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

/pdf/overview-of-control-and-grid-synchronization-for-distributed-2nx31ovpe9.pdf

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

/pdf/power-electronic-systems-for-the-grid-integration-of-4s5cxjhatl.pdf

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

Better quality of the input currents, unity power factor and regenerative capability are not the only benefits of equipping an adjustable speed drive (ASD) with an active front-end stage. Controlling the power inflow may enable also the reduction of the de-link energy storage, which will then lead to the replacement of the electrolytic capacitors with film capacitors, which have lower energy density meaning that the volume is similar, but increases the ASD lifetime. In these circumstances, operation under unbalanced and distorted supply voltage as well as high dynamic operation of the ASD makes the control task more challenging. The aim of this paper is to investigate the ride-through capability of an ASD with active front-end under real grid conditions and In view of the minimum de-link storage. Experiments validate the theoretical analysis.

Evaluation of the ride-through capability of an active-front-end adjustable speed drive under real grid conditions

Temperature sensitive electrical parameters allow junction temperature measurements on power semiconductors without modification to module packaging. The peak gate current has recently been proposed for IGBT junction temperature measurement and relies on the temperature dependent resistance of the internal gate resistor. In this paper, infra-red measurements are used to evaluate the validity of this method. Temperature measurements are made on IGBTs operating under steady state power dissipation. The peak gate current is found to provide a temperature slightly overestimating the temperature of the gate pad. Consequently, a consideration of chip geometry and location of the gate pad is required before interpreting temperature data from this method. Results are also compared with a traditional electrical temperature measurement method: the voltage drop under low current.

Experimental evaluation of IGBT junction temperature measurement via peak gate current

DC Microgrids have recently received a lot of attention in the last years due to high penetration of renewable energy sources as well as distributed energy storage systems. In the future DC microgrids could be preferable respect to AC microgrids in terms of redundancy since multi-DC-Bus solutions could provide a continuative power supply to the loads. An overview of Multi-DC-Bus solutions is presented in this paper. The performances are compared on the basis of possible DC microgrid configurations, redundancy, different DC voltage levels.

Overview of multi-DC-bus solutions for DC microgrids

Renewables will be the main sources for supplying energy (electric, thermal and gas) to end consumers. The European Union target is to cover about 80% of the energy loads by 2050. However, more flexibility options are needed to integrate such a huge amount of volatile energy sources into energy systems (electric, thermal and gas). Energy storage systems and multi energy systems are the best options. Industrial manufacturing systems also hide a large potential of flexibility options which could be offered to the system operators or be used within the manufacturing system to integrate the power generated by renewables into the manufacturing processes. The aim of this study is to identify and define the flexibility options that industrial microgrids might use to integrate volatile energy sources into the manufacturing process. The study analyzes the industrial microgrid from the point of view of a “net zero energy factory” and focuses mostly on the contribution that energy storage systems, production buffer stocks and smart transformers might provide to increase the flexibility options.

Flexibility options identification within Net Zero Energy Factories

The future electric grid concept will cover some small parts to be disconnected and work in an autonomous way isolated from the main utility. Control of microgrids — composed by the couple distributed sources-local loads — with the competence of operating in grid-connected and island mode is a trending research area. The presence of an efficient algorithm for synchronizing the microgrid with the main grid every time the reclosure is allowed is crucial for assuring a safe operation. The synchronization system presented in this work is compounded by two elements: Dual Second Order Generalized Integrator (DSOGI) and stationary reference frames phase-locked loop (SRF-PLL). Besides, the voltage control of the microgrid plays a great role in the synchronization system performance.

Marco Liserre

Papers

Evaluation of the ride-through capability of an active-front-end adjustable speed drive under real grid conditions

Experimental evaluation of IGBT junction temperature measurement via peak gate current

Overview of multi-DC-bus solutions for DC microgrids

Flexibility options identification within Net Zero Energy Factories

A synchronization technique for microgrid reclosing after islanding operation