126 research outputs found
Design and Stability Analysis of a Three-Phase Triple-Stage Solid-State Transformer
No full textThe electrical distribution system is experiencing a profound evolution process triggered by the increasing integration of Renewable Energy Sources (RES) and Distributed Generation (DG), alongside the widespread use of Electric Vehicles (EVs), the related charging stations, and the growing adoption of Energy Storage Systems (ESSs). The behavior of such loads and sources, interfaced with the grid via an increasing number of power electronics converters and often intermittent in nature, together with a bidirectional power flow requirement, poses new challenges for the reliable and safe operation of the distribution system. In this context, the concept of Internet of Energy (IoE), or Energy Internet (EI), has emerged and is nowadays widely discussed in the literature as a new paradigm shift to address the growing demand for modernization of the current distribution network. The goal in the IoE scenario is reshaping the current distribution grid into an intelligent and flexible active network, both through a radical informatization process that involves the renewal of the grid communication infrastructure and the addition of distributed monitoring points and via the implementation of advanced energy management and control functionalities to enable the safe, robust, effective, and efficient integration of intermittent sources and loads.
At the core of this future smart grid scenario, the Solid-State Transformer (SST) is envisioned as the best candidate due to its flexibility and advanced control features. This is because the SST is a power electronic-based transformer capable of providing advanced services and grid-supporting features, besides galvanic isolation and voltage adaptation, through its control system, and therefore is intended for replacing conventional Line Frequency Transformers (LFTs) at strategic nodes of the grid. Moreover, the core isolation stage of the SST operates at high frequencies and, therefore, it enables volume and weight reduction of the whole system compared to traditional and bulky LFTs.
In the IoE scenario, the most suitable SST configuration is the triple-stage one, which consists of three conversion stages. Due to the large number of stages, the SST control is intrinsically complex. It has been shown in the literature how the coupling among controllers makes the design of the overall control system challenging and, additionally, multistage cascaded converters are significantly prone to instability due to interaction between converters. Moreover, even if the SST is stable as a standalone system, it may become unstable when connected to the grid because of dynamic interactions with other grid-connected converters, leading to the so-called harmonic instability phenomenon.
In this context, this thesis aims to explore the SST stability issue from both the DC-link and grid-connection perspectives. To do so, in the first part of this work, the SST suitable topologies and their conversion stages are reviewed. Once the SST architecture is selected, the main ratings and parameters are designed according to the presented IoE application requirements. An average model of the converter, that enables faster simulations and physical insights into the SST dynamics, is then derived. Through it, the small-signal model of the SST can be obtained. Based on that, the SST control system is presented and designed and the related impedance model is derived. The latter is selected as assessment tool to evaluate the DC-link and grid-connection stability of the SST under investigation. The results obtained provide support during the design phase of the SST and its control strategy, with the aim to achieve a stable grid-connected operating system.The electrical distribution system is experiencing a profound evolution process triggered by the increasing integration of Renewable Energy Sources (RES) and Distributed Generation (DG), alongside the widespread use of Electric Vehicles (EVs), the related charging stations, and the growing adoption of Energy Storage Systems (ESSs). The behavior of such loads and sources, interfaced with the grid via an increasing number of power electronics converters and often intermittent in nature, together with a bidirectional power flow requirement, poses new challenges for the reliable and safe operation of the distribution system. In this context, the concept of Internet of Energy (IoE), or Energy Internet (EI), has emerged and is nowadays widely discussed in the literature as a new paradigm shift to address the growing demand for modernization of the current distribution network. The goal in the IoE scenario is reshaping the current distribution grid into an intelligent and flexible active network, both through a radical informatization process that involves the renewal of the grid communication infrastructure and the addition of distributed monitoring points and via the implementation of advanced energy management and control functionalities to enable the safe, robust, effective, and efficient integration of intermittent sources and loads.
