TROUBLE POINT DETECTION SYSTEM FOR SEARCHING AND PROTECTING TROUBLE POINT OF POWER TRANSMISSION LINE

摘要

PURPOSE:To introduce Laplace transformation for calculation of the distance to a trouble point and to heighten the accuracy of detection of the trouble point, by representing the voltage and current of a point at a distance of (x) from one end of a power transmission line, in relation to the voltage and current of the end of the line and line constants known. CONSTITUTION:The voltage and current of a transmission line 1 are picked out by a PT2, and a CT3. The changes in the voltage and current from the time just after the occurrence of the trouble are determined by a voltage and current change measuring unit 5. Laplace-transformed values e''*(S1), e''*(S2), i''*(S1), i''*(S2) relating to two real numbers S1, S2 are calculated by a Laplace transformation unit 8 on the basis of the measured voltage and current. The effective values of the voltage and current before the occurrence of the trouble are determined by a measuring unit 6. The phase angles thetae*, thetai* of the voltage and current at the time of the detectin of the trouble are determined by another measuring unit 7. The quantities obtained by the measuring units 6, 7 and the transformation unit 8 and a propagation constant gamma, the product mu of the propagation constant and angular frequency and a surge impedance Z, which depend on the line constants of the power transmission line 1 which are previously stored or set, are used to perform calculation and processing on the basis of prescribed fromula in a detection and processing unit 9 to display the distance (x) to the trouble point.