.36629/2686-777x-2018-1-12-58-62.
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The article analyzes the main types of damage to power transformers, substantiates
the requirements for modern multifunctional microprocessor protection, proposed the technical implementation of the automation of protection of a power transformer.
13
Nisja, Indra. "Performance of current transformer operate under harmonic condition and their effects on transformer differential protection." MATEC Web of Conferences 159 (2018): 02075. http://dx.doi.org/10.1051/matecconf/201815902075.
Full textAbstract:
This paper focused to determine the performance of Current Transformer (CT) operates under harmonics condition and their effects on transformer differential protection. A laboratory test has been implemented to determine the error produced by both CT and power transformer when operating under harmonic condition. The test was performing with the actual condition, where the power transformer is connected to an adjusted nonlinear load, so that the test can be conducted with several levels of total harmonic distortion current (THDi). The results shows, for THDi ranging from 16.70% to 40.88% the maximum errors occurred on CT at secondary power transformers is 27.21% and CT at primary power transformers is 8.12%. This error resulted in differential current flow 0.17A and relay trip without any fault. In this study it was found that the relays started to operate incorrectly on THDi 31.5%.
14
Gurevich, Vladimir. "Protection of power transformers against geomagnetically induced currents." Serbian Journal of Electrical Engineering 8, no. 3 (2011): 333–39. http://dx.doi.org/10.2298/sjee1103333g.
Full textAbstract:
The article examines the problem of saturation and failure of power transformers under geomagnetically induced currents and currents of the E3 component of high-altitude nuclear explosions. It also describes a special protective relay reacting on DC component in the transformer neutral current.
15
Bejmert, Daniel, Klaus Boehme, Matthias Kereit, and Waldemar Rebizant. "HV Transformer Protection and Stabilization under Geomagnetically Induced Currents." Energies 13, no. 18 (September 9, 2020): 4693. http://dx.doi.org/10.3390/en13184693.
Full textAbstract:
This paper presents the results of research related to the issues arising from DC excitation of power transformers due to geomagnetically induced currents (GIC). First, the GIC phenomena and their influence on power system operation are discussed. Then, a recorded case of tripping of the transformer differential protection due to geomagnetic disturbances (GD), as well as simulation signals from a developed model of a transformer subjected to a GD are analyzed. Next, two algorithms for GIC detection utilizing the rate of change of transformer differential currents and the DC component in the neutral current are proposed, thoroughly tested, and recommended.
16
Wang, Fa Ming, Hao Sun, Yuan Chao Hu, Qi Jia Xie, and Wen Dai. "Study on the Key Technology of Intelligent Transformer." Applied Mechanics and Materials 278-280 (January 2013): 1005–10. http://dx.doi.org/10.4028/www.scientific.net/amm.278-280.1005.
Full textAbstract:
The development of smart grid puts higher requirement on the intelligentization of high-voltage equipment including transformers. At present, the intelligentization of transformers is mainly realized through intelligent components. The combination of intelligent components and transformer can realize the measurement, control, calculation, inspection and protection of the transformer. This paper detailedly described the hardware design framework and software function modules of transformer intelligent components, as well as the expert diagnosis system applied to transformer intelligent components. The intelligent components designed by this paper have been successfully applied to 220kV intelligent substation, which is operating stably and reliably. This can promote the development of intelligentized primary power equipment and smart grid as well.
17
Doletskaya, Larisa I., Vladislav I. Ziryukin, and Roman V. Solopov. "An electric power system object model creating experience for researching the operation of digital means of relay protection and automation." Journal Of Applied Informatics 16, no. 4 (August 31, 2021): 83–95. http://dx.doi.org/10.37791/2687-0649-2021-16-4-83-95.
Full textAbstract:
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.
18
Peng, Fang, and Houlei Gao. "Investigation into the Physical Mechanism and Influencing Factors of Sympathetic Inrush for Transformers in Series." Mathematical Problems in Engineering 2017 (2017): 1–11. http://dx.doi.org/10.1155/2017/9104707.
Full textAbstract:
Sympathetic inrush is a magnetizing inrush phenomenon generated in an in-service transformer, when a nearby transformer in series or in parallel is energized. This phenomenon lasts longer than the general inrush and can cause protection maloperation. The study focuses on sympathetic inrush in series transformers. Flux linkage expressions for the series transformers are derived using the Laplace transform. The residual flux, switching angle, and system impedance factors are included in the expressions. The physical mechanism of the sympathetic inrush for series transformers is explained based on the characteristics of the flux linkages. The interaction between the saturated transformers during sympathetic inrush is also investigated. Moreover, the influence of the switching angle, residual flux, system impedance, and load on the inrush currents is analyzed and validated.
19
Pourakbari-Kasmaei, Mahdi, and Matti Lehtonen. "Enhancing the Protective Performance of Surge Arresters against Indirect Lightning Strikes via an Inductor-Based Filter." Energies 13, no. 18 (September 11, 2020): 4754. http://dx.doi.org/10.3390/en13184754.