At the core of this future smart grid scenario, the Solid-State Transformer (SST) is envisioned as the best candidate due to its flexibility and advanced control features. This is because the SST is a power electronic-based transformer capable of providing advanced services and grid-supporting features, besides galvanic isolation and voltage adaptation, through its control system, and therefore is intended for replacing conventional Line Frequency Transformers (LFTs) at strategic nodes of the grid. Moreover, the core isolation stage of the SST operates at high frequencies and, therefore, it enables volume and weight reduction of the whole system compared to traditional and bulky LFTs.
In the IoE scenario, the most suitable SST configuration is the triple-stage one, which consists of three conversion stages. Due to the large number of stages, the SST control is intrinsically complex. It has been shown in the literature how the coupling among controllers makes the design of the overall control system challenging and, additionally, multistage cascaded converters are significantly prone to instability due to interaction between converters. Moreover, even if the SST is stable as a standalone system, it may become unstable when connected to the grid because of dynamic interactions with other grid-connected converters, leading to the so-called harmonic instability phenomenon.
In this context, this thesis aims to explore the SST stability issue from both the DC-link and grid-connection perspectives. To do so, in the first part of this work, the SST suitable topologies and their conversion stages are reviewed. Once the SST architecture is selected, the main ratings and parameters are designed according to the presented IoE application requirements. An average model of the converter, that enables faster simulations and physical insights into the SST dynamics, is then derived. Through it, the small-signal model of the SST can be obtained. Based on that, the SST control system is presented and designed and the related impedance model is derived. The latter is selected as assessment tool to evaluate the DC-link and grid-connection stability of the SST under investigation. The results obtained provide support during the design phase of the SST and its control strategy, with the aim to achieve a stable grid-connected operating system
Kalman filter estimation method for battery cell parameters in Reconfigurable Cascaded Multilevel Converter
No full textDirect AC charging of EV Reconfigurable Cascaded Multilevel Converter
No full textThis paper presents the Reconfigurable Cascaded Multilevel Converter (RCMC), employed for EV powertrain applications, in charging configuration. The converter is directly connected to an AC three-phase power system and the battery modules are charged by dynamically controlling the reconfigurable battery modules. The intrinsic structure of the converter gives the advantage to implement different charging algorithms, according to customizable requirements, without the need of extra middle power stages. Two charging methods are proposed and explained in detail: the first one prioritizes the SOC balancing between the battery modules, the second one the power losses reduction. Finally, a charging time estimation is computed for the RCMC and for a classic battery pack, assuming to increase their initial state of charge of 20%. The computation results show that the Reconfigurable Cascaded Multilevel Converter requires 40% less time than the battery pack
Samuele R. Bacchiocchi and Family
No full textSeventh-day Adventist author and theologian, Samuele R. Bacchiocchi and his wife and their children at a graduation ceremony at Pontifical University
Impact of the DC-DC Stage on Grid-Connection Stability in Solid-State Transformer
No full textThis paper addresses the impact of the dc-dc stage on the grid-connection stability of a three-phase Solid-State Transformer based on the Cascaded H-Bridge and Dual Active Bridge topologies. In particular, the analysis aimed to reveal and discuss the impact of the isolated bidirectional dc-dc stage on the input dq-frame impedance matrix properties in terms of its passivity. For this purpose, the d-axis input impedance has been mainly addressed in this work. Its low-frequency simplified expression has been derived, by means of which its real part and the negative-resistance region upper limit can be analytically deduced, enabling a passivity-oriented design procedure. It is demonstrated that the dc-dc converter lowers that limit thus enhancing the grid-connected Solid-State Transformer passivity. The analysis performed in this work can be applied to a generic ac-dc-dc topology
Negative Voltage Sequence Control for an Electric Arc Furnace Power Supply based on a Multilevel AC-AC Converter
No full textThis paper proposes a novel control approach for a back to back multilevel AC-AC converter in Electric Arc Furnace (EAF) power supply applications. The study presents a feasibility analysis about the use of the chosen converter structure for EAF applications, along with considerations for control mechanisms. In particular, the effect of both positive and negative voltage sequences on the system is explored. Through comprehensive analysis, the paper introduces a novel control method utilizing negative voltage sequence, aiming to enhance the overall system performances. The results are presented using both a simplified model and the Cassie-Mayr (CM) model for the EAF
sd920/FIJI-macros-for-IHC-and-SHG-analysis: Batch Split Channels (3 channels)
No full textThis macro allows to split channels for Z-stack .tiff files and save them in a new folder in batch mode.
