Query: Literature review transformers

Candidate papers:

abstract: With the global trend to produce clean electrical energy, the penetration of renewable energy sources in existing electricity infrastructure is expected to increase significantly within the next few years. The solid state transformer (SST) is expected to play an essential role in future smart grid topologies. Unlike traditional magnetic transformer, SST is flexible enough to be of modular construction, enabling bi directional power flow and can be employed for AC and DC grids. Moreover, SSTs can control the voltage level and modulate both active and reactive power at the point of common coupling without the need to external flexible AC transmission system device as per the current practice in conventional electricity grids. The rapid advancement in power semiconductors switching speed and power handling capacity will soon allow for the commercialisation of grid rated SSTs. This paper is aimed at introducing a state of the art review for SST proposed topologies, controllers, and applications. Additionally, strengths, weaknesses, opportunities, and threats (SWOT) analysis along with a brief review of market drivers for prospective commercialisation are elaborated.
author_names: Ahmed Abu-Siada

Jad Budiri

A F Abdou
title: Solid State Transformers Topologies, Controllers, and Applications: State of the Art Literature Review
year: 2018

abstract: The high voltage power transformer is the critical element of the power system, which requires continuous monitoring to prevent sudden catastrophic failures and to ensure an uninterrupted power supply. The most common failures in the transformer are due to partial discharge (PD) in electrical insulations which are the results of the insulation degradation over time. Different approaches have been proposed to monitor, detect, and locate the partial discharge in power transformers. This paper reviews and evaluates the current state of the art methods for PD detection and localization techniques, and methodologies in power transformers. Detailed comparisons of PD detection techniques have been identified and discussed in this paper. The drawbacks and challenges of different partial discharge measurement techniques have been elaborated. Finally, brief reviews of PD denoising signals, feature extraction of PD signals, and classification of partial discharge sources have been addressed.
author_names: Md Rashid Hussain

Shady S Refaat

Haitham Abu-Rub
title: Overview and Partial Discharge Analysis of Power Transformers: A Literature Review
venue: IEEE Access
year: 2021

abstract: Due to the large number of distribution transformers in the distribution grid, the status of distribution transformers plays an important role in ensuring the safe and reliable operation of the these grids. To evaluate the distribution transformer health, many assessment techniques have been studied and developed. These tools will support the transformer operators in predicting the status of the distribution transformer and responding effectively. This paper will review the literature in the area, analyze the latest techniques as well as highlight the advantages and disadvantages of current methodologies.
author_names: Q T T Tran

Kevin Davies

Leon R Roose

Puthawat Wiriyakitikun

Jaktupong Janjampop

Eleonora Riva Sanseverino

Gaetano Zizzo
title: A Review of Health Assessment Techniques for Distribution Transformers in Smart Distribution Grids
year: 2020

abstract: One of the most important innovation expectation in railway electrical equipment is the replacement of the on board transformer with a high power converter. Since the transformer operates at line frequency (i.e. 50 Hz or 16 2/3 Hz) it represents a critical component from weight point of view and, moreover, it is characterized by quite poor efficiency. High power converters for this application are characterized by a medium frequency inductive coupling and are commonly referred as Power Electronic Transformers (PET) Medium Frequency Topologies or Solid State Transformers (SST) Many studies were carried out and various prototypes were realized until now, however, the realization of such a system has some difficulties, mainly related to the high input voltage (i.e. 25 kV for 50 Hz lines and 15 kV for 16 2/3 Hz lines) and the limited performance of available power electronic switches. The aim of this study is to present a survey on the main solutions proposed in the technical literature and, analyzing pros and cons of these studies, to introduce new possible circuit topologies for this application.
author_names: Stefano Farnesi

Mario Marchesoni

Massimiliano Passalacqua

Luis Vaccaro
title: Solid State Transformers in Locomotives Fed through AC Lines: A Review and Future Developments
year: 2019

abstract: It is well known that transmission and distribution sections of a real world power system are physically coupled by distribution transformers. This implies that almost every large scale power system is an integrated Transmission Distribution (T D) system that consists of a Transmission Power Subsystem (TPS) and multiple Distribution Power Subsystems (DPSs) Therefore, technically, only by considering the TPS and the DPS as a whole, can people accurately assess the state of the entire power system and optimally control the system.
author_names: Zhengshuo Li
title: Backgrounds and Literature Review
year: 2018

abstract: This paper presents a literature review on magnetically controlled devices, variable inductors (VI) and variable transformers (VT) and their applications to lighting gears for discharge lamps and/or LED lamps. These current controlled devices are mainly characterized by nonlinear and non uniform saturation of the magnetic core. The paper describes the fundamentals and basic operating principle of such devices and provides an overview of existing patents. These patents refer the devices, VIs or VTs, as useful or industrially applicable. Some present one or more claims regarding the construction of the device and behavioral characteristic; others refer to specific applications, such as voltage regulation or universal ballast operation. Afterwards, the paper focuses on the review of specific techniques and circuits taking advantage of the presence of a controlled inductance value, by covering recent applications regarding discharge and solid state lamp drivers. These applications will show how these multi winding devices, typically not considered due to their low efficiency, may fulfill an important role and add features to state of the art lamp drivers.
author_names: Marina S Perdigao