Full textAbstract:
Preventing the medium voltage (MV) transformer fault by protecting transformers against indirect lightning strikes plays a crucial role in enhancing the continuous service to electricity consumers. Surge arresters, if selected properly, are efficient devices in providing adequate protection for MV transformers against transient overvoltage impulses while preventing unwanted service interruptions. However, compared to other protective devices such as the spark gap, their prices are relatively high. The higher the surge arrester rating and energy absorption capacity are, the higher the prices go. This paper proposes an inductor-based filter to limit the energy pushed into the surge arrester, and consequently to prevent any unwanted failure. An energy-controlled switch is proposed to simulate the fault of the surge arrester. Surge arresters with different ratings, e.g., 12 kV, 18 kV, 24 kV, 30 kV, 36 kV, and 42 kV with two different classes of energy, namely, type a and type b, are tested under different indirect lightning impulses such as 100 kV, 125 kV, 150 kV, 175 kV, 200 kV, 250 kV, 300 kV, and 500 kV. Furthermore, these surge arresters are equipped with different filter sizes of 100 μH, 250 μH, 500 μH, and 1 mH. Results prove that equipping a surge arrester with a proper filter size enhances the performance of the surge arrester significantly such that a high rating and somewhat expensive surge arrester can be replaced by a low rating and cheap surge arrester while providing similar or even better protective performance for MV transformers. Therefore, such configurations not only enhance the protective capability of surge arrester, but also reduce the planning and operating costs of MV networks.
20
Azhari Zakri, Azriyenni, Mohd Wazir Mustafa, Hari Firdaus, and Ibim Sofimieari. "ASSESS THE RISK LEVEL OF POWER TRANSFORMER DUE SHORT-CIRCUIT FAULTS BASED ON ANFIS." SINERGI 23, no. 2 (July 12, 2019): 99. http://dx.doi.org/10.22441/sinergi.2019.2.002.
Full textAbstract:
A power transformer is an electrical machine that converts electrical power at different voltage levels. Faults, occur in power transformers, inhibit electrical power distribution to the consumer. Protection, therefore, of the power transformers is essential in power systems reliability. The power system can be reliable if the protection devices work well when there is a fault. A hybrid intelligent technique, which is a combination of Artificial Neural Network (ANN) and Fuzzy known as Adaptive Neuro-Fuzzy Inference Systems (ANFIS), was used in this research. The objective of this paper is the simulation of differential relays as a protection device on power transformers using Matlab/Simulink. Performance of differential relays for power transformers protection is carried out with internal and external fault scenarios. The input data were classified into three different input for ANFIS such as internal and external 1, internal and external 2, internal, external 1, and external 2, respectively. The error results of ANFIS training for the type of fault internal and external 1 is 9.46*10-7, and types of fault internal and external 2 is 1.09*10-6 internal, external 1 and external 2 are 8.59*10-7. The results obtained from the simulation were accurate and shows that the ANFIS technique is an efficient method that gives less error and a great value. Finally, the technique can minimize faults with power transformers. Finally, to prove this method can reduce faults in the power transformer, the assess of this model has been carried out through the RMSE that has been generated which is zero.
21
Mukhametgaleeva, T. S., and D. S. Fedosov. "A simplified model of a current transformer for studying relay protection operation in transient conditions." Proceedings of Irkutsk State Technical University 25, no. 4 (September 1, 2021): 450–62. http://dx.doi.org/10.21285/1814-3520-2021-4-450-462.
Full textAbstract:
We develop a simplified model of a current transformer based on its current-voltage characteristic. This model is applicable for studying relay protection operation in transient conditions when no high accuracy or consideration of current transformer magnet core hysteresis is required. The model was developed in MATLAB Simulink using elements of the SimPowerSystems and Simscape libraries. The model uses the transformation ratio and current-voltage characteristic obtained during operational tests of a current transformer. Calculation experiments with non-linear resistance found that a currentvoltage characteristic of voltage and current values can be used to model a current transformer, rather than instantaneous values. The following conditions were simulated: for nominal currents in current transformer windings to check the transformation ratio; for opened secondary winding; with current transformer saturation by increasing secondary loading; increasing the primary current ratio and presence of aperiodic current at the start of the transition process. It was found that the developed current transformer model allows for a correct imitation of all the above conditions. To verify the model, secondary current oscillograms were obtained using real current transformers 10 kV at known primary current, which were compared with nominal oscillograms in the model. The discrepancy between the results of calculational and real experiments was no more than 10% in amplitude values, with high-quality matching obtained for current charts in the model and real current transformers. A significant advantage of the developed model is that its setting requires no information on magnet core cross-section, power line length, steel grade, and the number of current transformer winding turns.
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Gunda, Sunil Kumar, and Venkata Samba Sesha Siva Sarma Dhanikonda. "Discrimination of Transformer Inrush Currents and Internal Fault Currents Using Extended Kalman Filter Algorithm (EKF)." Energies 14, no. 19 (September 22, 2021): 6020. http://dx.doi.org/10.3390/en14196020.
Full textAbstract:
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.
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Sihite, Josep Franklin, and Takehisa Kohda. "Power Transformers Condition Assessment of GI Simangkuk Switchyard Sumatra Interconnection in Indonesia." Advanced Materials Research 452-453 (January 2012): 975–79. http://dx.doi.org/10.4028/www.scientific.net/amr.452-453.975.
