The Triple-Harmonic Equivalent Circuit in Three-Phase Power Transformer Banks

1933 ◽  
Vol 52 (1) ◽  
pp. 64-71 ◽  
Author(s):  
Theodore H. Morgan ◽  
Cyril A. Bairos ◽  
Gordon S. Kimball
Keyword(s):  
Equivalent Circuit ◽  
Power Transformer ◽  
Three Phase

Equivalent circuit modelling of a three-phase to seven-phase transformer using PSO and GA

2021 ◽  
pp. 1-10 ◽  
Author(s):  
Md Tabrez ◽  
Atif Iqbal ◽  
Pradip Kumar Sadhu ◽  
Mohammed Aslam Husain ◽  
Farhad Ilahi Bakhsh ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Equivalent Circuit ◽  
Power Transformer ◽  
Optimization Technique ◽  
Proposed Model ◽  
Three Phase ◽  
Unequal Number ◽  
Optimized Model ◽  
Secondary Side ◽  
Circuit Modelling

Impedance mismatching between different phases of a multiphase transformer is generally observed e.g., in a three-phase to seven-phase transformer, due to an unequal number of turns in different coils. This mismatching introduces error in the study of per phase equivalent circuit diagrams as well as induces an imbalance in output voltages and currents. Therefore, it is a challenging task to develop a per-phase equivalent circuit for the secondary and primary sides (In some cases) too. This paper proposes an artificial intelligence optimization technique like PSO based modeling of the per-phase equivalent circuit of the secondary side. This paper deals with the modeling and simulation of a three-phase to seven-phase power transformer using Artificial Intelligence technique like particle swarm optimization (PSO) and Genetic Algorithm (GA). The proposed model is optimized through PSO and GA algorithms and tested for minimum voltage error in each phase. The proposed model is designed and the objective function is optimized by PSO & GA in MATLAB environment. It is found that the optimized model can be effectively implemented as a per-phase equivalent circuit for the secondary side.

scholarly journals Turn-to-Turn Fault Diagnosis on Three-Phase Power Transformer Using Hybrid Detection Algorithm

2021 ◽  
Vol 11 (6) ◽  
pp. 2608
Author(s):  
Chien-Hsun Liu ◽  
Willybrordus H. P. Muda ◽  
Cheng-Chien Kuo
Keyword(s):  
Fuzzy System ◽  
Power Transformer ◽  
Detection Algorithm ◽  
Current Response ◽  
Negative Sequence ◽  
Three Phase ◽  
Hybrid Detection ◽  
Incipient Faults ◽  
Increase In Accuracy ◽  
Negative Sequence Current

A power transformer (PT) in power generation or transmission is critical to maintaining electrical continuity. Fault detection on a PT is needed, especially of incipient faults, which are often caused by a turn-to-turn fault (TTF) before it develops into a more severe fault. We use a hybrid algorithm between conventional and modern techniques to detect a developing fault in a PT. The current response signals from a negative sequence current directional algorithm, extended park vector algorithm (EPVA), differential negative sequence current, and EPVA-fuzzy system are combined to distinguish the possibility of a TTF. The subalgorithms are combined using a hybrid detection algorithm to distinguish the faults. The model is a 10 MVA, three-phase PT with Δ-Y configuration 150/300 kV, simulated using MATLAB Simulink software. The results show that by combining the subalgorithms, several limitations are distinguished within the TTF with a slight increase in accuracy.

scholarly journals Faults diagnosis in stator windings of high speed solid rotor induction motors using fuzzy neural network

2021 ◽  
Vol 12 (1) ◽  
pp. 597
Author(s):  
Ahmed Thamer Radhi ◽  
Wael Hussein Zayer
Keyword(s):  
Neural Network ◽  
Equivalent Circuit ◽  
High Speed ◽  
Fuzzy Neural Network ◽  
Induction Motors ◽  
Stator Winding ◽  
Three Phase ◽  
Fuzzy Neural ◽  
Diagnosis Method ◽  
Faults Diagnosis

The paper deals with faults diagnosis method proposed to detect the inter-turn and turn to earth short circuit in stator winding of three-phase high-speed solid rotor induction motors. This method based on negative sequence current of motor and fuzzy neural network algorithm. On the basis of analysis of 2-D electromagnet field in the solid rotor the rotor impedance has been derived to develop the solid rotor induction motor equivalent circuit. The motor equivalent circuit is simulated by MATLAB software to study and record the data for training and testing the proposed diagnosis method. The numerical results of proposed approach are evaluated using simulation of a three-phase high-speed solid-rotor induction motor of two-pole, 140 Hz. The results of simulation shows that the proposed diagnosis method is fast and efficient for detecting inter-turn and turn to earth faults in stator winding of high-speed solid-rotor induction motors with different faults conditions

scholarly journals Enhancement of the Thermal Performance Characteristics of an Electrical Power Transformer

2020 ◽  
pp. 94-112
Author(s):  
Nawras Mohammed Azbar ◽  
Hayder Mohammad Jaffal ◽  
Basim Freegah
Keyword(s):  
Thermal Performance ◽  
Thermal Load ◽  
Model Comparison ◽  
Experimental Finding ◽  
Power Transformer ◽  
Electrical Power ◽  
Operational Parameters ◽  
3D Numerical Simulation ◽  
Cooling Performance ◽  
Three Phase

