Zimath S.L.,Reason Tecnologia |
Ramos M.A.,Furnas Centrais Eletricas |
Filho J.S.,Furnas Centrais Eletricas |
Beck J.M.,Eletronorte |
Mueller N.,Reason International
2010 63rd Annual Conference for Protective Relay Engineers | Year: 2010
Transmission utility companies continuously strive for high availability of their lines. When a line is off service following a permanent fault, a significant amount of the time during the restore the line can be attributed to locating the point of the fault. This paper shows how this time can be significantly reduced using highly accurate traveling wave (TW) fault locators. It describes location results of several faults in three separated transmissions lines. The collected data are compared to those obtained by considering one- and two-end impedance location algorithms for the same faults. It also highlights the unique characteristics of Reason fault locators to overcome common problems of other TW solutions existing in the market. ©2010 IEEE.
Sousa J.J.L.,Chesf |
Leitao L.T.S.,Chesf |
Costa M.M.,Eletronorte |
Faria M.C.,Furnas Centrais Eletricas
20th IMEKO World Congress 2012 | Year: 2012
This paper has the purpose to show how the instability of travelling standards can affect the results of an interlaboratory comparison program, and how to evaluate its influence in the determination of these results, in order to not compromise the assessing of a laboratory when En value is used for this purpose. In this work are presented and discussed five options of instability compensation of the travelling standard. Copyright © (2012) by the International Measurement Federation (IMEKO).
Rosolem J.B.,Brazilian Center for Research and Development in Telecommunications |
Floridia C.,Brazilian Center for Research and Development in Telecommunications |
43rd International Conference on Large High Voltage Electric Systems 2010, CIGRE 2010 | Year: 2010
Classical systems for monitoring hydro generators normally use the following variables: •Turbine: pressure of spiral duct, cover and discharge; •Generator: copper, core and cooling water temperature, partial discharges, core vibrations, cooling water pressure; •Bearings: axis oscillations, cover vibrations, metal and oil temperatures; •Excitation system: slip ring temperature, current, voltage, rotor temperature, electric field. In these systems, electric variables and temperatures are transmitted from the supervisory system by means of communication device. The other variables as oscillations, vibrations, pressures, partial discharges and electric field are available by means of specific sensors, connected directly or through electronic devices to a computer, which condition and organize the data. This structure of monitoring systems, despite its important use to predict failures, has important installation cost and requires periodic calibration of the measurement chains. The development of sensors based on fiber optics technology offers new capabilities for the monitoring systems: the first available sensors are of the direct or intrinsic type, namely that the sensor is inlaid in the fiber, such as temperature, pressure, vibrations sensors. Eletronorte, a Brazilian utility company located in the Amazon region, interested in monitoring systems that are simple, more trustworthy and less onerous, decided to invest in the development of the two more required and not yet available sensors in the market: a sensor for oscillation of shaft and other for partial discharges. As the rotor is a component of the generator without supervision, Eletronorte also developed an optic communication system for the data measured at the rotor (temperature mainly) with optic sensors that transmit the measured data to the part fixed on the stator. The sensor of axis oscillation is of the indirect or extrinsic type, when the transducer acts in the fiber, using the magnetic properties of the sensor to intervene with implanted grid of Bragg in the fiber. The partial discharges sensors are of the hybrid type, when the fiber takes the information of the transducer, an antenna type minder that catches the induced impulses of partial discharges, transforms them into luminous impulses, which are then transmitted by the fiber. The communication system of data measured in the rotor consists of two collimators, one installed at the rotor that receives the measurements carried out by the rotor embarked optic sensors, and the other in the stator, that catches the measured signals each time that the mobile collimator passes in front of it, enabling the direct measurement of the temperature of the polar regions and the wheel deformation. Considering that the current technology allows to place 80 optic sensors in a fiber loop, and that a total monitored hydro generator would need approximately 150 measurement points, two optical-fiber loops can transmit the monitored data; therefore for reliable measurement, the number of loops can be increased decreasing the points distributed in each loop, in a way to get a control system and optoelectronic measurement multipoint and multiloop. Optic measurements are made by an interrogator module and converted into electronic and digital signals, enabling its treatment by a computer. A total optical system in the hydro generator environment guarantees an improved reliability because of its immunity to electromagnetic interferences.