Full textAbstract:
The electricity needs of Indonesia grow an average 10% each year. Therefore, PLN (Perusahaan Listrik Negara) as the only power utility business in Indonesia, has a master plan to develop new power plant, switchyard and transmission system. One of the new developed systems is GI Simangkuk switchyard of Sumatra interconnection system. This switchyard is prepared to improve reliability of Sumatra interconnection system. This site utilizes power transformers of 275 kV. Power transformer is one of the main equipments in power systems. When a failure occurs in a power transformer, the whole system will be failed and the electricity could not be delivered to customer. Each utility has to assure their reliability in order to maintain electrical power system stability by assessing transformer condition. There is an increasing need for better diagnostic and monitoring tools to assess the condition of transformers. Modern power transformers are equipped with software and computer system control. The reliability of this computer systems are needed to evaluate for assurance of system safety. This paper describes the need of assessment and maintenance of power transformers such as outages effect of failures, high cost of maintenance and replacement, increase of world demand, aging effect and used of old transformer, and computer protection system failure. Monitoring and diagnostic methods of transformers assessment have been developing in recently years. They can be separated into traditional and non-traditional methods that have been used in many years and are still in research stage. In this paper we propose a new approach in order to assess power transformer condition by using fault tree analysis.
24
Zhang, Wei, and Lei Li. "The Protection Setting for 110kV Line Connects to V/V Traction Transformers." Advanced Materials Research 516-517 (May 2012): 1459–62. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1459.
Full textAbstract:
In 110kV railway traction the V/V connection transformers are common used. The distance protection performance for 110kV line connects to V/V traction transformer is analyzed in detail. Then some new advices on setting method for such kind of line protection calculation are proposed. This method is applied to several protection devices in Shandong power supply system. The operating result shows the accuracy of this method.
25
Popov, M. G., Yu N. Bocharov, E. I. Gurevich, F. H. Halilov, and V. V. Popov. "Dynamic methods of identification of electromagnetic parameters of power transformers in non-stationary mode." E3S Web of Conferences 91 (2019): 01002. http://dx.doi.org/10.1051/e3sconf/20199101002.
Full textAbstract:
The report reflects the promising solutions for the creation of adaptive protection means and emergency automatics in the implementation of methods of identification of dynamic systems. Presented original research assigned at directly addressing the causes of the sensitivity lack of the transformer equipment protection - compensation for the magnetizing current of the power transformers by linearizing their transfer characteristics.
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Quyen, Anh Huy, Thanh Phan Nguyen, Au Ngoc Nguyen, and Hung Ngoc Truong. "STUDY EFFECT OF LIGHTNING ARRESTERS IN TRANSFORMER PROTECTION, ACCOUNTING INFLUENTIAL FACTORS." Science and Technology Development Journal 12, no. 8 (April 28, 2009): 59–66. http://dx.doi.org/10.32508/stdj.v12i8.2275.
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The high voltage side of distribution transformers is usually protected against lightning surges by lightning arresters. In installation of lightning arresters, the separation distance between the lightning arrester and the high voltage bushing of transformer is importance factor. The new method for determination reasonable installation location of the lightning arrester, accounting technical - economic criteria and several influential factors such as the ground flash density, shielding factor, failure rate, lifetime of a transformer and earth resistance is presented in this paper. The installation of lighting arrester in 400kVA, 22/0.4kV distribution station in Ho Chi Minh City is also discussed and offered practical recommendations.
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Alibašić, Emir, Predrag Marić, and Srete N. Nikolovski. "Transient Phenomena during the Three-Phase 300MVA Transformer Energization on the Transmission Network." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 6 (December 1, 2016): 2499. http://dx.doi.org/10.11591/ijece.v6i6.11406.
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<p>Connecting the transformer to the network may incur inrush current, which is significantly higher than the rated current of the transformer. The main cause of this phenomenon lies in the nonlinearity of the magnetic circuit. The value of the inrush current depends of the time moment of the energization and the residual magnetism in the transformer core. While connecting, the operating point of the magnetization characteristic can be found deep in the saturation region resulting in occurrence of large transformer currents that can trigger the transformer protection. Tripping of protection immediately after the transformer energization raises doubts about the transformer health. Inrush current can cause a number of other disadvantages such as the negative impact on other transformers connected on the same busbar; the increase of the transformer noise due to the large current value, the increase of the voltage drops in the network. The paper presents a simulation of the 300 MVA transformer energization using the MATLAB/Simulink software.</p><p> </p><p> </p>
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Alibašić, Emir, Predrag Marić, and Srete N. Nikolovski. "Transient Phenomena during the Three-Phase 300MVA Transformer Energization on the Transmission Network." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 6 (December 1, 2016): 2499. http://dx.doi.org/10.11591/ijece.v6i6.pp2499-2505.
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<p>Connecting the transformer to the network may incur inrush current, which is significantly higher than the rated current of the transformer. The main cause of this phenomenon lies in the nonlinearity of the magnetic circuit. The value of the inrush current depends of the time moment of the energization and the residual magnetism in the transformer core. While connecting, the operating point of the magnetization characteristic can be found deep in the saturation region resulting in occurrence of large transformer currents that can trigger the transformer protection. Tripping of protection immediately after the transformer energization raises doubts about the transformer health. Inrush current can cause a number of other disadvantages such as the negative impact on other transformers connected on the same busbar; the increase of the transformer noise due to the large current value, the increase of the voltage drops in the network. The paper presents a simulation of the 300 MVA transformer energization using the MATLAB/Simulink software.</p><p> </p><p> </p>
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Ahmed, E., and R. El-Sehiemy. "A suggested differential protection scheme for power transformer." International Review of Applied Sciences and Engineering 5, no. 2 (December 1, 2014): 91–103. http://dx.doi.org/10.1556/irase.5.2014.2.1.
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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.
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Osintsev, Anatoly A., Aleksandra I. Naumova, and Elena I. Gracheva. "Analysis of distance protection’s operation in cases of deep saturation of current transformers." E3S Web of Conferences 288 (2021): 01095. http://dx.doi.org/10.1051/e3sconf/202128801095.
