InteraÃÃo transitÃria entre transformadores de potencial capacitivos e linhas de transmissÃo: uma contribuiÃÃo para minimizar falhas

AUTOR(ES)

Ademar Vieira de Carvalho JÃnior

DATA DE PUBLICAÇÃO

2008

RESUMO

Coupling capacitor voltage transformers (CCVT) are widely used in power systems for monitoring, protection relays and control aplications. Failure of this equipment may cause unexpected outages of transmission lines (TL), which may result in severe penalties as imposed by the regulatory agency of the government. This fact requires speeding maintenance procedures so as to guarantee the reset of the lost operational ability in the shortest possible time, as well as development of preventive techniques to reduce the non-programmed outages. In this framework, studies have been conducted to model the CCVT focused on electromagnetic transients analyses. In the state-of-the-art, this study demonstrates that switching-off compensated TL may lead to a sustained voltage amplification in secondary of the CCVT, product of a transient interaction between the TL and CCVT, which causes thermic and dielectric stress to its components. This interaction is chiefly influenced by the design of the CCVT and the TL-compensation degree, as assessed in this work by the means of frequency response mappings, measurements of important parameters of diferent designs of CCVT, and computer simulations. Besides, this investigation presents oscillographic records of the transmission systems of the Companhia Hidro ElÃtrica do SÃo Francisco (CHESF), which illustrates the existence of such a phenomenon. It is worthwhile to emphasize that the interconnection and expansion of the power system network may require more switching-off TL to voltage control, which in turns mean an increase of the abovementioned phenomenon

ASSUNTO(S)

sobretensÃo overvoltage coupling capacitor voltage transformer (ccvt) grau de compensaÃÃo da lt linha de transmissÃo (lt) transformador de potencial capacitivo (tpc) interaÃÃo transitÃria degree of compensation of tl transmission line (tl) transient interaction engenharia eletrica

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