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Autonomy improvement of data center backup sources with supercapacitors
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In addition to location, internal security, connectivity and data security, the power system is a very important issue to be taken into account in achieving a data center. Regarding this, professionals point out a number of important elements: grid topography, entry points into the data center's building, generators, Automatic Transfer Switch type systems, Power Distribution Units, air and cooling distribution system, up to considering the age of batteries inside the UPS which supply the servers. This particular attention to the supplying power system is explained by the essential purpose of a data center that has to ensure business continuity, independently on the main power supply failure. In this context, the paper analyses the possibility to use supercapacitors to increase the autonomy and, for the specific case of the Zipper Data Center Romania, proposes a solution to increase the uptime of a backup source equipped with a battery by connecting a supercapacitor in a proper point.
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... Network management systems manage uninterruptable power supplies (UPSs.) Failure to do so could result in irreversible consequences and have an impact on national security [4]. ...
... Combining wind and solar with storage provides the most significant benefit to grid operations and can achieve the most important economic value [26], The battery technology influenced energy storage and use on-demand [22], National Security, Data Centres etc. In addition to standby power generators, they use expensive technologies such as Super Capacitors [4]. It became a need of any modern grid to have some storage methodology to store renewable energy when produced abundantly and use later to meet the demand in the grid [13,25]. ...
... This article has sighted one of the oldest energy storage cells dating back to 220BC [4], which goes on to prove the importance of energy storage. It is also highlighted that while combining wind and solar with storage provides the most significant benefit to grid operations and has the potential to achieve the most outstanding economic value [32]. ...
The befalling of natural disasters has been experienced at an alarming level in the last decade due to discharging excessive amounts of CO2 into the atmosphere. The world needs to decarbonise itself sooner than later. To combat environmental impact and the climate change, several key initiatives were taken by countries like the UK, Japan, Europe, and Canada. That includes decarbonising the power sector entirely by bringing in renewable energy in place of fossil fuel on an agreed timeline. Many countries have committed to zero emission by 2050. However, it will not be easy to depend on 100% of renewable energy grid without renewable energy storage capability to assure grid stability. Therefore, this publication's key fundamental objective is to discuss the most suitable energy storage for energy generated by wind. A review of the available storage methods for renewable energy and specifically for possible storage for wind energy is accomplished. Factors that are needed to be considered for storage selection and the requirements are discussed. Wind farm capacity is one of the essential parameters that could affect selection procedures. It is recommended that detailed calculations be made of available energy and the excess power amount to be stored. However, the article discusses the most viable storage options such as liquid metal batteries grid embedded storage for frequency and voltage stability and produces green Hydrogen from surplus wind energy, especially in Sri Lanka.
... The solution proposed in section III can be optimized so that the extension of UPS autonomy to be more than 4.64 minutes -obtained by integrating 4 kg of supercapacitors with energy density of 85 Wh/kg, to supply the loads through a power distribution unit (PDU), in parallel with the battery [14]. Assuming that the supercapacitor is charged directly from the battery, optimization will be done by determining and setting in EBS (the electronic battery monitoring system) the minimum current that battery need to provide, sufficient for supercapacitor to further supply K loads. ...
... In the place of consumption for which has been conducted the study (Zipper Data Center Romania) there are seven loads that require total 9A (data center consumption was reduced by 68% through virtualization). According to supercapacitor dimensioning analysis of [14], are retained values: C=6.3 F, U max =10.8V and I=14A. The supercapacitor can therefore support supplying the highest of the K loads, according to: ...
The vulnerability of electricity consumers must be decreased by integrating specific energy storage systems, which can be used in any situation. As energy distribution and consumption are not constant, the storage units (for backup) must be as high capacity and total availability to streamline the complete system. This paper proposes an objective function of charging an UPS integrated hybrid source (battery and supercapacitor) and a method for optimizing the supply of loads in a critical place of consumption through the UPS with hybrid structure, increasing the autonomy of backup source and its time of re-entry into service.
