专利名称:Method for determining the electrical
insulation state of the sending end of anelectric network
发明人:Nikander, Ari申请号:EP01660057.9申请日:20010327公开号:EP1139539A3公开日:20050608
专利附图:
摘要:The invention concerns a method for monitoring the electrical insulation statusof a radial or ring-connected electric network and for detecting and locating a high-
resistance ground fault. In the method, the zero-sequence voltage (U' or U) with phaseangle, the network line-to-neutral voltages (U) with phase angles, and the sum currents(I) of the sending ends with phase angles are measured. In the method, the absolutevalue of the zero-sequence voltage change vector (ΔU) is monitored. If the absolutevalue of the zero-sequence voltage change vector (ΔU) exceeds a predeterminedthreshold value, the line-to-neutral voltages (U) are compared to the zero-sequencevoltage change vector (ΔU) in the context of a change in the state of the network.According to an advantageous embodiment, the phase is interpreted as being faultedwhose line-to-neutral voltage is ahead of the zero-sequence voltage change vector ΔUby approximately 90°. The fault resistance can be computed from the variables obtainedindependently for each sending end supplied by the electric station.
申请人:ABB Substation Automation Oy
地址:P.O. Box 699 65101 Vaasa FI
国籍:FI
代理机构:Lipsanen, Jari
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