Hallwass G.,Federal University of Rio Grande do Sul |
Lopes P.F.,Federal University of Rio Grande do Norte |
Juras A.A.,Eletronorte |
Silvano R.A.M.,Federal University of Rio Grande do Sul
Environmental Management | Year: 2011
The management of small-scale freshwater fisheries in Amazon has been based usually on surveys of urban markets, while fisheries of rural villages have gone unnoticed. We compared the fishing characteristics (catch, effort and selectivity) between an urban market and five small villages in the Lower Tocantins River (Brazilian Amazon), downstream from a large reservoir. We recorded 86 and 601 fish landings in the urban market and villages, respectively, using the same methodology. The urban fishers showed higher catch per unit of effort, higher amount of ice (related to a higher fishing effort, as ice is used to store fish catches) and larger crew size per fishing trip, but village fishers had a higher estimated annual fish production. Conversely, urban and village fishers used similar fishing gear (gillnets) and the main fish species caught were the same. However, village fishers showed more diverse strategies regarding gear, habitats and fish caught. Therefore, although it underestimated the total amount of fish caught in the Lower Tocantins River region, the data from the urban market could be a reliable indicator of main fish species exploited and fishing gear used by village fishers. Monitoring and management should consider the differences and similarities between urban and rural fisheries, in Amazon and in other tropical regions. © Springer Science+Business Media, LLC 2010.
Zimath S.L.,Reason Tecnologia S.A. |
Dutra C.A.,Reason Tecnologia S.A. |
Matos R.R.,Reason Tecnologia S.A. |
De Oliveira L.B.,Reason International |
And 2 more authors.
IET Conference Publications | Year: 2014
Because the market regulation in Brazil, power transmission companies are paid for the availability of their lines. When a fault occurs and the line becomes unavailable, such companies are penalized for the time the line is off service. Thus, fault location systems that can reach higher accuracy to estimate the fault location minimize the downtime of the line and, therefore, the application of penalties. Impedance-based fault location methods usually are not efficient in high impedance events. Traveling wave-based fault location technology provides good estimation independently of the type of the fault. This article shows the experience of implementing a traveling waves-based fault location system in Eletronorte (Brazil) transmission lines, which because of their geographical location and the climate of the region, have a large incidence of high-impedance faults. After a large number of events, the results show the reliability of fault location by using traveling waves, even if the wave fronts are shown with higher attenuation compared to those produced by low-impedance faults.
Nogueira F.G.,Federal University of Ceará |
Barra W.,Federal University of Pará |
Da Costa C.T.,Federal University of Pará |
Barreiros J.A.L.,Federal University of Pará |
De Lana J.J.,Eletronorte
IFAC-PapersOnLine | Year: 2015
In this paper, the application of linear parameter-varying (LPV) identification and control methods for designing and performance evaluation of an adaptive power system stabilizer (PSS) is presented. The target control objective is to improve the damping of the dominant electromechanical oscillating mode in the power system. The performance of the LPV PSS controller has been assessed by means of experimental tests carried out on 10 kVA small-scale power system. For design purposes, an LPV ARX model was estimated from experimental tests, for a wide range of operating conditions. The LPV controller was tuned via an optimization problem, in the form of a Parameterized Linear Matrix Inequality (PLMI). The solution was obtained through a sum-of-squares relaxation. Both the LPV model and the LPV-PSS have an explicit dependency on system scheduling variables, namely the active and reactive powers measurements. Therefore, the LPV-PSS was designed to ensure stability and performance for a wide range of operating conditions, an objective usually difficult to obtain by using fixed parameter controllers. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.
