Mehdi Bigdeli

Islamic Azad University | IAU · Department of Electrical Engineering

Frequency response analysis (FRA) is considered as the most popular and reliable method to detect mechanical deformations within power transformers. Despite this popularity, interpretation of FRA signatures has not yet been standardized worldwide. Correct interpretation of FRA signatures results in reliable diagnosis of the transformer mechanical i...

Moisture in the transformer insulation can shorten its life. There are many methods for detecting humidity in transformer paper insulation. One of the methods used in the factory to evaluate the drying process of transformer insulation and determine its humidity is the frequency response analysis method. In this paper, the desired experiments are p...

Purpose This paper aims to evaluate the effect of optimal use of rooftop photovoltaic (PV) systems on improving the loss of life (LOL) of distribution transformers, reducing power losses as well as the unbalance rate of the 69-bus distribution network. Design/methodology/approach The problem is studied in three scenarios, considering different obj...

Nowadays, more than a quarter of the faults that occur in oil-filled transformers are due to the aging and deterioration of their oil-paper insulation. Therefore, condition assessment of the oil-paper insulation of oil-filled transformers, which are installed in the power grids, is very important. One of the non-destructive methods, which are curre...

In this paper, designing a hybrid stand-alone photovoltaic/wind energy system with battery storage (PV/WT/Batt) is presented to minimize the total cost of the hybrid system and considering reliability constraints for Zanjan city in Iran country considering generation and load uncertainties. The total cost includes the cost of the system components...

For transformer designers, split-winding transformer modeling in different frequency ranges is of great importance. In this paper, for the first time, a multi-conductor transmission line model is proposed for high-frequency modeling of the split-winding transformer. In this model, all the turns in layers and disks have been considered and the model...

Obtaining the accurate fault location in the series compensated double-circuit transmission lines (SCDCTL) is a challenge due to the presence of series compensator, fault resistance, and mutual the coupling between parallel lines. Although by using the pilot fault location methods, the effect of all the aforementioned factors can be eliminated and...

The modeling of high frequency electromagnetic transients and the simulation of the voltage and the current distribution in the multi-winding traction transformer's windings are very important due to these transient waves. In the present article, in addition of presenting finite element models, the coupled field-circuit approach is proposed for the...

With the expansion of the use of frequency response analysis (FRA) as a reliable tool for fault detection in transformers, more capabilities of this method are discovered every day. So that today the number of transformer faults that can be identified by FRA method has also increased. One of the most critical steps in fault detection with FRA is to...

Short circuit fault occurrence in high-voltage DC (HVDC) systems causes extremely high currents in a fast raising time that does not experience current zero-crossing. To protect HVDC systems/grids against fault current, fast HVDC breaker is an essential equipment. This study presents the design procedure of a novel HVDC breaker based on solid-state...

Nowadays, more than a quarter of the faults that occur in oil-filled transformers are due to the aging and deterioration of their oil-paper insulation. Therefore, condition assessment of the oil-paper insulation of oil-filled transformers, which are installed in the power grids, is very important. One of the non-destructive methods, which are curre...

The fast raising nature of DC fault currents and sensitivity of high-voltage DC (HVDC) power converters to DC faults is critical protection issues. On the other hand, DC fault current does not meet zero; which causes DC to fault current breaking process become more challenging. Specifically, to protect HVDC grids against DC fault currents, the deve...

Energization of wind turbine transformers (WTTs) in wind power plants (WPPs) leads to high transient inrush current, which imposes high mechanical and thermal stresses on transformer windings and voltage sag problems at grid connection point (GCP). Therefore, to solve these problems, the inrush current should be suppressed during the energization t...

Frequency response analysis (FRA) is mainly used as a tool for detecting mechanical faults (especially displacement and deformation of windings and core) as well as electrical faults (especially short- circuits in windings) of transformers. In the FRA method, the transfer function (TF) of transformer is measured in a wide frequency range and these...

