| 摘要 |
<p>High resistance ground faults on a transmission line of an electrical power transmission network are detected with the aid of a device comprising a travelling wave model of the line located in measuring stations (P, Q) at either end of the line, which permits the voltage distribution along the line, seen both from P and from Q, to be obtained. A voltage .DELTA.UQp is formed as the difference between a voltage in station P, calculated in the travelling wave model in Q, and the corresponding voltage one period earlier. A voltage .DELTA.Upp is formed as the difference between a voltage calculated in the travelling wave model at P and the corresponding voltage one period earlier. The corresponding voltage differences .DELTA.Upq and .DELTA.UQq are calculated for station Q. The voltage difference .DELTA.P is then formed as the difference between .DELTA.UQp and .DELTA.UPp, and the corresponding .DELTA.Q is formed as the difference between .DELTA.Upq and .DELTA.UQq. Fault detection is obtained when .DELTA.P > .epsilon.p or when .DELTA.Q > .epsilon.q, where .epsilon.p is the accepted voltage difference at p and .epsilon.q is the corresponding value at Q.</p> |