A 3D numerical simulation was conducted to test the effects of the geometrical and operational parameters on the cooling performance of a three-phase electrical distribution transformer (250 kVA oil natural air natural (ONAN)). The geometric parameters include the shape of the transformer (rectangular, circular, and hexagonal), fins shape (rectangular, semicircular, and trapezoidal) as well it arrangement (asymmetric fin heights and perforated fins). Both of oil temperature and thermal load have been used as boundary conditions. In order to verify the reliability of the numerical model, comparison between numerical results and experimental finding has been done. The results have indicated that the circular and hexagonal shapes reduced the average oil temperature by 3.4% and 4.7%, respectively, compared to the traditional transformer shape (rectangular). Furthermore, the lowest average oil temperature was observed for the trapezoidal fin, followed by the rectangular and semicircular fins. Additionally, it has been noticed that the asymmetric fin heights of the trapezoidal and perforated trapezoidal fins been contributed to the improvement of the cooling performance of the transformer. Furthermore, the best thermal performance was obtained with the trapezoidal perforated fin to compared other arrangement of fins. Finally, the highest reduction in oil has been obtained by the use of hexagonal transformer with a perforated trapezoidal fin approximately by 12% compared to traditional rectangular transformer. Hence, it can be concluded that the shape of the transformer and fins play an important role in thermal performance of such systems.

The Poynting Vector and the New Theory of a Transformer. Part 11. Three-Phase Three-Core Transformers without a Neutral Wire

2021 ◽  
Vol 1 (1) ◽  
pp. 23-34
Author(s):  
Mansur A. SHAKIROV ◽  
Keyword(s):  
Equivalent Circuit ◽  
Single Phase ◽  
Poynting Vector ◽  
Magnetic Circuit ◽  
Phase Zone ◽  
Field Patterns ◽  
Three Phase ◽  
Short Circuits ◽  
The Difference ◽  
Mathematical Relations

A topological equivalent circuit for a three-phase three-core transformer reflecting the spatial structure of its magnetic system is developed. Owing to this approach, it became possible to represent the magnetic fluxes of the magnetic circuit’s all main sections and the apertures for each of three phases directly in the circuit in the absence of the windings’ neutral wires. The circuit is constructed by stitching together the anatomical circuit models of single-phase transformers obtained in the previous parts with taking into account the relationships between the fluxes at the junctions of the phase zones in iron. Its validity is confirmed by the rigor nature of the physical and mathematical relations for idealized transformers with infinite magnetic permeability of iron and simplified magnetic field patterns, which corresponds to the generally accepted approach with neglecting the magnetization currents. The difference lies in the fact that the developed model takes into account the heterogeneity of magnetization in different parts of the magnetic circuit with allocating more than 30 sections in the iron and apertures. The transition to the model of a real three-core transformer is carried out by adding four nonlinear transverse magnetization branches in each extreme phase zone and eight branches in the central phase zone to the idealized equivalent circuit. It is shown that in cases of winding connections without neutral wires, there is no flux of the Poynting vector in interphase zones in any unbalanced mode. In this case, the problems connected with the occurrence of fluxes exceeding the no-load fluxes under the conditions of symmetric and asymmetric short circuits, as well as the occurrence of buckling fluxes in these modes in the region outside the transformer iron, are solved.

scholarly journals Open-Loop Single-Phase Space State Model and Equivalent Circuit of a Non-Conventional Three-Phase Inverter

Electronics ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 744
Author(s):  
Vinícius Melo ◽  
Alexandre Melo ◽  
Walbermark Santos ◽  
Jussara Fardin ◽  
Lucas Encarnação
Keyword(s):  
Equivalent Circuit ◽  
Direct Current ◽  
Single Phase ◽  
Green Energy ◽  
State Model ◽  
Phase Inverter ◽  
Three Phase ◽  
Space State ◽  
Phase Models ◽  
Three Phase Inverter

Recently, many non-conventional three-phase inverters, topologies for green energy source grid-connection systems, and electric drives have been proposed. Simplifying the inverter circuit is crucial to analyze and solve their models in order to design them. The main goal of the study is centered on obtaining a single-phase equivalent circuit and space state model from non-conventional three-phase inverters based on bidirectional direct current–direct current (DC–DC) Buck-Boost topology using isolated gate bipolar transistors (IGBT). From just one phase of the three-phase inverter, the single-phase equivalent circuit was obtained by means of Kirchhoff’s laws. The equivalent circuit operation steps were presented in order to obtain the space state model. Finally, the equivalent circuit was simulated, and experimental results with a 200 W three-phase inverter feeding a resistive, inductive, and capacitive loads were performed to confirm the theoretical and simulation analyses. The results show the state space dynamic behavior variables of single-phase and three-phase models are quite similar. Therefore, it can be concluded that the proposed circuit can be used with property to represent equivalent single-phase models of non-conventional three-phase inverters.

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