Locating a fault in double-circuit transmission lines is a challenging task due to the mutual coupling effects between adjacent circuits of the line. Also, performance of impedance-based fault location schemes for double-circuit lines is adversely affected by fault resistance. Accurate fault location in double-circuit lines can be achieved if fault...

Nowadays, one of the important methods for insulation condition assessment of oil transformer is Frequency Domain Spectroscopy (FDS) measurement. In recent years, a large number of researches finding reveal that the temperature variation affect FDS results. Master Curve technique is one of the commonly used techniques for correcting the effect of t...

High-frequency electromagnetic transients modelling of voltage and current distribution due to electromagnetic transients are of great importance in transformer design. In this study, a 2D and 3D finite-element, coupled field-circuit and modified detailed model is introduced for high-frequency electromagnetic transient studies in split-winding trac...

In this paper, the design of a hybrid renewable energy PV/wind/battery system is proposed for improving the load supply reliability over a study horizon considering the Net Present Cost (NPC) as the objective function to minimize. The NPC includes the costs related to the investment, replacement, operation, and maintenance of the hybrid system. The...

Today, most energy consumption in industry is related to induction motors. Evaluation of induction motor’s efficiency is an important issue for life estimation, extending the life and energy saving managements. Using the estimated efficiency of the induction motor, its performance can be judged and replacing the existing low efficiency motor by a h...

Due to the limitation of active power exchange between dynamic voltage restorers (DVRs) in an interline DVR (IDVR), selection of the appropriate voltage for each DVR in an IDVR is very important. In previous studies, an optimization problem by selecting the “minimization of the sum of rated apparent power of DVRs” as the objective function was prop...

In this paper, a new optimization method is proposed to solve the optimal sizing and siting problem of distributed generation (DG) in a distribution system (DS). The optimization problem is solved using a new ant lion optimizer (ALO) with considering different objectives. These objectives are reduction of purchased energy cost from upstream network...

Thermal modeling in the transient condition is very important for cast-resin dry-type transformers. In the present research, two novel dynamic thermal models have been introduced for the cast-resin dry-type transformer. These models are based on two artificial neural networks: the Elman recurrent networks (ELRN) and the nonlinear autoregressive mod...

In the recent years, cast-resin dry-type transformers (CRT) are considerably used in various areas of the electrical power industry. The major properties of these transformers include inflammability and moisture protection. This is the reason that they are an appropriate alternative for oil-immersed transformers in residential, hospitals, ships and...

In this research paper, a novel approach for dynamic thermal modeling of cast-resin transformer (CRT) is introduced. In order to analyze the dynamic behavior of the temperatures in this transformer, a new thermal model is introduced which is based on heuristic methods such as Particle Swarm Optimization (PSO) and an Improved Big Bang-Big Crunch (I-...

Nowadays, the most generated electrical energy is consumed by three-phase induction motors. Thus, in order to carry out preventive measurements and maintenances and eventually employing high-efficiency motors, the efficiency evaluation of induction motors is vital. In this paper, a novel and efficient method based on Improved Big Bang-Big Crunch (I...

In this paper a methodology of sizing optimization of a stand-alone hybrid PV/wind/battery power generation system (HPWGS) is proposed. The main objective of this optimization is to minimize the total annual cost (TAC) of the hybrid system considering power balanced constraint (PBC) and determination of the optimal number of wind turbines, PV panel...

In this paper, a methodology of sizing optimization of a stand-alone hybrid PV/wind/ battery power generation system (HPWGS) is proposed. The main objective of this optimization is to minimize the total annual cost (TAC) of the hybrid system considering power balanced constraint and determination of the optimal number of wind turbines, PV panels, a...

This paper proposes an effective method for very accurate parameter estimation of single- and double-diode solar cell models. For this purpose, unknown parameters of model are estimated by minimization of an objective function using a new highly effective modified version of artificial bee colony (ABC) algorithm. The proposed algorithm is used for...