Author: Samuele Di Carmine, [email protected]
Version 1.0
July 13, 2021
//License: BSD3
Copyright 2021 Samuele Di Carmine, Imperial College Londo
Power Electronics Converters for the Internet of Energy: A Review
No full textThis paper presents a comprehensive review of multi-port power electronics converters used for application in AC, DC, or hybrid distribution systems in an Internet of Energy scenario. In particular, multi-port solid-state transformer (SST) topologies have been addressed and classified according to their isolation capabilities and their conversion stages configurations. Non-conventional configurations have been considered. A comparison of the most relevant features and design specifications between popular topologies has been provided through a comprehensive and effective table. Potential benefits of SSTs in distribution applications have been highlighted even with reference to a network active nodes usage. This review also highlights standards and technical regulations in force for connecting SSTs to the electrical distribution system. Finally, two case studies of multi-port topologies have been presented and discussed. The first one is an isolated multi-port bidirectional dual active bridge DC-DC converter useful in fast-charging applications. The second case of study deals with a three-port AC-AC multi-level power converter in H-Bridge configuration able to replicate a network active node and capable of routing and controlling energy under different operating conditions
Samuele R. Bacchiocchi
No full textSamuele R. Bacchiocchi was a Seventh-day Adventist author and theologian best known for his work on the Sabbath in Christianity, particularly in the historical work "From Sabbath to Sunday," based on his doctoral thesis from the Pontifical Gregorian University. Bacchiocchi defended the validity of the Feasts of the Lord, situated in Leviticus 23. He wrote two books on the subject. He was also known within the Seventh-day Adventist church for his opposition to rock and contemporary Christian music, jewelry, the celebration of Christmas and Easter, certain dress standards, and alcohol. This photograph was taken during a graduation ceremony from Pontifical University
The Impact of the COVID-19 Emergency on Local Vehicular Traffic and Its Consequences for the Environment: The Case of the City of Reggio Emilia (Italy)
No full textfirst_pagesettings
Open AccessArticle
The Impact of the COVID-19 Emergency on Local Vehicular Traffic and Its Consequences for the Environment: The Case of the City of Reggio Emilia (Italy)
by Samuele Marinello 1,*OrcID,Francesco Lolli 1,2 andRita Gamberini 1,2OrcID
1
En&Tech Interdepartmental Center, University of Modena and Reggio Emilia, 42124 Reggio Emilia, Italy
2
Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, 42122 Reggio Emilia, Italy
*
Author to whom correspondence should be addressed.
Sustainability 2021, 13(1), 118; https://doi.org/10.3390/su13010118
Received: 3 December 2020 / Revised: 21 December 2020 / Accepted: 22 December 2020 / Published: 24 December 2020
(This article belongs to the Special Issue 8th World Sustainability Forum—Selected Papers)
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Abstract
The COVID-19 health emergency has imposed the need to limit and/or stop non-essential economic and commercial activities and movement of people. The objective of this work is to report an assessment of the change in vehicle flows and in air quality of a specific study area in the north of Italy, comparing the periods February–May 2020 and February–May 2019. Circulating vehicles have been measured at nine characteristic points of the local road network of the city of Reggio Emilia (Italy), while atmospheric pollutant concentrations have been analysed using data extracted from the regional air quality monitoring network. The results highlight a rapid decline in the number of vehicles circulating in 2020 (with values of up to −82%). This has contributed to a reduction in air concentrations of pollutants, in particular for NO2 and CO (over 30% and over 22%, respectively). On the other hand, O3 has increased (by about +13%), but this is expected. Finally, the particulate matter grew (about 30%), with a behaviour similar to the whole regional territory. The empirical findings of this study provide some indications and useful information to assist in understanding the effects of traffic blocking in urban areas on air quality
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