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There is usually no information about permissible error of current transformers in modes succeed by large relative short-circuit current, at which microprocessor-based protections operate stably. By this reason, it is necessary to use data, defined for analog relays. It leads to value appreciation of a project because it is often essential to reduce current transformers’ error in case of a short circuit fault. Therefore, it is necessary to define the value of current transformers’ error, permitted for impedance relays. Conclusions of fundamental and applied sciences (mathematical analysis, theoretical foundations of electrical engineering, theory of simulation), analytical methods of researching nonlinear circuits and digital signal processing were used. A simulation model was created for setting overall tests of the current trans-former (CT) system. It was a relay protection device that reflected all the important properties of studied objects and allowed an analysis of digital distance protection’s operation at high levels of short-circuit currents. The factors influ-encing over digital distance protection’s operation in case of deep saturation of CTs were revealed, and a certain algorithm for definition of the permissible CT errors was proposed. Stable operation of digital distance protection was observed in case of a fault nearby the place of current transformers’ setting in all theoretically possible combinations of electrical system’s power and length of a protected electric power transmission line. It is valid if electric load choice is carried with account for stable protection’s operation in condition of a fault in the computational point and if voltage swell in secondary wirings is infeasible.
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Sarajcev, Petar, Antun Meglic, and Ranko Goic. "Lightning Overvoltage Protection of Step-Up Transformer Inside a Nacelle of Onshore New-Generation Wind Turbines." Energies 14, no. 2 (January 8, 2021): 322. http://dx.doi.org/10.3390/en14020322.
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This paper presents an electromagnetic transient analysis of lightning-initiated overvoltage stresses of the step-up transformers installed inside a nacelle of onshore, multi-megawatt, new-generation wind turbines. The increase in the wind turbine (WT) nominal power output, necessitated introducing the step-up transformer into the nacelle. A transformer installed inside a nacelle is subjected to completely different overvoltage stresses from those present if it were installed at the base of the WT tower. This has serious repercussions on its overvoltage protection (i.e., selection and installation of surge arresters) and insulation coordination. Furthermore, the overvoltage protection of medium-voltage cables (inside the tower) is also problematic when considering their length, proximity to the tower wall, and their screen grounding practices, and needs to be tackled in conjunction with that of the step-up transformer. This paper presents detailed models for the various components of the latest-generation WTs, intended for fast-front transient analysis and assembled within the EMTP software package. We further present the comprehensive results of the lightning-transient numerical simulations, covering both upward and downward (first and subsequent) strikes, their analysis, and recommendations for the optimal selection of medium-voltage surge arresters for the step-up transformers installed inside a nacelle.
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Sarajcev, Petar, Antun Meglic, and Ranko Goic. "Lightning Overvoltage Protection of Step-Up Transformer Inside a Nacelle of Onshore New-Generation Wind Turbines." Energies 14, no. 2 (January 8, 2021): 322. http://dx.doi.org/10.3390/en14020322.
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This paper presents an electromagnetic transient analysis of lightning-initiated overvoltage stresses of the step-up transformers installed inside a nacelle of onshore, multi-megawatt, new-generation wind turbines. The increase in the wind turbine (WT) nominal power output, necessitated introducing the step-up transformer into the nacelle. A transformer installed inside a nacelle is subjected to completely different overvoltage stresses from those present if it were installed at the base of the WT tower. This has serious repercussions on its overvoltage protection (i.e., selection and installation of surge arresters) and insulation coordination. Furthermore, the overvoltage protection of medium-voltage cables (inside the tower) is also problematic when considering their length, proximity to the tower wall, and their screen grounding practices, and needs to be tackled in conjunction with that of the step-up transformer. This paper presents detailed models for the various components of the latest-generation WTs, intended for fast-front transient analysis and assembled within the EMTP software package. We further present the comprehensive results of the lightning-transient numerical simulations, covering both upward and downward (first and subsequent) strikes, their analysis, and recommendations for the optimal selection of medium-voltage surge arresters for the step-up transformers installed inside a nacelle.
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Pourakbari-Kasmaei, Mahdi, Farhan Mahmood, Michal Krbal, Ludek Pelikan, Jaroslava Orságová, Petr Toman, and Matti Lehtonen. "Evaluation of Filtered Spark Gap on the Lightning Protection of Distribution Transformers: Experimental and Simulation Study." Energies 13, no. 15 (July 24, 2020): 3799. http://dx.doi.org/10.3390/en13153799.
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Protection of transformers, as one of the most expensive equipment in the power system, against lightning overvoltage impulses is a vital task. This paper, for the first time so far, investigates the effects of a filtered spark gap on the protection level of transformers against lightning overvoltage impulses. The filter is an inductor that is placed in series with the transformer and before the spark gap aiming to reduce the voltage at the connection point of the spark gap, and hence, enhancing the protection level of the transformer under lightning overvoltages. The experimental laboratory tests are accomplished on a 400 kVA, 22/0.4 kV, Delta-Star ( Δ − Y ) connection type transformer under 110 kV, and 125 kV overvoltage impulses, whereas the size of the spark gap is set to 80 mm and two inductors of 35 μ H and 119 μ H are considered. In order to perform a more in-depth analysis, a model that works reasonably close to the empirical case is developed in the EMTP-RV software. An optimization algorithm is used to determine the sensitive parameters of the double-exponential function, which is used to reproduce the applied laboratory lightning impulse voltages in the EMTP-RV environment. Moreover, the transformer is modeled according to the Cigre Guidelines (Working Group 02 of Study Committee 33). The behavior of the spark gap is simulated as close as the practical situation using the disruptive effect method. The preciseness of the simulated filtered spark gap model is verified by comparing the results of the simulated model in the EMTP-RV with the results of experimental tests. After verifying the model, different sizes of inductors are studied in the EMTP-RV environment to investigate whether larger or smaller inductors provide better protection for the transformer under lightning conditions. A comparison is performed among the conventional spark gap, surge arrester, and the filtered spark gap to provide a better analysis of the potential of the proposed device. The results indicate that proper sizing of the inductor, within an effective range, slightly enhances the protection level of the transformer.