Transformers are one of the most important components of the power system. It is important to maintain and assess the condition. Transformer lifetime depends on the life of its insulation and insulation life is also strongly influenced by moisture in the insulation. Due to importance of this issue, in this paper a new method is introduced for deter...

It is becoming increasingly difficult to ignore the role of the optimal design of the proportional-integral-derivative (PID) controller in achieving a satisfactory response in the automatic voltage regulator (AVR) system. The main aim of this paper is to determine the optimal gains of a PID controller in the AVR system using teaching-learning based...

To study the behavior of the transformers and the effects of these devices on power network performance in transient states, various models with different objectives are presented. One of the most important objectives is to investigate the overvoltages made in transformer as a result of lightning waves. For this reason, a black box model applied in...

The growing interest in sharing the renewable-energy resources in power microgrids presents major challenge from the perspective of reliable operation and control of the power systems. The issue of the microgrids autonomous control has received a considerable attention in the last decade. As the architecture of the power system control, a hierarchi...

Calculating leakage inductances between windings of traction transformer is one of the most important schemes in design procedure. In this paper, analytic, semi-analytic and finite element methods are introduced for electromagnetic modeling of different geometries of the traction transformer. Using these methods, the leakage inductances between win...

In this research paper, a novel approach for dynamic thermal modeling of cast-resin dry-type transformer is introduced. In order to analyze the dynamic behavior of the temperatures in this type of transformer, a new thermal model has been introduced which is based on particle swarm optimization (PSO) algorithm. Selecting a typical 400kVA dry-type t...

To study the behavior of the transformers and the effects of these devices on power network performance in transient states, various models with different objectives are presented. One of most important ob-jectives is to investigate the overvoltages made in transformer as a result of lightning waves. For this reason, a black box model applied in th...

Employing Resistive Superconducting Fault Current Limiters (RSFCL) is one of the practical and effective methods to improve the transient stability of a power system by limiting the fault current. Regarding technical and economical constraints, optimal sizing and allocation of RSFCLs in a power system is of significant importance. It is the purpose...

Power transformers are one of the most important and essential equipment in power plants, transmission lines and distribution networks which any damage or dysfunction directly leads to the reduction of network reliability and increase maintenance costs. With the modern restructured market, unplanned outage of any one of the power transformers can r...

In this paper a novel model for analyzing the transient state of the distribution transformers is proposed. The presented model is as simple that the simulation process can be conducted so fast and easy and also its application in the form of a two port element in power network is possible. By considering the complexity of the analytical methods, P...

Transformers winding axial displacement are considered one of the main causes of their failure. Nowadays, several methods have been developed to detect these faults in transformers. In some of these methods, transformers should be used off-line and another method can be implemented when the transformers are under load. Off-line methods reduce syste...

This paper presents a new method for determination the type of transformer winding fault through transfer function (TF) analysis. For this purpose, probabilistic neural network (PNN) is used. Outset of all, the required measurements are carried out on two groups of transformers, under both intact and faulted conditions of different degrees in axial...

This paper presents a new method for determination of the relative contribution of utility and customer in creation of voltage and current harmonic distortions in PCC (Point of Common Coupling) bus. In proposed method, accurate information of harmonic impedance of customers is not needed. At first, using superposition method and definition of harmo...

In this paper, a new method is introduced for identification of transformer winding fault through transfer function analysis. For this analysis, vector fitting and probabilistic neural network are used. The results of transfer functions estimation through vector fitting are employed for training of neural network, and consequently, probabilistic ne...

Since a few years ago, there is an increasing interest for utilization of transfer functions (TF) as a reliable method for diagnosing of mechanical faults in transformer structure. However, this paper aims to develop the application of TF method in order to evaluate the drying quality of active part during the manufacturing process of transformer....

To enhance the reliability of grids and also safety of power instruments, it is too important to distinguish their defects before a complete damage. Therefore insulation modeling of these instruments is noticed to recognize their insulation conditions and performance. In this paper, a simple RC model is used to model the power insulating instrument...

