다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

2 1 The innovative transport systems and the CityMobil project 10 1.1 The research questions 10 2 The state of art in the field of automatic transport systems 12 2.1 Case studies and demand studies for innovative transport systems 12 3 The design and implementation of surveys 14 3.1 Definition of experimental design 14 3.2 Questionnaire design and delivery 16 3.3 First analyses on the collected sample 18 4 Calibration of Logit Multionomial demand models 21 4.1 Methodology 21 4.2 Calibration of the “full” model. 22 4.3 Calibration of the “final” model 24 4.4 The demand analysis through the final Multinomial Logit model 25 5 The analysis of interaction between the demand and socioeconomic attributes 31 5.1 Methodology 31 5.2 Application of Mixed Logit models to the demand 31 5.3 Analysis of the interactions between demand and socioeconomic attributes through Mixed Logit models 32 5.4 Mixed Logit model and interaction between age and the demand for the CTS 38 5.5 Demand analysis with Mixed Logit model 39 6 Final analyses and conclusions 45 6.1 Comparison between the results of the analyses 45 6.2 Conclusions 48 6.3 Answers to the research questions and future developments 52

The European commission

Renewable energy sources like wind, sun, and hydro are seen as a reliable alternative to the traditional energy sources such as oil, natural gas, or coal. Distributed power generation systems (DPGSs) based on renewable energy sources experience a large development worldwide, with Germany, Denmark, Japan, and USA as leaders in the development in this field. Due to the increasing number of DPGSs connected to the utility network, new and stricter standards in respect to power quality, safe running, and islanding protection are issued. As a consequence, the control of distributed generation systems should be improved to meet the requirements for grid interconnection. This paper gives an overview of the structures for the DPGS based on fuel cell, photovoltaic, and wind turbines. In addition, control structures of the grid-side converter are presented, and the possibility of compensation for low-order harmonics is also discussed. Moreover, control strategies when running on grid faults are treated. This paper ends up with an overview of synchronization methods and a discussion about their importance in the control

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Overview of Control and Grid Synchronization for Distributed Power Generation Systems

DC and AC Microgrids are key elements to integrate renewable and distributed energy resources as well as distributed energy storage systems. In the last years, efforts toward the standardization of these Microgrids have been made. In this sense, this paper present the hierarchical control derived from ISA-95 and electrical dispatching standards to endow smartness and flexibility to microgrids. The hierarchical control proposed consist of three levels: i) the primary control is based on the droop method, including an output impedance virtual loop; ii) the secondary control allows restoring the deviations produced by the primary control; and iii) the tertiary control manage the power flow between the microgrid and the external electrical distribution system. Results from a hierarchical-controlled microgrid are provided to show the feasibility of the proposed approach.

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Hierarchical control of droop-controlled DC and AC microgrids — a general approach towards standardization

The use of distributed energy resources is increasingly being pursued as a supplement and an alternative to large conventional central power stations. The specification of a power-electronic interface is subject to requirements related not only to the renewable energy source itself but also to its effects on the power-system operation, especially where the intermittent energy source constitutes a significant part of the total system capacity. In this paper, new trends in power electronics for the integration of wind and photovoltaic (PV) power generators are presented. A review of the appropriate storage-system technology used for the integration of intermittent renewable energy sources is also introduced. Discussions about common and future trends in renewable energy systems based on reliability and maturity of each technology are presented

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Power-Electronic Systems for the Grid Integration of Renewable Energy Sources: A Survey

Nowadays, the design of power converters has been focused on the optimization in terms of reliability, fault-tolerant capability and power density. The use of modular converters leads to natural fault-tolerant capability because the power system can be still operating even when some module has failed. In this paper, the reliability of modular converters, which is high-dependent of several factors like as thermal stress, is studied. In the paper, the power devices aging of dc/dc interleaved power converters is managed. The proposed method is based on sharing conveniently the total managed power between the power modules. This can be done without losing performance in the power system. The proposed power routing technique has been tested in a three-module interleaved boost converter which is used in multiple applications.

Power Device Lifetime Extension of Dc-Dc Interleaved Converters via Power Routing

The ongoing electrification of the transport sector raises demands for new power electronic solutions. As a consequence, modular converter structures are state of the art for fast charging, since high power and short charging times are required. This work presents a modular multiport DC-DC converter which has the capability to decrease the cost and size of the required charging station. Furthermore, design guidelines for the investigated topology are presented. The analysis is validated with a three port isolated DC-DC converter with separated loads.

Isolated Multiport Converter as Cost Efficient Solution for DC-Fast Charger of Electric Vehicle

Distribution grids unbalance challenges the DC-link of the Smart Transformer leading to higher ripples and then the lifetime of the DC aluminium electrolytic capacitors (AEC) is reduced. Additionally, dead time and nonlinearity characteristic of IGBT also may introduce ripple current in DC link, potentially decreasing the lifetime of AEC. Based on physical characteristic of AEC, the lifetime estimation of AEC is investigated considering aforementioned impacts. To suppress these impacts, an improved voltage control strategy that can reduce AEC current ripple and then preserve AEC lifetime is proposed. The theoretical analysis has been demonstrated by the simulation results.

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Voltage control strategies of smart transformer considering DC capacitor lifetime

In this article, a voltage-fed isolated matrix-type ac/dc converter (VF-MC) is proposed for wind energy conversion system (WECS). Instead of the line-frequency transformer, the high-frequency transformer (HFT) is used for isolation between the generator and the grid. The direct matrix converter (MC) is employed to connect the wind power generator and the HFT, and the intermediate dc capacitors are saved in the ac/ac conversion. Moreover, the proposed VF-MC can work without use of filter capacitors on generator side, and enable more compact size. The dedicated space-vector-modulation scheme and commutation method are proposed for safe operation of the MC. The voltage spikes due to the leakage inductance of HFT are thus reduced and the additional snubber circuit is avoided in the proposed system. A 1-kW laboratory prototype of the proposed VF-MC-based WECS is built to verify the effectiveness of the system experimentally.

Voltage-Fed Isolated Matrix-Type AC/DC Converter for Wind Energy Conversion System

PV converters can be designed to improve grid power quality implementing power conditioning functionalities. This paper presents a single-phase photovoltaic system with power quality enhancement capability. It provides grid voltage support at fundamental frequency and compensation of harmonic distortion at the point of common coupling (PCC). The shunt-converter is voltage controlled by means of a repetitive controller which is able to compensate the selected harmonics. Experimental results confirms the validity of the proposed topology also in case of nonlinear loads.

Marco Liserre

Papers

Power Device Lifetime Extension of Dc-Dc Interleaved Converters via Power Routing

Isolated Multiport Converter as Cost Efficient Solution for DC-Fast Charger of Electric Vehicle

Voltage control strategies of smart transformer considering DC capacitor lifetime

Voltage-Fed Isolated Matrix-Type AC/DC Converter for Wind Energy Conversion System

PV system power quality enhancement by means of a voltage controlled shunt-converter