Pereira C.S.,Federal University of Pará |
Almeida A.D.C.,Federal University of Pará |
Rocha B.R.P.,Federal University of Pará |
Electric Power Systems Research | Year: 2015
The vulnerability under lightning conditions of stretches of the 1500 km long electrical transmission line Tucurui-Oriximina-Manaus over dense Amazon forest canopy and river crossings is evaluated using a leader progression model (LPM) called ModSalto. We find vulnerability windows (low protection or unsafe) in all crossing stretches that use high towers to comply with environmental restrictions. The values of lightning flashover rates (LFR) reach 0.8277 flashover/year or an equivalent period of 14.49 months for stretches of river crossings, and 0.3403 flashover/year or an equivalent period of 35.26 months for stretches of forest canopy crossing. These numbers are above the computed equivalent ANEEL bidding figure of 0.15 flashover/year for that TL. This methodology uses a map of yearly lightning frequency produced with data from STARNET and SIPAM LLS and the level of lightning protection was evaluated with the electro-geometric model (EGM). © 2014 Elsevier B.V. All rights reserved.
Limao R.,Federal University of Pará |
Da Silva R.,Federal University of Pará |
Sena A.,Federal University of Pará |
44th International Conference on Large High Voltage Electric Systems 2012 | Year: 2012
1. We have determinate what components present the most frequent and expansive defects, and focused the action at them. We have classified the five main components, following our experience and previous Cigre report: Stator, specially the insulation losses; Bearings; Slip ring; Rotor; Turbine. 2. For each component we selected the most representative variables to observe its wearing. • For the stator wearing, temperature of winding, cooling water and core are available, as well as tension, current, active and reactive power furnished by the supervision system; we measure also partial discharges (01 point for each winding per phase), air gap, and vibrations of the core. • Bearings are controlled by the measure of oil temperature, metal temperature, shaft oscillations, and vibrations of the bearings covers. We consider also air gap measurement. • We control the slip ring measuring its temperature by IR sensor; the excitation current and voltage are available from the supervision system. • For the rotor, we only dispose in the moment the temperature, measured by indirect method; in a next future, we will be able to measure data on the rotor, as temperatures and strains with a new optical system, actually in experimental test. • The turbine is represented by the pressure of spiral box, cover and suction. 3. The next step is to describe the probable defect in formation, using the knowledge and the experience of our project and maintenance technical staff; in this first work, we have considered only stator, bearings and slip ring; some example are described below: • For the stator: heating of winding and core, losses of insulation, slackening of the core foils⋯ • For the bearings: heating of oil and metal, unbalance rotor, shaft inclination or deformation⋯ • For the slip ring: bad commutation by the brushes on the ring, carbon film formation incorrect⋯ 4. We treat the variables by the fuzzy method, determining for each one limit for normal and alarm values, diagram of her evolution. After that we determine the logic rules attaching the observed variables with the probable defects; the state of each variable out off the normal condition is showed as a weight, more important when the variable is going to critical situation; the combination of each variable point considered that the rule permit to estimate the probability for the formation of each defect. For example: • Stator: losses of insulation is associated with PD's measurement, core vibrations, and sometimes with core heating; • An unbalance rotor is associated with shaft oscillations, but also with bearings temperature increase; • Slip ring: the consequence of a bad commutation is directly an increase of the surface temperature; but this one must be measured at the same excitation condition; We verify the exactness running the rules with a fictitious data bank, where we simulate abnormal conditions of the representative variables.
Hudon C.,Hydro - Quebec |
Guddemi C.,Hydro - Quebec |
Gingras S.,Hydro - Quebec |
Leite R.C.,Eletronorte |
Mydlarski L.,McGill University
34th Electrical Insulation Conference, EIC 2016 | Year: 2016
Rotor temperatures of field windings are seldom measured, as permanent installation of sensors on the rotor is often difficult and can present undesired risks. However, new possibilities exist with the use of fiber Bragg gratings (FBGs). Up to 20 sensors can be mounted in series in a single fiber. Moreover, several fibers can be used in parallel, and the signal passed from the rotor to the stator through a multichannel optical rotating joint. A demonstration of such a use of FBGs has been undertaken in a Hydro-Quebec power plant, where 32 pole-to-pole connections and 28 poles were instrumented. Measurements were carried out during a heat run test and FBG results are compared with average temperature calculated from voltage and current. © 2016 IEEE.
News Article | December 17, 2015
An 850kW Ciel et Terre floating PV project in Hyogo prefecture in southern Japan France’s Ciel and Terre and local partner Sunlution have secured R$100m ($26m) from Brazilian federal power companies Chesf and Eletronorte to build and test 10MW of floating PV in Brazil over the next three years.