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Teruo Mendes de Souza, Diego, Bruno Valverde, and José Antenor Pomilio. "OVERVOLTAGE PROTECTION FOR HIGH FREQUENCY HIGH VOLTAGE POWER TRANSFORMERS." Eletrônica de Potência 25, no. 1 (February 5, 2020): 125–34. http://dx.doi.org/10.18618/rep.2020.1.0045.
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Onah, Aniagboso John, and Edwin Ejiofor Ezema. "Transformer Differential Protection." European Journal of Engineering Research and Science 5, no. 8 (August 21, 2020): 891–98. http://dx.doi.org/10.24018/ejers.2020.5.8.2035.
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Overcurrent and earth fault protective equipment employing time grading and directional detection cannot provide correct discrimination on all power networks and in many cases clearing times for some faults would not be acceptable. Differential protection is an alternative overcurrent protective scheme, which is used to protect individual sections of networks or pieces of equipment, such as transformers, generators, e.t.c. Thus, where protection co-ordination is difficult using time delayed over current and earth fault protection, or where fast fault clearance is critical, then differential protection may be used. Kirchhoff’s first law, which states that the sum of the currents flowing to a node must be equal to the sum of the currents flowing out from it is the basic principle of the differential protection scheme. It detects the difference between the current entering a section and that leaving it. Under normal operating conditions, the current leaving the protected unit would be equal to that entering it at every instant. If the current flowing into the protected unit is the same as the current leaving, then the fault is not in the protected unit and the protective equipment or relay should not operate. If there is a difference in either the phase or magnitude between input and output, then the fault is in the protected unit and the protection should operate. This paper investigates how power transformers can be protected using the current-differential protection schemes.
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Florkowski, Marek, Jakub Furgał, Maciej Kuniewski, and Piotr Pająk. "Overvoltage Impact on Internal Insulation Systems of Transformers in Electrical Networks with Vacuum Circuit Breakers." Energies 13, no. 23 (December 2, 2020): 6380. http://dx.doi.org/10.3390/en13236380.
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Vacuum circuit breakers are increasingly used as switching apparatus in electric power systems. The vacuum circuit breakers (VCBs) have very good operating properties. VCBs are characterized by specific physical phenomena that affect overvoltage exposure of the insulation systems of other devices. The most important phenomena are the ability to chop the current before the natural zero crossing, the ability to switch off high-frequency currents, and the rapid increase in dielectric strength recovery. One of the devices connected directly to vacuum circuit breakers is the distribution transformer. Overvoltages generated in electrical systems during switching off the transformers are a source of internal overvoltages in the windings. The analysis of the exposure of transformers operating in electrical networks equipped with vacuum circuit breakers is of great importance because of the impact on the insulation systems of switching overvoltages (SO). These types of overvoltages can be characterized by high maximum values and atypical waveforms, depending on the phenomena in the circuit breaker chambers, system configuration, parameters of electrical devices, and overvoltage protection. Overvoltages that stress the internal insulation systems are the result of the windings response to overvoltages at transformer terminals. This article presents an analysis of overvoltages that stress the transformer insulation systems, which occur while switching off transformers in systems with vacuum circuit breakers. The analysis was based on the results of laboratory measurements of switching overvoltages at transformer terminals and inside the winding, in a model medium-voltage electrical network with a vacuum circuit breaker.
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Kuprienko, Viktor. "Bias signal control in differential protection." MATEC Web of Conferences 212 (2018): 01035. http://dx.doi.org/10.1051/matecconf/201821201035.
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The problem is to ensure the stability of the differential protection functioning at deep saturation of the cores of electromagnetic current transformers. The errors of current transformers support the greatest influence on the operation of differential protections. Features of the differential protection operation at deep saturation of current transformers in short-circuit transient modes are considered. Comparison results of various algorithms for the formation of a bias signal are given. The control capability of the bias signal generation algorithm was analyzed. The harmonic composition of the differential current on the mathematical model of two-arm differential protection in the transient mode with external and internal short circuits at saturation of the current transformers of one arm was investigated. The stability of the differential protection functioning can be enhanced by the selectivity of the bias signal generation algorithm. A bias signal control criterion using a relative level of higher harmonics to a differential signal was proposed.
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Sule, I. "Simulation Model for Assessing Operational Performance of Current Transformers." Advanced Materials Research 18-19 (June 2007): 71–77. http://dx.doi.org/10.4028/www.scientific.net/amr.18-19.71.
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In determining the correct operation of relays of a protection scheme, proper representation of instrument transformers and their behavior in conditions where there can be saturation, is very critical. The main objective of this paper is to develop simulation model for assessing the operational performance of Current Transformer (CT). In order to test the validity of the developed model, three cases of CT operational conditions were considered, with data collected from Gombe, 330/132/33kV PHCN substation. The simulation results revealed various configuration performance responses that could affect relay protective schemes to different degrees. The CT responses revealed that the secondary current and voltage were distorted when the core flux linkages exceeded the set 9.2 pu saturation limit. It is concluded that the model developed for the CT of interest yield satisfactory results.
