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 modular smart transformer (ST) is composed by several basic converters rated for lower voltage and power. In this paper, the quadruple active bridge (QAB) is used as the basic block for the modular ST. In this application, the efficiency and cost are the most important design parameters. Therefore, the paper focus on the design of the converter, with the aim to optimize its efficiency, taking the cost into consideration. To do so, the losses of all components are carefully modeled and a computer-aided design is used, where an algorithm to calculate the losses and cost is developed, allowing to perform multiobjective optimization. Additionally, silicon IGBTs and silicon carbide mosfet s are considered for the design and the performance of the converter using both semiconductors technology is compared. Experimental results obtained for the optimized 20 kW QAB converter has shown an efficiency of 97.5%.

/pdf/optimum-design-of-a-multiple-active-bridge-dc-dc-converter-2xbtycf1to.pdf

Optimum Design of a Multiple-Active-Bridge DC–DC Converter for Smart Transformer

Large renewable energy systems, e.g., photovoltaic and wind turbine, are connected to grid, which is usually weak, with long lines. This degrades power system stability and reliability. Additionally, the magnetic characteristic of a conventional power transformer (CPT) implies a slow dynamic and leads to grid current harmonic too high when wind speed is low and irradiance is weak. This paper proposes a parallel connection of a solid-state transformer-based smart transformer and a CPT to not only reduce the power rating, but also to support the voltage amplitude and improve the grid current quality. The simulation and experimental results clearly verify the correctness and feasibility of the proposed strategy.

/pdf/integration-of-large-photovoltaic-and-wind-system-by-means-4idz6mfvko.pdf

Integration of Large Photovoltaic and Wind System by Means of Smart Transformer

https://macau.uni-kiel.de/servlets/MCRFileNodeServlet/macau_derivate_00000459/impact_active_thermal_manage_power_electro_design.pdf

Impact of active thermal management on power electronics design

This paper presents a modified two-level three-phase inverter for the reduction of the leakage current. With respect to a traditional two-level inverter, the proposed solution reduces the common-mode voltage (CMV), both in amplitude and frequency. Between the dc source and the traditional three-phase bridge, two active dc-decoupling devices and a voltage-clamping network have been added. A dedicated control strategy was developed adopting a modified space vector pulse-width modulation, oriented to the reduction of the CMV. Simulations showing the good performance of the solution are presented. A preliminary prototype was developed and experimental results are presented.

/pdf/h8-inverter-for-common-mode-voltage-reduction-in-electric-4uxt312akm.pdf

H8 Inverter for Common-Mode Voltage Reduction in Electric Drives

Synchronverters have gained interest due to their capability of emulating synchronous machines, offering self-synchronization to the grid. Despite the simplicity of the control structure, the adoption of an LCL filter makes the overall model complex again, posing questions regarding the tuning of the synchronverter and its robustness. The multi-inputs multi-outputs (MIMO) formulation of the problem requires multivariable analysis. In this paper, the effects of control parameter and grid conditions on the stability of the system are investigated by means of structured singular values (or $\mu$ -analysis). A step-by-step design procedure for the control is introduced based on a linearized small-signal model of the system. Then, the design repercussions on the stability performance are evaluated through the performed robustness analysis. The developed linearized model is validated against time-domain simulations and laboratory experiments. These have been carried out using a power hardware-in-the-loop test bench, which allows as to test the synchronverter under different grid conditions. As a conclusion, this paper offers a simple guide to tune synchronverters but also a theoretical solid framework to assess the robustness of the adopted design.

/pdf/robust-stability-analysis-of-lcl-filter-based-synchronverter-1m49cqj71c.pdf

Marco Liserre

Papers

Optimum Design of a Multiple-Active-Bridge DC–DC Converter for Smart Transformer

Integration of Large Photovoltaic and Wind System by Means of Smart Transformer

Impact of active thermal management on power electronics design

H8 Inverter for Common-Mode Voltage Reduction in Electric Drives

Robust Stability Analysis of LCL Filter Based Synchronverter Under Different Grid Conditions