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Development of Higher-voltage Direct Current Power Feeding System for ICT Equipment
Abstract
This article describes the development of a higher-voltage (approximately 400 V) direct current power feeding system for information and communications technology (ICT) equipment. It has higher efficiency than conventional alternating current systems, which can reduce the system cost. High-efficiency power feeding systems are an effective way to reduce ICT power consumption as well as low-powerconsumption ICT equipment such as routers and servers and high-efficiency cooling systems.
... Worldwide attention has recently been focused on the idea of distributing direct current (DC) electric power inside datacenters and supplying the servers directly with higher-voltage DC (HVDC) power feeds as a key technology for reducing losses [], [2]. In response to this trend, international standards organizations such as the ITU-T (International Telecommunication Union, Telecommunication Standardization Sector) and IEC (International Electrotechnical Commission) are now working on the standardization of device specifications, system configurations, safety measures, and component/device specifications that are needed for the practical implementation of this technology. ...
Higher-voltage direct current (HVDC) power feeds are attracting attention as an efficient means of supplying 380-V DC electricity to datacenters and telecommunications facilities, and it is expected that this technology will eventually be put to practical use in many places worldwide. In this article, we describe the characteristics of HVDC power feeds and the international standardization efforts related to this technology, including an overview of ITU-T Recommendation L.1200 of May 2012 ("Direct current power feeding interface up to 400 V at the input to telecommunication and ICT (information and communications technology) equipment").
... The efficiency of the DC distribution is analyzed in the previous studies in high-voltage DC transmission, in the large PV installations, in the offshore wind farms, in the shipboards and in data centers [5][6][7][8][9]. In addition, the efficiency of the residential DC supply is analyzed in [10]. ...
The low voltage direct current (LVDC) distribution network is a promising solution to be considered in future smart grids. For facilitating the design of cost effective LVDC distribution networks, the total losses of the network with different configurations are evaluated and compared. The possibility to connect the customer loads asymmetrically, when the bipolar DC network is used and the fact that the customer has single-phase loads, which lead to phase-Asymmetrical loading of a three-phase converter, are taken into account. According to the results presented in this paper, the highest efficiency is achieved when the ungrounded LVDC distribution network is supplied by two series connected line converters. When the length of the bipolar network is 600 m at maximum, three-phase load converters should be connected to 750 V DC with a 400V/400V isolation transformer. Instead, while the length of the DC network is over 600 m, the maximum efficiency is achieved when the unipolar network configuration is used by connecting the load converters to 1500 V DC with a 800V/400V isolation transformer.
... As widely acknowledge, power consumption and performance of ICT equipment, (e.g. servers, routers,…) are strictly bounded [47], and a clear evaluation of the benefits on performance and energy savings brought about by any allocation strategy often breaks into the trade-off between two competing goals [48]. As already noted by us [18] and by other authors [17] the actual challenge is trying to maintain a satisfactory level of performance without increasing the energy costs. ...
The flexible and pay-as-you-go computing capabilities offered by Cloud infrastructures are nowadays very attractive, and widely adopted by many organizations and enterprises. In particular this is true for those having periodical or variable tasks to execute, and, choose to not or cannot afford the expenses of buying and managing computing facilities or software packages, that should remain underutilized for most of the time. For their ability to couple the scalability offered by public service providers, with the wider Quality of Service (QoS) provisions and ad-hoc customizations provided by private Clouds, Hybrid Clouds (HC) seem a particularly appealing solution for customers requiring something more than the mere availability of the service.
... Considering the annual electricity usage in United States, which is more than 3800 billion kW h [4], it is seen that more than 75 billion kW h of electricity is consumed annually by data centers. In a typical data center, around 40-50% of electric power supply is consumed by IT equipment; 30-40% is consumed by cooling system and the rest is consumed by other facilities such as power conversion and distribution units, and lighting [5][6][7]. Almost all the energy consumed by the IT equipment is converted to waste heat. Therefore, in the United States alone, $32.2 billion kW h of http://dx.doi.org/10.1016/j.apenergy.2014. ...
... As widely acknowledge, power consumption and performance of ICT equipment, (e.g. servers, routers,…) are strictly bounded [16], and a clear evaluation of the benefits on performance and energy savings brought about by any allocation strategy often breaks into the trade-off between two competing goals [17]. As noted by other authors [18] the actual challenge is trying to maintain a satisfactory level of performance without increasing the energy costs. ...
Hybrid Clouds couple the scalability offered by public Clouds with the greater control supplied by private ones. A (hybrid) Cloud broker acting as an intermediary between users and providers of public Cloud services, may support customers in the selection of the most suitable offers, optionally adding the provisioning of dedicated services with higher levels of quality.The paper presents a Cloud brokering algorithm delivering services with different level of non-functional requirements, to the private or public resources, on the basis of different scheduling criteria. With the objective of maximize user satisfaction and broker’s revenues, the algorithm pursues profit increases by reducing energy costs, through the adoption of energy saving mechanisms. A simulation model is used to evaluate performance in terms of broker’s revenue, user satisfaction and energy behavior of various allocation policies. Simulation results show that differences among policies depend on system loads and that the use of turn on and off techniques greatly improves energy savings at low and medium load rates.
