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

This paper presents a literature review of the recent developments and trends pertaining to Grid-Connected Photovoltaic Systems (GCPVS). In countries with high penetration of Distributed Generation (DG) resources, GCPVS have been shown to cause inadvertent stress on the electrical grid. A review of the existing and future standards that addresses the technical challenges associated with the growing number of GCPVS is presented. Maximum Power Point Tracking (MPPT), Solar Tracking (ST) and the use of transformless inverters can all lead to high efficiency gains of Photovoltaic (PV) systems while ensuring minimal interference with the grid. Inverters that support ancillary services like reactive power control, frequency regulation and energy storage are critical for mitigating the challenges caused by the growing adoption of GCPVS.

Trends and Challenges of Grid-Connected Photovoltaic Systems – A Review

Smart grid engineering is the key for a beneficial use of widespread energy resources, it is a modernized electrical grid that uses analog or digital information and communications technology. Renewable energy itself a thrust area of research due to its availability, applicability and environmental friendly nature and the application of smart grid in renewable energy makes it vast and more promising. This fusion enables the efficient use of renewable energies which is a key challenge for now. The present review paper attempts to investigate the role of smart grid in the renewable energy. The introductory section sets the role of renewable energy and distributed power in a smart grid system. Subsections cover the concept and availability of renewable energies, renewable energy power calculation formulae, smart grid concepts and its feasibility, case studied as performed by different researchers around the World, discussion and future recommendations and finally the conclusions from the study. To achieve this, articles from different sources such as internet, reports, conferences and journals of Elsevier, Springer, Tailor and Franacis, Wiley and many more have been collected and reviewed. This paper concludes that renewable energies can be used efficiently and in a smart way by using the smart grids. However, the smart grid technology is not mature enough and needs more research on the same.

Role of smart grid in renewable energy: An overview

The installed capacity of photovoltaic (PV) systems globally reached 177 GW at the end of 2014 The annual rate of installations, 387 GW in 2014, continues to increase A large part of this is installed as residential systems connected to low voltage (LV) networks The majority of the LV distribution networks are radial, unbalanced with respect to loads and feeder structures and have high R/X ratios The large scale deployment of PV within the LV distribution networks is limited by voltage quality problems, particularly over voltages and unbalance Development of proper mitigation techniques is essential to effectively and efficiently manage high penetration of PV within the LV distribution networks A number of techniques have already been developed and implemented in LV distribution networks to alleviate those problems This paper provides an extensive review of the present status, impacts and technical challenges of PV penetration in LV distribution networks In addition, the review comprehensively examines the commercially available and emerging mitigation methods and provides a framework that systematically explores the full range of technical methods and limitations for PV impact mitigation These will provide a useful framework and strong point of reference for the researchers working further in this field

A review of high PV penetrations in LV distribution networks: Present status, impacts and mitigation measures

In grid-connected photovoltaic systems, a key consideration in the design and operation of inverters is how to achieve high efficiency with power output for different power configurations. The requirements for inverter connection include: maximum power point, high efficiency, control power injected into the grid, and low total harmonic distortion of the currents injected into the grid. Consequently, the performance of the inverters connected to the grid depends largely on the control strategy applied. This paper gives an overview of power inverter topologies and control structures for grid connected photovoltaic systems. In the first section, various configurations for grid connected photovoltaic systems and power inverter topologies are described. The following sections report, investigate and present control structures for single phase and three phase inverters. Some solutions to control the power injected into the grid and functional structures of each configuration are proposed.

L. Hassaine

Papers

Overview of power inverter topologies and control structures for grid connected photovoltaic systems

Digital power factor control and reactive power regulation for grid-connected photovoltaic inverter

Power control for grid connected applications based on the phase shifting of the inverter output voltage with respect to the grid voltage

Experiment and simulation of electrolytic hydrogen production: Case study of photovoltaic-electrolyzer direct connection

Adaptive fuzzy control with an optimization by using genetic algorithms for grid connected a hybrid photovoltaic–hydrogen generation system