Gevork B. Gharehpetian

Amirkabir University of Technology | TUS · Department of Electrical Engineering

This paper proposes multi-objective optimization framework to enhance the performance of demand response programs in distribution networks. The demand response programs are one of the main resources to enhance the flexibility of the energy systems to manage the uncertain behavior of renewable generation and demand loads. But, the uncoordinated resp...

IEEE Best Thesis Award: Selected as the best M.Sc Thesis for "Using ANN to Detect Mechanical Faults of Power Transformer Windings based on FRA Measurements," from IEEE Iran Section, Dec 28, 2022, Tehran, Iran.

In this paper, a new simple pulse multiplication circuit (SPMC) with low current stress is proposed, in order to upgrade a normal 20-pulse autotransformer rectifier (20PAR) to a 40PAR. The proposed SPMC comprises two tapped inter-phase reactors (TIPRs) and two additional diodes with lower conduction losses. The proposed SPMC does not require a zero...

Online monitoring of electric power components in smart grids is of great importance to enhance reliability. Fault detection at primary levels in distribution transformers, the chief components to maintaining the integrity of modern power networks, prevents following significant destructive damages and high costs of failures in smart grids. Data-dr...

Deriving benefits from a variety of flexible sources to lower or even eliminate renewable energy resources challenges is an imperative issue in the management of power systems. Constructing a well compatible flexibility evaluation method that encompasses cost minimization and flexibility improvement is crucial to tackle this. In this paper, a stoch...

Monitoring centers in the smart grid exchange the collected data by sensors and smart meters to monitor the current conditions and performance of electric power components. Distribution Power Transformers (DPTs) have a key role in maintaining the integrity of power flow in the smart grid. Online monitoring of DPTs to detect possible faults can pote...

Transformers are prominent elements of an electrical grid in which continuous service is of great importance, and high reliability of the entire network depends on health condition of the transformers. Transformer windings are susceptible to mechanical tensions as a result of poor operation or transit. Radial deformation (RD) as a mechanical windin...

A novel 40‐pulse autotransformer rectifier is proposed to reduce total harmonic distortion (THD) of the input current in aircraft electrical power systems. The 40‐pulse rectifier (40PR) includes a passive harmonic reduction circuit (PHMC) with a low kVA rating (about 0.95% of the load power) to enhance the performance of the conventional 40PR. This...

An islanded microgrid (MG) including low-inertia converter-based distributed generations (DGs) is subjected to instability. The virtual inertia concept was proposed to alleviate the stability issues by imitating the synchronous generators behavior. This paper spotlights on the optimization of virtual synchronous generator (VSG) parameters and virtu...

The differential protection of transformers sometimes does not have reliable performance facing some faults and events such as saturation of current transformers (CTs) during internal and external faults, inrush currents, and cross‐country faults (CCFs). In this paper, a new transformer differential protection scheme based on the self‐adaptive bias...

One of the important approaches in demand-side management is shifting energy usage from on-peak time to the other periods considering the financial conditions, which is known as a demand response program. To reduce the environmental concerns, energy policymakers have proposed to use renewable energy resources as clean energy and alternative source...

Due to the growing concerns regarding environmental and economic issues in power systems, nowadays the application of renewable energy sources (RES), especially wind energy has been increased. However, the increasing penetration of wind power plants (WPPs) into the grid has raised numerous challenges including output power fluctuations as well as t...

The two-way communication of electricity and information in smart homes facilitates the optimal management of devices with the ability to charge and discharge, such as electric vehicles and electrical storage systems. These devices can be scheduled considering domestic renewable energy units, the energy consumption of householders, the electricity...

This study provides an innovative solution by including sound levels in the energy management of light-emitting diodes (LEDs). At the same time, this method increases the accuracy of individuals' decisions regarding the environmental parameters of light and sound. The introduced system determines the environment's activity level using sound sensors...

In this paper, the Unified Interphase Power Controller (UIPC) is utilized to protect the synchronous generator in case of faults occurring in the transmission system. The UIPC not only maintains the generator’s stability by keeping its load angle within safe operational limits but also prevents high-amplitude currents from flowing through the stato...

This paper presents pulse multiplication technology based on an optimal Pulse Doubling Technique (PDT) to upgrade a 28-Pulse Rectifier (28-PR) to a 56-PR. The optimal PDT comprises a Tapped Interphase Reactor (TIPR) with a low kVA-rating and two diodes. The number of pulses can be increased from 28 to 56 using the PDT so that the input current harm...