Maikel Fernando Menke

Alysson Raniere Seidel

Rafael A Pinto

Jose Marcos Alonso Alvarez
title: A Review on Variable Inductors and Variable Transformers: Applications to Lighting Drivers
venue: IEEE Transactions on Industry Applications
year: 2016

abstract: Transformers have achieved great success in many artificial intelligence fields, such as natural language processing, computer vision, and audio processing. Therefore, it is natural to attract lots of interest from academic and industry researchers. Up to the present, a great variety of Transformer variants (a.k.a. X formers) have been proposed, however, a systematic and comprehensive literature review on these Transformer variants is still missing. In this survey, we provide a comprehensive review of various X formers. We first briefly introduce the vanilla Transformer and then propose a new taxonomy of X formers. Next, we introduce the various X formers from three perspectives: architectural modification, pre training, and applications. Finally, we outline some potential directions for future research.
author_names: Tianyang Lin

Yuxin Wang

Xipeng Qiu
title: A Survey of Transformers
venue: ArXiv
year: 2021

abstract: In data analysis, context information plays a significant role in enhancing the quality of the insight obtained. Furthermore, spatial analysis helps understand spatial relationships among entities. Nevertheless, findings of a comprehensive literature review show that the characterization of geographic areas based on user generated content, such as text messages, has not been sufficiently explored. This paper focuses on investigating how to combine and exploit geographic information with user generated text content to detect geographic clusters of textual events, and infer relationships between each cluster and a fixed set of retail product categories, which we consider as an insightful way to perform spatial market segmentation. We propose a workflow composed of several machine learning models incorporating Transformers as an attention mechanism and BERT based data augmentation capable of predicting product classes from Amazon product reviews and Twitter message corpora, and then characterizing the obtained geographic clusters based on their aggregated scores. The output of our system is an effective visualization of the geographic areas with their corresponding relevance score against a fixed set of categories. We trained a product document classifier achieving an F1 Score of 86% in the test set for product reviews, and of 76% in the test set for tweets; and validated our approach by manually annotating a subset of Twitter data with respect to ten product categories. Our approach provides practitioners with a mechanism to combine location context, a Transformer encoder, and transfer learning to derive insights from geo spatial and text data; and researchers with opportunities to continue advancing the field.
author_names: Luis E Ferro-Diez

Norha M Villegas

Javier Diaz-cely

Sebastian G Acosta
title: Geo Spatial Market Segmentation Characterization Exploiting User Generated Text Through Transformers Density Based Clustering
venue: IEEE Access
year: 2021

abstract: In this project dynamic thermal rating for transformers and its effect on transformer reliability are investigated. A literature review is done on different thermal models used for this purpose and
author_names: Tahere Zarei
title: Analysis of reliability improvements of transformers after application of dynamic rating
year: 2017

abstract: In multi phase power conversion circuits, achieving an equalized current sharing between the paralleled modules is a challenge. Especially, in the LLC resonant converter topology, where the voltage gain is very sensitive to a minor change in the resonant tank parameters. In practical applications, the resonant tank parameters are never exactly identical among the phases, leading to unbalanced current sharing between the paralleled modules. This paper reviews the state of the art of current balance mechanisms proposed previously in the literature and revisits a newly proposed method to improve the current balance, which relies on a single balancing transformer connected in series with the paralleled resonant tanks. A comparison between the proposed method and connecting the three transformers in star is conducted. While evaluating the current balancing methods, the following sources of unbalance have been considered: a) resonant and magnetizing inductances b) resonant capacitors. c) on resistances of the switching devices. d) propagation delay of the gate drivers.
author_names: Mostafa Noah

Jun Imaoka

Yuki Ishikura

Kazuhiro Umetani

Masayoshi Yamamoto
title: Review of Current Balance Mechanism in Multiphase LLC Resonant Converters
venue: 2018 IEEE 27th International Symposium on Industrial Electronics (ISIE)
year: 2018