De Oliveira B.G.M.,Federal University of Pernambuco |
Santos M.R.,Federal University of Pernambuco |
De Oliveira A.J.B.,Federal University of Pernambuco |
De Melo M.T.,Federal University of Pernambuco |
And 4 more authors.
SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference Proceedings | Year: 2013
This paper presents the conception and simulation results of a switched smart antenna array to be used for a reliable communication between a Distributor of Electricity and its automation devices such as remotely supervised and controlled electrical switches. The smart antenna system controls the direction of the radiation main lobe, increasing the transmitted power density, which allows the establishment of communication with devices located in shadow regions. This prevents new repeater stations to be installed for the same purpose. Also laboratory tests with Beamforming Controller Circuit are here reported. © 2013 IEEE.
De Medeiros L.H.A.,Federal University of Pernambuco |
Rosas P.A.C.,Federal University of Pernambuco |
Lins Z.D.,Federal University of Pernambuco |
Ferreira H.L.,Companhia Energetica de Pernambuco CELPE |
And 2 more authors.
Electric Power Systems Research | Year: 2011
This paper presents an analysis of the experimental measurements of fast transients and their electromagnetic interference on the protection system in air isolated distribution substations. Transients were recorded in the relay inputs of potential and current transformers due to switching operations in a 69 kV bus bar. A peak overvoltage of up to 6.5 kV and frequencies of around 1 MHz and above, were recorded in secondary circuits that are rated 115 V. The current presented fast transients with relatively small amplitudes and lower frequencies than the recorded voltages. The transients caused relay failures leading to the unnecessary disconnection of the substation. Transients are supposed to be related to radiated and conducted interferences caused by the electric arc during switching operations. Transient voltage and currents are analyzed, and the results are compared with others from the literature. Some solutions are presented to mitigate the failures of the protection relays. © 2011 Elsevier B.V. All rights reserved.
De Lima M.A.X.,Companhia Energetica de Pernambuco CELPE |
Clemente T.R.N.,Federal University of Pernambuco |
De Almeida A.T.,Federal University of Pernambuco
International Journal of Electrical Power and Energy Systems | Year: 2016
The responsibility of Brazilian companies which produce and distribute electricity is to comply with standards and requirements about the level and quality of voltage that meet consumer demand. One of the strategies adopted to maintain control over the operations of the electricity supply is that of installing voltage regulators throughout the distribution network. However, this activity requires the management of available resources in terms of investing in equipment installations, and this is a major challenge for companies in the electricity sector. From this perspective, this article proposes a multicriteria model for prioritizing locations for installing voltage regulators in an electricity distribution network, which takes into consideration technical, regulatory, economic and social criteria to evaluate the consequences of installing voltage regulators and their operational performance. Thus, this paper presents an application of the Additive-veto Model for ranking multicriteria decision problems so as to relate the performance assessed by the decision-maker for allocating equipment to the set of available locations. © 2015 Elsevier Ltd.
Brito M.E.C.,Companhia Energetica de Pernambuco CELPE |
Limongi L.R.,Federal University of Pernambuco |
Cavalcanti M.C.,Federal University of Pernambuco |
Neves F.A.S.,Federal University of Pernambuco |
Azevedo G.M.S.,Federal University of Pernambuco
Electric Power Systems Research | Year: 2014
The large number of computers and other sensitive electrical loads connected to power grid are directly affected by grid disturbances. The vast majority of these disturbances is related with voltage transients, such as voltage sags. This paper deals with a step-dynamic voltage regulator designed to protect the load against the effects of these voltage transients. The ideia is to use a simple structure based on the insertion of a cascaded reduced-power series transformers between grid and load. It makes possible the use of actual mains voltages to compensate and mitigate the disturbances. It will be shown that the proposed solution can fully compensate or mitigate the faults that occur more frequently in power systems. Experimental results obtained on a 5 kVA prototype demonstrate the feasibility of the proposed solution. © 2013 Elsevier B.V. All rights reserved.