Power transformers are vital components in a power system. One of the most effective and widely accepted ways in identifying mechanical defects of power transformer windings is frequency response analysis (FRA). In this paper, Disk space variations (DSVs), common transformer winding faults, are applied to the 20 kV windings of a 1.6 MVA distributio...

This paper presents a distributed fault-tolerant finite-time control algorithm for the secondary voltage and frequency restoration of islanded inverter-based Alternating Current (AC) Microgrids (MGs) considering input saturation and faults. Most existing distributed methods commonly design the secondary control layer based on ideal conditions of th...

Increasing short-circuit fault currents is one of the critical challenges in microgrids (MGs). In this paper, a novel AC/DC fault current limiter (ADFCL) is proposed to limit short circuit current of both DC and AC sides in hybrid AC/DC MGs (ADMGs). It includes two AC and DC ports, installed between AC MG (ACMG) and DC MG (DCMG). Also, it has only...

After the advent of restructured power systems and the transition from traditional grid management into deregulated management, which procures higher levels of intelligence, observability, agility, controllability, the importance of quantitative risk assessment and risk mitigation has been grown. In recent years, many market players have experience...

Distribution transformers are of great importance in power systems regarding electrical power supply to the consumers. To have a reliable and continuous service, monitoring of transformers is a crucial issue. Maloperation or improper transportation can result in mechanical tension and stress on transformer windings. Axial displacement (AD) is one o...

Here, the DC side passive harmonic reduction circuits (PHRCs) are compared from a technical and economic point of view. In researches on multipulse rectifiers (MPRs), the comparison is mainly based on different source and load conditions, especially accurate information on the amount of the source impedance is not available, which has a considerabl...

The cover image is based on the Original Research Paper Suggestion of DC side passive harmonic reduction circuits for industrial applications based on a comparative study by Rohollah Abdollahi and Gevork B. Gharehpetian https://doi.org/10.1049/pel2.12247. image

In this paper, a precious analysis is dedicated to thermal properties of three metal oxide-based nanofluid samples as well as their overall effects on a 630 kVA oil natural-air natural three-phase transformer thermal performance. The studied nanofluids comprise a typical mineral oil as the transformer base fluid in which Magnetite, Copper Oxide and...

The increase of Photovoltaics (PV) units’ penetration factor in the power grids might create overvoltage over the network buses. The active power curtailment (APC) and the reactive power provision methods use inverters to regulate their output active and reactive powers for high PV-penetrated grids. However, the mentioned solutions would reduce the...

With the growing need for energy, the concept of Microgrids (MG) with notable benefits for both production and demand sides was introduced. An MG consists of distributed generation units (DG), Energy Storage Systems (ESSs), and loads. It can operate either connected to the grid or in islanded mode. In the case of a fault or a disturbance, MG can be...

Certificate of top cited paper

Inherent nonlinearities and uncertainties are inseparable parts of real-life engineering systems, which make theoretical analyzes and control system designs more challenging. Usually, most of the physical parts in control systems such as controllers and actuators are subjected to saturation. On the other hand, uncertainties are ubiquitous in the ph...

The interconnection of AC and DC microgrids results in a hybrid AC/DC microgrid (HMG). In light of HMGs, the future smart grid implementation will be facilitated. One important aspect in HMGs is the interconnection of AC and DC microgrids and control of bidirectional interlink power converters (BILPCs), which has taken a lot of research attention i...

Today, despite the advances made, differential relays still fail to identify cross-country faults and some events. Therefore, in this paper, signal processing techniques and artificial intelligence were used to identify and classify cross-country faults with other events in transformers simultaneously. For this purpose, first, mechanical defects of...

Preventing the explosion of mixtures of combustible gases and vapors is an important task in industry. This research presents an approach for rapid assessment of the explosiveness of combustible gas mixtures of unknown composition. The technique is based on registering the amount of heat released during the combustion of a portion of gases inside t...

With the increase in the use of hybrid and renewable energy sources within the scope of measures taken to reduce greenhouse gas emissions, the difficulties brought by daily and seasonal changes in transmission and distribution need to be tackled. Energy storage systems (ESS) are essential technologies because of the support they provide in times of...

The Frequency Response Analysis (FRA) technique has advantages in identifying faults related to power transformers, but it suffers from the interpretation of frequency responses. This paper presents an approach based on statistical indices and Artificial Neural Network (ANN) methods to interpret frequency responses. The proposed procedure divides f...

The current interpretation procedure for the transformer frequency response analysis (FRA) is practically based on either subjective visual inspection or an observed value of a statistical indicator (SIn) programed in commercial software. However, both solutions are unable to provide very detailed information on transformer conditions in the indust...