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Sharma, Anand, Dr Deepika Chauhan, and Vijay Kumar Mahawar. "A Review on Various Methods of Transformer Protection." International Journal of Trend in Scientific Research and Development Volume-2, Issue-3 (April 30, 2018): 1108–12. http://dx.doi.org/10.31142/ijtsrd11267.
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Jurnal, Redaksi Tim. "ANALISA PROTEKSI DIFFERENSIAL PADA GENERATOR DI PLTU SURALAYA." Energi & Kelistrikan 9, no. 1 (November 26, 2018): 84–92. http://dx.doi.org/10.33322/energi.v9i1.51.
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Power plants produce electrical energy that will be distributed to consumers. Hence, the power plant is expected to be in a condition which means it can reliably provide electricity continuously with good quality. So as to improve the reliability and continuity of service, the operation of power systems require a safety equipment or protection system to prevent disturbances that disrupt the system. Protection system is an important component to maintain the continuity and reliability of the distribution of electrical energy. Protection system serves to protect equipment from damage in the event of disturbances and minimize disruptions from spreading. With good protection system, the unwanted loss can be avoided, especially in the vital equipment such as generators and transformers. One of the equipment that plays a role in the protection system is a differential protection relays are used to protect generators and transformers. This relay protects the generator and transformer from internal disturbances such short circuit between phases or short circuit of phase to ground. This rele works based on the current setting and operating time has been determined so that it can work quickly and precisely targeted.
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Bernadić, Alen, and Zahira Anane. "NEUTRAL POINT CONNECTIONS IN MV POWER NETWORKS WITH GROUNDING ZIGZAG TRANSFORMERS – ANALYSIS AND SIMULATIONS." Journal of Energy - Energija 68, no. 1 (April 30, 2019): 42–48. http://dx.doi.org/10.37798/20196812.
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Treatment of transformer neutral point in middle-voltage (MV) networks become an important issue with increasing proportion of MV cables in power networks. As consequence, overall capacitance of MV network is increased and moreover earth fault currents magnitudes. In MV networks with feeding transformer winding in delta connection (isolated networks), that earth fault current increase requires forming of artificial ground point – a neutral connection point on a three-phase ungrounded power system. Grounding transformer use, in zigzag or delty-wye connection, is common, well-known solution for constructing neutral connection in power systems. Physical characteristics of grounding transformers, protection principles, short-circuit calculations with symmetrical components and simulation techniques are presented in this paper. Characteristical operational modalities of MV power networks are also revieved on practical examples.
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Vukolov, V. Yu, A. A. Petrov, S. N. Yurtaev, and R. Sh Bedretdinov. "Development of universal algorithm of voltage circuits detecting faults of microprocessor protection and automation devices." Vestnik IGEU, no. 3 (June 30, 2021): 33–41. http://dx.doi.org/10.17588/2072-2672.2021.3.033-041.
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Reliability, along with response speed, sensitivity, and selectivity, is the key requirement for relay protection (RP) devices. The reliability of modern RP digital terminals is understood as protection operation for all estimated failure modes and failure of protection equipment to operate in all other modes, in which this protection is not provided. Analysis of the secondary voltage schemes and algorithms of detecting faults in these circuits reveals several disadvantages of the implementation of blocking in case of faults in voltage circuits. All existing algorithms and blocking schemes in case of faults in voltage circuits suffer from several disadvantages. In this regard, it is relevant to develop a universal relay protection terminal, which can be used with any types of voltage transformers. The MatLAB Simulink is used to simulate the primary failure of secondary circuits for the connection schemes of the voltage transformer load on phase and electric line voltages. The authors propose the algorithm that allows us to create a typical universal RP terminal, which can be used with any type of voltage transformers. To detect the neutral conductor interruption of the «star» circuits, it is proposed to create an artificial asymmetry at the input voltage circuits of the relay protection and automation (RPA) terminal and develop a group of fault detectors that analyze the position of the offset neutral on the voltage complex plane. Using a simulation model of various types of failure of voltage transformer secondary circuits and the logic diagram of the unit that implements the proposed algorithm, the authors graphically show that the detection of a break in the neutral wire is possible due to monitoring the zero-sequence voltage spike (triggering of the pulsed dU0 fault detector) with neutral displacement to the complex plane area, which is set by the setpoints. The results obtained allow us to implement a universal scheme of blocking faults in voltage circuits. This scheme does not depend on the voltage transformer secondary load connection method and exclude the disadvantages of existing solutions discussed in the article. This algorithm allows us to develop a typical universal RPA terminal. Due to its connection scheme and functional and logical implementation, this terminal can be used with any types of voltage transformer without reprogramming. Also, the proposed algorithm fully complies with the requirements of the current regulatory and legal documents.
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Mayer, Daniel. "Protection of power transformers against the effect of magnetic storms." Journal of Electrical Engineering 72, no. 4 (August 1, 2021): 249–55. http://dx.doi.org/10.2478/jee-2021-0034.