This study presents an intelligent fault classification method for identification of transformer winding fault through transfer function (TF) analysis. For this analysis support vector machine (SVM) is used. The required data for training and testing of SVM are obtained by measurement on two groups of transformers (one is a classic 20 kV transforme...

As it is found in the related published literatures, the transfer function (TF) evaluation method is the most feasible method for detection of winding mechanical faults in transformers. Therefore, investigation of an accurate method for evaluation of the TFs is very important. This paper presents three new indices to compare the transformer TFs and...

Calculating leakage inductances between windings of multi-winding Traction transformers is one of the most important schemes in design procedure. In this paper, analytical and finite element methods (FEM) have been introduced for electromagnetic modeling of traction transformers with four pancake split windings. Using these models, the leakage indu...

In this work, a new model of transformer winding is developed. The components in the model are determined by the geometric and electric data of the winding (detailed model) and using experimental data based on genetic algorithm. Under different degrees of axial displacement and radial deformation in the winding, the circuit parameters of the model...

Along with the rapid development of industrial systems, multi-winding transformers are widely used in electrical networks. Determination of current in the different loading regimes of the multi-winding traction transformer, specially during short circuit and start-up conditions, requires a low frequency model. In this paper a new low frequency mode...

Transfer function (TF) is an acknowledged method for power transformer winding faults detection. The important winding faults, which are most likely to be detected using the TF analysis, can be classified as follows: a-Axial Displacement (AD), b-Radial Deformation (RD), c-Disc Space Variation (DSV) and d-Short circuit (SC) The past published works...

Transfer function (TF) is an acknowledged method for power transformer mechanical faults detection. However the past published works mostly discovered how to specify the faults levels and paid less attention to detection of the type of faults using comparison of TFs. whereas, it seems important for most of the applications to specify the type of fa...

Calculating leakage inductances between windings of multi-winding Traction transformers is one of the most important schemes in design procedure. In this paper, analytical and finite element methods (FEM) have been introduced for electromagnetic modeling of traction transformers with four pancake split windings. Using these models, the leakage indu...

In this work, a new model of transformer winding is developed. The components in the model are determined by the geometric and electric data of the winding. Under different degrees of axial displacement and radial deformation in the winding, circuit parameters in the model will be changed and thus the character of the circuit will be influenced. Af...

Abstract It is the purpose of this paper to investigate the design of a stabilizer via sampling the speed and voltage feedback in order to improve the oscillations of generators in Siahbisheh pumped-storage power plant in Iran. An overall PSS is utilized for all of the generators and its output is connected separately to the generators excitation s...

In this paper, a black box model is proposed to analyze the transient state of distribution transformers. This model is capable of showing the frequency characteristics of the transformer under various conditions of the terminals connections up to the frequency domain of almost 1.2 MHz. In addition, this model has satisfactory abilities in illustra...

In this paper, a black box model has been proposed in order to analyze transformer transient behaviors. This model is capable to reveal the transformer impedance (or admittance) characteristics up to 1.2 MHz observed from transformer terminals under various connections. Also, this model is powerful to display the characteristic of traveling wave to...

In this paper, some models have been introduced for dynamic thermal modeling of cast-resin transformers which are based on genetic algorithm. A typical 400kVA cast-resin transformer has been selected and the model parameters are estimated and validated with the help of experimental data extracted from different load cycles. The estimated models are...

A proper model is proposed in this paper for transient analysis of distribution transformers. The model is capable of representing the impedance or admittance characteristics of the transformer measured from the terminals under different terminal connections up to approximately 200 kHz. The model is simple, so that the simulation with this model is...

Various models have been presented for evaluation and study of transformers, but a model including all the following properties has not been given in literature by now: (1) The parameters of the model can be calculated through geometrical dimensions, so investigation of a fault effect on the model is possible and it needs no costly measurements. (2...