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.

/pdf/hierarchical-control-of-droop-controlled-dc-and-ac-26q2w9lpco.pdf

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

The high implementation of renewable energy systems (RESs) and the need to increase transmission capacity across Europe (e.g., north-south Germany) have resulted in integrated power electronics (PE)-based solutions in electrical grids. PE allows more flexibility and control over power grids. Solutions such as high-voltage (HV) dc systems and flexible alternating current transmission systems (FACTS) increase energy transfer capabilities while preserving the system's safety (e.g., providing reactive power). Additionally, PE-based solutions, which are characterized by fast dynamic control actions, can support the grid during disturbances [e.g., a low-voltage ridethrough (LVRT) during faults]. These solutions are widely integrated into RES applications, where they enable maximized energy extraction from natural resources (e.g., the maximum power point tracker).

Which Deepness Class Is Suited for Modeling Power Electronics?: A Guide for Choosing the Right Model for Grid-Integration Studies

The paper presents a new current control scheme of a PWM shunt active filter with fuzzy logic estimation of the power devices duty cycles. The innovative control drives the inverter so the feedback current follows the real one without delay as a deep simulation campaign highlights. The effectiveness of such control has been tested when the distorting load is represented by both a variable speed induction motor drive and a fully controlled AC/DC power converter. The fuzzy control proposed shows a very high reduction of the line current harmonic distortion using a medium filter switching frequency.

A new fuzzy logic strategy for active power filter

Transformer-less photovoltaic (PV) inverters specifically designed to achieve high efficiency shall also comply with leakage current limits, low current harmonic distortion and reactive power handling capability. This paper aims at benchmarking some recently published or patented topologies with the most successful industrial products and it offers a complete trends scenario and a critical comparison. The performances are evaluated in terms of efficiency, common-mode voltage, leakage current, power quality, reactive power handling capability, size of the grid filter and power converter rating.

Transformer-less photovoltaic (PV) inverters: A critical comparison

4. Grid Synchronization in Single-Phase Power Converters

This paper deals with independent control and synchronization for three phase grid connected converters. Two different implementations of phase-locked loop (PLL), i.e. the conventional three phase PLL denoted here as dqPLL and the single phase PLL are discussed. The difference between these two algorithms and their influence on the current reference are highlighted. Additionally, the implementation of two linear controllers, namely proportional-integral (PI) and proportional-resonant (PR) in order to obtain independent control is also discussed. Equations of the controllers in both cases are derived. Finally, simulation results are presented in each case

Marco Liserre

Papers

Which Deepness Class Is Suited for Modeling Power Electronics?: A Guide for Choosing the Right Model for Grid-Integration Studies

A new fuzzy logic strategy for active power filter

Transformer-less photovoltaic (PV) inverters: A critical comparison

4. Grid Synchronization in Single-Phase Power Converters

Independent synchronization and control of three phase grid converters