Energy is a fundamental human right and a privilege; therefore, it is one of the primary responsibilities of any Government to provide it to its population without any discrimination. Sri Lanka is an island nation in the Indian Ocean located south-east of India. Hence, the Electricity grid is isolated and managed independently. The energy sector is regulated by an independent institution, namely, the “Public Utilities Commission of Sri Lanka” (PUCSL). Sri Lanka approximately has 5.5 million households, and as per the recent ratings of the World Bank, it is elevated to an upper-middle-income country. There is a high demand for electricity due to the increasing urban population and the way of life. According to the most recent statistics, the annual total electricity demand is about 15,000GWh. Electricity in Sri Lanka is generated using three primary sources: 9507GWh from thermal power (which includes coal and fuel oil) and 4641GWh from hydropower and other non-conventional renewable energy sources (solar power, wind power, biomass and mini hydro). The total installed capacity of all NCRE is approximately 177MW. The Government has paid considerable attention to increasing the percentage of renewable energy evacuation to the national grid with the aim to achieve energy self-sufficiency by 2030 while the country is aiming to increase its generation capacity to 6,900MW from its conventional resources by 2025. Wind energy potential in Sri Lanka is considered to be exceptional, and it could well reach the installed capacity of 24,000MW onshore. However, a higher capacity could be derived from offshore wind in the Northern and Northwestern provinces of Sri Lanka. The Government has proposed to expand the wind generation to around 1GW by 2034 and thereby to achieve the status of carbon neutrality by 2050. The present task is to check the feasibility of meeting the country’s energy demand solely with wind energy while keeping the existing hydro capacity as stability control and emergency power.KeywordsOffshore windon-shore windrenewable energy in Sri LankaSri Lanka energy generationwind power
Limited availability of power resources requires that for all our daily processes and actions to find the perfect approach for saving energy. IT energy consumption is expected to double in the next five years. As statistics show that computers are switch on ¾ time for nothing, it's necessary to monitor the energetically parameters and to help the grid became more green, by eliminating "idle" regimes in the operation of computers and by automatically turning off unused components in specified functioning moments.
This paper considers the maximization of the weighted sum-rate (WSR) in multicell downlink multiple-input single-output (MISO) systems. The problem is non-convex and thus cannot be solved directly via conventional convex optimization methods. To achieve global optimality, we propose a novel monotonic optimization approach where a sensible search scheme first checks the feasibility of a chosen point and then utilizes a sequential partition method at each iteration to reduce the total number of feasibility evaluations. Besides, another relocating procedure also accelerates the convergence. Simulation results verify the improved convergence performance of the proposed approach compared with the previously proposed outer polyblock approximation algorithm and the branch-reduce-and-bound algorithm.
Power over-subscription can reduce costs for modern data centers. However, designing the power infrastructure for a lower operating power point than the aggregated peak power of all servers requires dynamic techniques to avoid high peak power costs and, even worse, tripping circuit breakers. This work presents an architecture for distributed per-server UPSs that stores energy during low activity periods and uses this energy during power spikes. This work leverages the distributed nature of the UPS batteries and develops policies that prolong the duration of their usage. The specific approach shaves 19.4% of the peak power for modern servers, at no cost in performance, allowing the installation of 24% more servers within the same power budget. More servers amortize infrastructure costs better and, hence, reduce total cost of ownership per server by 6.3%.
The given paper deals with uninterruptible power supplies with supercapacitors. Parameters of the supercapacitors and common lead-acid batteries are compared. Various opportunities of supercapacitor implementation into the uninterruptible power supplies are discussed, pros and cons are analyzed. Initial numerical comparison of energy capacity for these devices is done. Experimental testing of the supercapacitors and batteries as energy sources for a boost converter has also been made.