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Abstract In the operation of large-scale power systems for the long-distance transmission of large amounts of electricity, a number of cases have been reported in which anomalies in the Earth’s magnetosphere, referred to as geomagnetic storms, have caused a severe system collapse. Changes in the geomagnetic field cause a semi-saturating phenomenon, in which the high-voltage lines and especially the high-voltage windings of the power transformers of the system are overloaded with current and subsequently also thermally. The present article briefly explains the physical nature of magnetic storms and then describes a new device that either eliminates the possibility of a step-down power transformer accident or significantly reduces its effects on the system. The essence of this device are frequency filters, which are connected in parallel to the high-voltage windings of power transformers. At the beginning of a geomagnetic storm, the frequency filter is automatically connected to the system and is automatically disconnected when it subsides. The operation of frequency filters does not require human intervention, acquisition and operating costs are low and their integration into existing power systems is easy.
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Yu, Jicheng, Changxi Yue, Jun Li, Dengyun Li, and He Li. "Error Calculating and Compensating Method of All-Optical Fiber Current Transformer in ± 10 kV DC Distribution Network." Journal of Nanoelectronics and Optoelectronics 14, no. 11 (November 1, 2019): 1606–15. http://dx.doi.org/10.1166/jno.2019.2680.
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Current transformer is one of the main equipment in ±10 kV DC distribution network. Traditional electromagnetic current transformer has poor anti-jamming capacity and poor insulation, so it cannot realize transient protection. The emergence of all-optical fiber current transformer brings solutions to these problems, which has attracted more and more attention. In this study, aiming at the problem of error and compensation of λ/4 waveform of all-fiber current transformer, the fabrication method of λ/4 waveform is studied, the mathematical model of the waveform is established, the influence of the waveform error on the scale factor is analyzed, and a calculating device of angle difference and ratio difference to compare the error is designed. The device adopts the principle of traceability of quantities to collect the state data of the wave plate. At the same time, in order to collect data for errors, database technology and network technology are used to realize remote transmission of monitoring data. The error of the λ/4 wave plate is compensated, the bidirectional principle generated by the birefringence in the fiber ring is analyzed, and the data logic description of the transformer sensitive ring is performed. The phase delay and the angle of the shaft are selected as the main factors causing the error. Compensation is performed by means of peak segmentation and variable cancellation. In the experimental process, compared with the error sampling of the traditional transformer, the error calculated by the current amplitude and phase angle parameters obtained by the all-fiber current transformer is more accurate, and the compensation scheme can suppress the size of the birefringence and improve sensing accuracy of fiber optic current transformers. This study provides a powerful reference for the error analysis of all-fiber current transformer λ/4 wave plates, which is beneficial to promote the better application of such current transformers.
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Bin Yaacob, Mohd Muhridza, Ahmed Raisan Hussein, and Mohd Fauzi Bin Othman. "DGA Method-Based ANFIS Expert System for Diagnosing Faults and Assessing Quality of Power Transformer Insulation Oil." Modern Applied Science 10, no. 1 (December 20, 2015): 13. http://dx.doi.org/10.5539/mas.v10n1p13.
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<p class="zhengwen"><span lang="EN-GB">Accurate fault diagnostics and assessment of electrical power transformer insulation oil for lifelong endurance are the key issues addressed in this research. The durability of a transformer is significantly determined by the quality of its insulation oil, which deteriorates over time due to temperature fluctuations and moisture content. Protecting transformers from potential failure through early and precise diagnosis of faults and through efficient assessment of oil quality during the actual conduct of the operation can avoid sizeable economic losses. The ANFIS Expert System that uses intelligent software plays an important role in this regard. The dissolved gas analysis (DGA) in oil is a reliable method for diagnosing faults and assessing insulation oil quality in transformers. The safeguarding teams of transformer power stations often suffer from the occurrence of sudden faults, which result in severe damages and heavy monetary loss. The oil in transformers must be appropriately treated to circumvent such failures. In this research, an ANFIS Expert System was used to diagnose faults and to assess the status and quality of insulation oil in power transformers. A suitable treatment was identified using the Rogers ratio method depending on the DGA in oil. The graphical user interface from the MATLAB environment was used and proven effective for fault diagnosis and oil quality evaluation. The training algorithm is capable of assessing oil quality according to the specifications of the IEEE standard C57-104 and the IEC standard 60599.</span></p>
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Namdari, Farhad, Mohammad Bakhshipour, Behroz Rezaeealam, and Mohammad Sedaghat. "Modeling of Magnetizing Inrush and Internal Faults for Three-Phase Transformers." International Journal of Advances in Applied Sciences 6, no. 3 (September 1, 2017): 203. http://dx.doi.org/10.11591/ijaas.v6.i3.pp203-212.
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Among the most noticeable root causes of improper performance in power transformers, internal short circuit faults can be noted and if not quickly be identified and addressed in the accepted time interval, irrecoverable damages such as interruption or even collapse of the network connected to the power transformer would happen. In this contribution, three-phase transformer behaviors under magnetizing inrush, internal short circuit condition and their current values determination have been surveyed using electromagnetic coupling model approach and structural finite element method. Utilizing the definition of transformer in the form of multi-coil and their electromagnetic and electric couple, a three dimensional geometric model of transformer is developed which includes nonlinear characteristics of the transformer, different states of normal and under internal short circuit occurrence and the moment of magnetizing inrush creation are investigated. The comparison between obtained results of presented model simulation with the consequences of practical studies on a typical three phase transformer reveals that the proposed model has a reliable accuracy in detection and modelling the transformer behavior in normal conditions, magnetizing inrush and different types of internal faults. The proposed approach represents an accurate model of a three-phase transformer for protection aims.
