Detecção e localização de distúrbios transitórios em linhas de transmissão de energia utilizando sensores sem fio

• Ano de defesa: 2010
• Autor(a) principal: Denio Teixeira Silva
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Engenharia Elétrica; Engenharia elétrica
• Link de acesso: http://hdl.handle.net/1843/BUOS-8FAJLG

This work presents an application of wireless sensors in power transmission lines to detect and locate impulsive transient disturbances caused by direct lightning strokes to the line and short circuits. Direct stroke and short circuit on phases produce transient currents of great magnitude and high rate of change. The return current of the lightning stroke to shield wire flows through the wire and through the towers to earth. The short-circuit produces a transient current that induces a significant voltage along the shield wire. Similarly, a direct stroke to phase cable induces a significant voltage in the shield wire. This induced voltage produces a current with high peak value that flows though the wire and through the towers to earth. Wireless sensors installed on top of the towers, can measure these currents flowing in the towers. The transient component of the currents is greater in the towers close to the stroke or to the position of the short-circuit. This behavior is used to locate the transient disturbance. Each sensor measures the peak value of the transient current, and the peak value of the rate of change of current. Only the sensors close to the disturbance measure significant value of current in the shield wires. These analogical measurements are converted into binary data by the sensors and sent via a wireless network to a computer. In this computer, the values of the measurements are analyzed by the location software to identify whether the transient disturbance is a direct stroke or a short-circuit, to locate the span where the transient disturbance occurred, and to evaluate the power in the case of a direct stroke. In this thesis, it is used a system approach and the main issues of the whole system are analyzed: which measurements should be made, how the measurements are made, how the measurements are sent for processing on the computer location, and how this information is processed. Another important issue, studied in the thesis, is how to supply energy to sensors without using photovoltaic cells and batteries, which need periodic maintenance. It is presented a proposal to use the 60 Hz steady state current induced in the shield wires to supply power to the sensors, and to use super capacitors to replace the batteries.