This paper describes the energy storage characterization for a direct methanol fuel cell (DMFC) hybrid system for light traction applications. In a first step, the DMFC stack and the energy storage were dimensioned. To dimension the energy storage, the required energy density and power density were calculated. These are influenced by the operating states of the vehicle as well as the highly fluctuating load profile. For this kind of application a high energy density as well as a high power density is needed. Therefore, super capacitors are not the energy storage of choice. As an alternative, suitable batteries were analyzed in terms of their behavior in the DMFC hybrid system. Therefore, a characterization procedure was developed consisting of five different tests. These tests were developed adapted to the requirements of the application. They help to characterize the battery in terms of energy content, high power capability during charge and discharge, thermal behavior and lifetime. The tests showed that all batteries have to be operated on a partial state of charge (pSOC) and a thermal management is very important. Especially lead-acid battery show an decrease in lifetime under a pSOC operation. Therefore, a lithium battery was identified as the suitable energy storage for the considered application.
With the development of embedded technology and Internet, it would become the future trend to implement the management of UPS on network. A monitor and control model of UPS was presented in this paper according to the standard of Megatec communication protocol based on the design and implementation of Web Server, embedded file system and the architecture software and hardware of this system. So the administrator could monitor and control the UPS anywhere with the limit to the distance and the time.
A simplified steady-state model has been developed to describe thermodynamically the operation of a centralized cooling system. This model resolves the mass and energy equations simultaneously and uses inputs that are readily available to the design engineer. The model utilizes an empirical relationship for the compressor power as a function of cooling load and key temperatures. The outputs include the chiller coefficient of performance (COP) and the compressor actual power. The model simulation results are validated with a manufacturer performance data and compared with the experimental data collected at Hewlett-Packard Laboratories site for two chillers: a variable speed and a constant speed chiller. The results of the model are found to closely match the current experimental data with less than 5% average deviation for chiller load over 10% and with a maximum deviation of 18% at 95% chiller load. For the constant speed chiller, the chiller efficiency increases with increasing load and peaks at full load. For the variable speed chiller, the chiller efficiency peaks at part loading between 40 and 80% of the chiller full load depending on the condenser water temperature. This indicates that for variable speed chillers, the chiller design has been optimized for loading less than 100% depending on the ambient conditions, customer specifications and size of the chiller. Copyright © 2010 John Wiley & Sons, Ltd.
Modern manufacturing lines are very sensible to power quality disturbances whereas voltage disturbances have been clearly identified as major problems to sophisticated continuous-process-based industries. Topic of power quality is also of crucial importance for the widespread application of renewables and deep penetration of energy sources of distributed power generation. Due to the insufficient ability of batteries to absorb power surges and spikes and to deliver high energy bursts, batteries based uninterruptible power supply systems (UPS) are simply purely suited for short-term bridging by power drop or spike compensation. To handle power surges and short-term power outages the energy market needs supercapacitors with their significant benefits in power- and peak-assist. Supercapacitors are reliable, maintenance-free, short-time power source with long lifespan and are suitable to avoid the effect of voltage twist and of electrical noise or to buffer short-term outages on the power grid. Some fields of application as well as design of supercapacitor based systems have been presented taking into account specific technical requirements on power quality systems.
The charge and discharge characteristics of lead-acid battery and LiFePO4 battery is proposed in this paper. The purpose of this paper lies in offering the pulse current charger of higher peak value which can shorten the charging time to reach the goal of charging fast and also avoids the polarization phenomena produced while charging the voltage and current signal simultaneously, supervising whole charging course of the battery, avoiding the situation of excessive charging, and ensuring the life of battery. The hardware circuit of this pulse current charger adopts the power electronic elements for the main structure, uses Digital Signal Processor as the core of the controller, and substantially decreases the volume of charger and the loss of circuit. Besides, the input power supply of this charger is utility, greatly facilitating its using or carrying, which contributes to the development of variety of electric equipments in the future.
In this paper a new soft switching bidirectional DC–DC converter is introduced which can be applied as the interface circuit between ultracapacitors and batteries or fuel cells. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. Due to achieved soft switching condition, the energy conversion through the proposed converter is highly efficient. The proposed converter is analyzed and a prototype converter is implemented. The presented experimental results confirm the theoretical analysis.