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Bakhshipour, Mohammad, Farhad Namdari, and Mohammad Sedaghat. "Modeling of Magnetizing Inrush and Internal Faults for Three-phase Transformers." Indonesian Journal of Electrical Engineering and Computer Science 3, no. 1 (July 1, 2016): 26. http://dx.doi.org/10.11591/ijeecs.v3.i1.pp26-37.
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Among the most noticeable root causes of improper performance in power transformers, internal short circuit faults can be noted and if not quickly be identified and addressed in the accepted time interval, irrecoverable damages such as interruption or even collapse of the network connected to the power transformer would happen. In this contribution, three-phase transformer behaviors under magnetizing inrush, internal short circuit condition and their current values determination have been surveyed using electromagnetic coupling model approach and structural finite element method. Utilizing the definition of transformer in the form of multi-coil and their electromagnetic and electric couple, a three dimensional geometric model of transformer is developed which includes nonlinear characteristics of the transformer, different states of normal and under internal short circuit occurrence and the moment of magnetizing inrush creation are investigated. The comparison between obtained results of presented model simulation with the consequences of practical studies on a typical three phase transformer reveals that the proposed model has a reliable accuracy in detection and modelling the transformer behavior in normal conditions, magnetizing inrush and different types of internal faults. The proposed approach represents an accurate model of a three-phase transformer for protection aims.
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Yao, Jianfu, Lu, Zhanqing, Zipan, and Rong. "Research on Access Mode of the Flexible DC Power Distribution System into AC System." Energies 12, no. 20 (October 21, 2019): 4002. http://dx.doi.org/10.3390/en12204002.
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The connection mode of the direct current (DC) power distribution system and the alternating current (AC) system is the foundation of system design, and it is also one of key technologies of the DC power distribution network. Based on the topology structure, grounding method, main equipment parameters, load parameters and system control protection strategy of the DC power distribution system, this paper establishes the system simulation model in the case of configuring the connection transformer and not configuring the connection transformer. Simulation results show that, when no connecting transformer is installed, the interaction between AC and DC systems will be great when faults occur, and the cost of converter valves and DC reactors will be increased. When connecting transformers are installed, the interaction between AC and DC systems can be effectively isolated, and the operation reliability of the system will be greatly improved while the cost is saved. Therefore, it is recommended to configure an independent connection transformer in the DC distribution system.
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V Swathi, G., N. Paparao, and D. Swathi. "Design an Efficient Power Electronics Transformer (PET) for the Improvement of Quality in Power." International Journal of Engineering & Technology 7, no. 3.12 (July 20, 2018): 1046. http://dx.doi.org/10.14419/ijet.v7i3.12.17629.
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This paper consists of a new device called as Power Electronics transformer (PET) which has been recommended in paper so that it understands that voltage transformation, galvanic isolation, and enhancing force personal satisfaction for a just gadget. The PET gives a complete methodology for designing a transformer that uses Power electronic frameworks which comprises for primary coil and auxiliary coils of a transformer. A couple features to example, such-and fast voltage regulation, voltage list recompense what's more likewise revision for control figure could a chance to be united under PET. This paper indicates another thought of plotting An vitality electronic transformer. In the schema process, those AC/DC, DC/AC, AC/AC converters In addition secondary back transformers have been utilized. Grid converter similarly meets desires Likewise AC/AC converter on force electronic transformer. Those proposed drive electronic transformer performs perplexedly capacities to example, amendment regarding energy. Factors, elimination of swell and voltage sag, reduction of voltage flicker and fault situation protection capabilities. The recommended force electronic transformer need been shown using MATLAB/ SIMULINK Furthermore also change Previously, force characteristic with recommended perfect gas need been checked by the simulink outcomes.
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Alyunov, Alexander, Olga Vyatkina, and Alexander Nemirovskiy. "On efficiency of digital system of power transformer proactive diagnostics." Proceedings of Irkutsk State Technical University 24, no. 5 (October 2020): 966–76. http://dx.doi.org/10.21285/1814-3520-2020-5-966-976.
Full textAbstract:
The purpose of the paper is to diagnose the state of a power transformer by determining its equivalent circuit parameters by means of synchronized vector measurements of currents and voltages in the transformer normal operation mode without shutdowns, which makes it possible to increase the reliability of relay protection operation. A cost - effective method for proactive diagnostics of power transformers is proposed. Through monitoring of additional parameters (short circuit resistance, active and inductive resistance of the positive sequence, active and inductive resistance of the negative sequence) it can increase the speed and accuracy of detecting possible internal short circuits arising due to winding damage or high-voltage transformer bushings without diagnosed transformer disconnection from the network. The method allows to estimate the transformer health index and serviceability by the difference between the calculated parameters of the equivalent circuit and the passport values of the parameters. Having conducted the damage causedependent analysis of the number of power transformer damages, the authors determined total economic losses that include the losses caused by equipment damage and losses caused by the interruptions in consumer power supply. The total economic losses for a power transformer with a rated power of 63 MVA amounted to 10687402 rubles. It is shown that the diagnostic system expands the possibilities of analyzing the transformer state in operating modes, allows to pr event the approaching of the damage moment and occurrence of sudden accidents as well as minimizes the expected damage from shutdowns and equipment failure. A hardware and software complex is proposed for the diagnostics of power transformer internal damage. The given main characteristics of the proposed hardware and software complex include the number of measuring channels, accuracy class, sampling frequency, and others. The results of the work expand the possibilities of analyzing the transformer state in the operating mode and can be used in the world practice of creating various monitoring systems designed to identify the defects developing in transformers caused by winding deformation.