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

A Performance Comparison of High-Efficiency Transformer-Less PV Inverters

Talkative power converter (TPC), which embeds signals into switching ripple, achieving the power line communication (PLC) and consequently enabling the power to communicate, has been proposed recently to significantly enhance the coordination control capability of power converter-interfaced resources. Since the talkative power (TP) is an emerging technique and a special PLC, a comprehensive overview of the advanced PLC techniques and the application scenarios of talkative-power-based PLC (TP-PLC) is missing in current literature. Hence, in this paper, a review of switching-ripple-based PLC (SR-PLC) techniques is detailed, to summarize their advances and performances in terms of the SR-PLC principles, SR-PLC in non-isolated converter and isolated converter, as well as the applications in visible light communication, battery management system, switching reluctance generator/motor and wireless electric vehicle charging stations. Finally, the trending topics of TP-PLC are discussed.

Review of Coding Theory and Applications of Switching Ripple-based Talkative Power Converters

With increased penetration of renewable energy sources in electric grid, maintaining quality voltage at the load terminal has become a challenge. Voltage disturbances like sag, swell, harmonics, etc., can propagate from one section to another section of electric grid and degrade the performance of sensitive loads. This paper explores the capability of smart transformer (ST) to improve the voltage quality in medium voltage (MV) grid, by replacing one conventional power transformer (CPT) with an ST in a multifeeder electric grid. In addition to supplying ST low voltage loads, the voltage regulation in MV grid is achieved by controlling the reactive current injection to the MV grid. Harmonic damping capability is integrated with the control loop to damp out the grid voltage harmonics. An improved stability of MV grid voltage regulation control is achieved in the presence of harmonic damping loop and this is verified with theoretical analysis. Extensive simulation study is carried out to validate the ST features.

Voltage quality improvement in smart transformer integrated distribution grid

In the field of heavy-duty electric vehicles and charging infrastructure, the energy sources are susceptible to transients with different amplitudes and dynamics. Energy storage systems (ESSs) must be designed by a trade-off between specific response time and energy density, because one single energy source is insufficient to supply such a high power system. Integrating ESSs with different capabilities, such as fuel-cell, battery, and supercapacitors, as a single energy source is required. In this context, a resonant multiwinding transformer-based (MTB) converter can be used to efficiently interconnect these different ESSs to the load, since the resonant converters are able to operate at a high switching frequency and hence enable high bandwidth control. However, due to the multiple resonant circuits and possible parameter deviations, the control capability might be compromised. Thus, a multiport resonant dc-dc converter embedded with variable inductors is proposed to enhance the power flow management among these different ESSs with reduced conversion stages. Further, the proposed concept can also improve the immunity to parameter deviations on the resonant by compensating the resonant frequency. Finally, simulations and experimental results of a 4-port resonant dc-dc converter embedded with variable inductors are presented to demonstrate the effectiveness of the proposed system.

Multiport Resonant DC-DC Converter using Actively-Controlled Inductors for Hybrid Energy Storage System Integration

Resonant controllers are widely used in applications like active power filters and identification systems, where control of harmonics of high order (high frequency) is required. In such high-frequency range, to compensate the PWM/computational phase delay is necessary to avoid instability. Two approaches have been proposed in literature: a 2-sample delay compensation and a linear phase-leading compensation. In this work, a stability analysis has been performed to prove that linear phase compensation can leads to low frequency instability if the selectivity and sampling frequency of the resonant controllers are not properly chosen. A zone-phase compensation is proposed to solve the instability and to maximize the stability margins in all the frequency operating range. The analysis is validated by extensive simulation and by field experiments in a 1.6 MVA 6-parallel three-phase NPC grid impedance analyzer.

Marco Liserre

Papers

A Performance Comparison of High-Efficiency Transformer-Less PV Inverters

Review of Coding Theory and Applications of Switching Ripple-based Talkative Power Converters

Voltage quality improvement in smart transformer integrated distribution grid

Multiport Resonant DC-DC Converter using Actively-Controlled Inductors for Hybrid Energy Storage System Integration

High-Frequency Harmonic Current Control of Power Converters