This chapter presents decentralized power exchange control among AC and DC subsystems in future power networks. First, various methods to intertie several subsystems are investigated comprehensively. Various linkage methods are compared according to their merits and problems/difficulties in interconnected subsystems. It is shown that bidirectional...

This article proposes a novel control for the multiple-input, single-inductor, multiple-output dc–dc converters. It is digitally and discretely implemented, which can have an outstanding performance in low-power applications so that at the power of 10 mW, it has an efficiency of 92.5%. Conventionally, in this power range, an attempt is made to take...

IEEE Best Thesis Award: Selected as the best M.Sc Thesis for "Robust Cooperative Control of Active Distribution Networks Considering Uncertainties and PHEV", from IEEE Iran Section, Dec 09, 2021, Tehran, Iran.

Nowadays, the problem of the proper charging of PHEVs has become increasingly difficult because there is high uncertainty on both the demand and supply sides of MG systems, which may reduce efficiency and increase the cost of MG systems. Available solutions to these challenges are the application of energy storage systems and energy exchange with t...

Data analysis is becoming increasingly important in modern industrial systems. Widespread use of sensors and smart meters has introduced an information layer to the electricity distribution network for data collection, storage, and analysis. Distribution power transformers have a crucial role in smart data-driven power networks, so diagnosing the f...

This paper proposes a fault-tolerant control and a robust, distributed, simultaneous, passive fault detection and isolation (or FDI) for islanded ac microgrids (MGs), including heterogeneous distributed generations and battery energy storage systems (BESSs). Disturbances and both actuator and sensor faults are considered in this paper to design a r...

This study aims to use frequency response analysis, a powerful tool to detect the location and types of transformer winding faults. Proposing an effective intelligent approach for interpreting the frequency responses is the most crucial problem of this method and has created many challenges. Heat maps based on appropriate statistical indices have b...

Integration of multiple energy systems and the presence of smart energy hubs have provided increased flexibility and improved efficiency for the system. In this article, a bi-level decomposition approach (BLDA) is presented for coplanning of electricity and gas networks as well as the energy hub in distribution networks. The proposed multistage pla...

In Generation Expansion Planning (GEP), the power plants lifetime is one of the most important factors which to the best knowledge of the authors, has not been investigated in the literature. In this article, the power plants lifetime effect on GEP is investigated. In addition, the deep learning-based approaches are widely used for time series fore...

A cross-country fault is a fault occurring at two different locations of the same circuit, simultaneously or with a short time delay and possibly involving different phases,which is a challenge for the protection system. On the other hand, one of the main problems in transformer’s differential protection is distinction between inrush current and ot...

Among various storage technologies used for the energy storage systems, the supercapacitors, the Pb-acid Batteries (PABs) and the lithium Batteries (LBs) are widely used for microgrid applications. The supercapacitors with high-power density are suitable for fast power regulations; conversely, the PABs have high-energy density, which makes them sui...

The purpose of this paper is to optimally and economically schedule residential building energy system, considering renewable energy resources uncertainties and battery energy storage system (BESS) application under different operation modes. The power exchange of this system with the grid, named as building to grid (B2G) or grid to building (G2B)...

The islanding operation of hybrid microgrids (HmGs), which adopt the unified interphase power controller (UIPC) as the major element for interconnecting of AC and DC subsystems, is analyzed in this work. The studied HmG includes two AC subsystems and one energy storage-based DC subsystem (ESDC) and some flexible loads. A model reference adaptive co...

Frequency Response Analysis (FRA) is almost certainly the most efficient and well-established method for evaluating the mechanical integrity of transformer active part. FRA has a solid background in both industrial practice and academic research. Besides conventional visual analysis, a statistical analysis has been applied to the FRA data interpret...

The connection of large industrial microgrids to three-terminal transmission lines greatly complicates the protection scheme of the lines due to the uncertainty in generating renewable energy sources, the probability of unintentional islanding, the abrupt switching of sensitive and critical loads, the influence of supply and demand management progr...

In this paper, a new control method is proposed for microgrid-connected voltage source converters (VSCs), which generally contain voltage and current control loops. The voltage of the point of common coupling (PCC) is analyzed by recursive least squares (RLS) algorithm and its fundamental positive symmetric components are extracted by the voltage c...

Frequency response analysis is one of the best methods to diagnose mechanical defects in the power transformer winding. In this paper, sensitivity analysis of four components of the transfer function (TF), i.e., amplitude, phase, real and imaginary components of TF is investigated for different defects. The classification of type, location, and ext...