| 摘要 |
A method and a device for detecting high resistance ground faults on a power transmission line located between two stations (P, Q), the line being included in a multi-phase distribution or transmission system. The voltage distribution along the transmission line, seen both from station P to station Q and from station Q to station P, is obtained with the aid of a device comprising a travelling wave model of the line located in measure stations (P,Q) at either end of the line. A voltage DELTA UQp is formed as the difference between the voltage in station P, calculated in the travelling wave model in station Q and the corresponding voltage one period/half-period earlier. A voltage DELTA UPp is formed as the difference between the voltage in station P, calculated in the travelling wave model in station P and the corresponding voltage one period/half-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 voltage difference 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 accepted voltage difference at Q. |