This article introduces the status of research and development being performed by NTT Energy and Environment Systems Laboratories based on the concept of information and communications technology (ICT) combined with energy called "ICT × energy". This should lead to systems capable of ensuring stable power supply, saving energy, and shifting load peaks as well as to technologies that use smart energy management.
Development of waste heat-driven absorption-based cooling system is inspired for the need of removing high heat flux from the sustainable data centre environment. This paper presents a simulation study of single-stage Lithium Bromide–Water (LiBr–H2O) vapour absorption heat pump for chip cooling. In the present work, a complete thermodynamic analysis of the single-stage LiBr–H2O vapour absorption-based heat pump for chip cooling without a solution heat exchanger is performed and a user friendly graphical user interface (GUI) package including visual components is developed by using MATlab (2008b). The effect of chip heat flux on COP (Coefficient of Performance), flow rates and conductance is examined using the developed package. The model is verified using the data available in the literature which indicates that there is a greater reduction in the absorber load. The influence of chip heat flux on the performance and thermal loads of individual components are studied, and it is concluded that COP decreases from 0.7121 to 0.68924 with increase in chip heat flux.
In this article, we introduce activities aimed at spreading the use of higher-voltage direct current (HVDC) power-feeding systems. We introduce the state of development of HVDC systems, improvements in operability, and standardization trends.
This article provides an overview of NTT Energy and Environment Systems Laboratories' research and development (R&D) objectives and initiatives to move the country toward a green society. Our ambitious R&D agenda is based on three key concepts-Green ICT, Green materials, and Governance by Green-with the goal of completely eliminating CO2 emissions and waste generated by the NTT Group's business activities by the year 2050.
We discuss the advantage of highly efficient and reliable higher-voltage direct current (HVDC) power feeding systems and the standardization activities for the power interface conditions in ICT equipment. With the recent spread of Internet services, the power consumption of ICT services is increasing annually. Many data center servicers want to decrease the power consumption of ICT equipment, cooling systems, and power feeding systems. HVDC power feeding systems have recently drawn attention due to their high efficiency and reliability. Such systems are more efficient than AC power feeding systems and are as reliable as conventional -48-V DC power feeding systems. However, the feeding voltage of HVDC systems is DC 380-V, which is higher and different than the conventional voltage of DC -48 V. ICT equipment is needed to change the power supply unit's interface. Therefore, we are actively standardizing the power interface condition of power supply units in ICT equipment. The European standards bodies of the European Telecommunications Standards Institute and International Telecommunication Union consented to the power interface conditions this year.
This paper presents the design and implementation of an energy management system (EMS) with fuzzy control for a dc microgrid system. Modeling, analysis, and control of distributed power sources and energy storage devices with MATLAB/Simulink are proposed, and the integrated monitoring EMS is implemented with LabVIEW. To improve the life cycle of the battery, fuzzy control manages the desired state of charge. The RS-485/ZigBee network has been designed to control the operating mode and to monitor the values of all subsystems in the dc microgrid system.
In the past Intelec, many presentations and DC panel have shown the advantage of using 48V DC power supply for Telecom. Reliability, simple scalability, modularity, low cost maintenance, reduced footprint, higher power efficiency than AC back-up architecture, high safety.
To realize an eco-house, a new direct current (DC) distribution system has received widespread attention. This paper has proposed countermeasures to fundamental problems which make difficult to achieve a high-speed PLC over the existing alternating current (AC) systems. To reduce the signal attenuation of the conventional low-voltage (LV) power-line cables made from vinyl insulator, it is recommended to use cables made from polyethylene insulator. It has been also recommended not to use the single pole and 3-way switches supposed to be cut into the hot conductor, and hand-made joint boxes in order to make the electrical balance of the channel high. To prove these proposals, a DC power-line system of 1.5kW capacity was built and the throughput was measured. The proposed simultaneous dual-mode system performed 1.9 times better throughput at maximum comparing with the conventional single-mode system. From these observations, a scenario for a 1Gbps Personal Area Network (PAN) over the new DC power-line channels is proposed.
This paper describes fuse blowing characteristics for high voltage direct current (HVDC) power supply systems. We simulated the difference of the voltage and current waveforms between 380 V (HVDC) and 48 V (conventional) using a new fuse model and derived the fuse blowing characteristics that are required for HVDC. We calculated the relationship between the maximum voltage and arcing time and connected the fuse model parameters to the physical parameters. From the results, we devised a technique for making a good fuse that balances arcing time and maximum voltage. Moreover, we calculated the effect of the voltage fluctuations due to a fuse blowing in an HVDC power supply system. To have smaller voltage fluctuations, not only must the fuse be good but the system must be appropriate. We propose design points that will decrease voltage fluctuation in the system. They will lead to add safety and maintain the high efficiency of HVDC power supply systems.