SETOR ELÉTRICO : NA LINHA DAS IMPREVISIBILIDADES PAULO LUDMER - REVISTA ELETRICIDADE MODERNA

"NINGUÉM SE ENGANE: ÁGUA E ENERGIA SERÃO MAIS CARAS E DE PLANEJAMENTO MUITO COMPLEXO ATÉ PELO MENOS 2017 "

PAULO LUDMER
JORNALISTA,ENGENHEIRO,PROFESSOR,CONSULTOR E AUTOR DE LIVROS COMO DERIÇA ELETRICA E SERTÃO ELÉTRICO
WEBSITE; www.pauloludmer.com.br
FONTE DA NOTICIA
REVISTA ELETRICIDADE MODERNA NOVEMBRO2014-ANO XLIII-EM-488
LINK REVISTA
http://www.arandanet.com.br/midiaonline/eletricidade_moderna/2014/novembro/index.html

Harmonics Reduction in High-Efficiency Operation of Double-Conversion UPS Lorenzo Giuntini

Abstract
UPS are used to protect critical loads, and double-conversion is often the preferred choice. While
providing optimum protection, this topology offers limited efficiency. Some double-conversion UPS
feature a high-efficiency (ECO) mode, with the load normally fed via the bypass path. In this
operating mode, load current harmonics may be let through towards the utility, and may induce a high
load on the neutral conductor. In this context, this paper discusses Advanced ECO Mode topologies
that reduce neutral current and mitigate harmonics resulting from non-linear or unbalanced load.

Introduction
 Uninterruptible Power Supplies (UPS) provide power conditioning and backup power for critical and sensitive equipment, the typical example being Information Technology (IT) equipment in data centers. Double-conversion topology is often the preferred choice, especially for larger UPS installations (as a matter of fact, double conversion topology dominates the market for UPSs larger than 5 kVA used in US data centers [1]). While providing optimum protection, double conversion topology may not offer the highest efficiency: best-in-class efficiency for double conversion transformer-based UPS is around 94 %. Actual efficiency may further drop depending on UPS operating conditions, particularly the load level. In fact, UPS losses may account for 10 % of the total power consumed in a data center [2]. Given the challenges posed by greenhouse gases (GHG) emission targets, energy intensive facilities are looking at alternative UPS operating modes to increase the overall site efficiency. Some double conversion UPS feature a high-efficiency mode (typically referred to as ECO mode), where losses are greatly reduced by feeding the load via the bypass path, with resulting efficiency exceeding 98 %. A common concern is that bypass operation may expose the load to utility disturbances. To address such concerns, previous research activity focused on protection against power quality events (such as interruptions, sags, swells, spikes, etc.) during ECO mode operation. This paper takes another perspective, focusing on current harmonics and neutral current resulting from non-linear or unbalanced load. When the UPS is feeding loads with non-linear input characteristics (such as IT equipment) via the bypass path, the resulting harmonics may potentially pollute the power system. These harmonics may induce voltage distortion and increase losses, eventually leading to premature failure of electrical equipment [3]. Additionally, triplen harmonics accumulate in the neutral conductor, and combined with unbalanced loads may potentially lead to overload of the neutral conductor and overheating of the distribution transformer [4]. In this context, this paper explores Advanced ECO Mode topologies that reduce neutral conductor loading and mitigate harmonic injection on the utility supply, presenting experimental results from testing high-power UPS installations.
LINK FULL PAPER
https://copy.com/uFvkhtpuxhNUmGxz

HIGH FREQUENCY LINK UPS SYSTEM By Emad Abdulrazzaq Rasool School of Engineering and Design Department of Electrical Engineering and Electronics Brunel University UNITED KINGDOM

HIGH FREQUENCY LINK UPS SYSTEM
A thesis submitted for the degree of Master of Philosophy
 By Emad Abdulrazzaq Rasool
 School of Engineering and Design Department of Electrical Engineering and Electronics
Brunel University January 2013

ABSTRACT
The main aim of this thesis is to propose, design, simulate and build a new UPS system which can be used for compact applications. The idea of the proposed system is to operate the transformers within the UPS at high frequency so that the size and the weight are kept to minimum. In order to achieve this aim, the transformer within the UPS system is operated at high frequency; however it also carries two 50 Hz waveforms at 180 phase shift so that the transformer does not see this 50 Hz frequency. A cycloconverter is then used to reconstruct the 50 Hz waveform for the UPS output.
The UPS system is simulated using PSPICE software at high frequency link of 500 Hz, 1 kHz, 5 kHz and 10 kHz. The simulation results show that the transformer only passes the high frequency component while the 50 Hz frequency is ‘hidden’ within the transformer. The proposed UPS system is then built using MOSFETs IRF740 as the main switches for the inverter and cycloconverter circuits. A Chipkit-uno32-development-board is used to control the MOSFET switches. Simulated and practical results show the viability of the proposed UPS system.

LINK FULL THESIS
http://bura.brunel.ac.uk/bitstream/2438/7246/1/FulltextThesis.pdf

Design of Robust Controller for Single-Phase Double-Conversion UPS System Seung-Beom Lim, Young-Min Seol, Sang-Hoon Kim, Jin-Woo Lee, and Soon-Chan Hong Dankook University, Korea, Kangwon National University, Korea

Design of Robust Controller for Single-Phase
Double-Conversion UPS System

Seung-Beom Liml, Young-Min Seo, Sang-Hoon Kim, Jin-Woo Lee, and Soon-Chan Hongl
 Dankook University, Korea,  Kangwon National University, Korea, Doowon Technical College,
Koreabus1327@hotmail.com, maniyan@nate.com, kshoon@kangwon.ac.kr, jinwoo@doowon.ac.kr, schong@dku.edu

Abstract-UPS is largely divided into passive-standby, line interactive,
and double-conversion types. In general, a double conversion
type is used at a site requiring a high reliability. The
main function of the double-conversion UPS is providing the
constant voltage, constant frequency, regardless of the linear or
non-linear load and variation of the load. In this paper, the
robust controller of the single phase double-conversion UPS is
designed and its performance is verified by both simulations and
experimentation.

Encuentro Científico Internacional 2015 de verano "François Piuzzi" Viernes 2 - domingo 4 de enero de 2015- LIMA -PERÚ

Encuentro Científico Internacional 2015 de verano -LIMA - PERÚ
"François Piuzzi"
Viernes 2 - domingo 4 de enero de 2015
Cuartel General del Ejército "Pentagonito" donde se llevó a cabo la COP 20 oficial
Programa completo preliminar
http://www.encuentrocientificointernacional.org/eci2015v/eci2015vprograma20141130.pdf

Libro de resúmenes del ECI 2015 de verano
http://www.encuentrocientificointernacional.org/eci2015v/eci2015vlibroderesumenessinmails.pdf