Protective relay device for DC transmission system

摘要

PROBLEM TO BE SOLVED: To diminish the anxiety of malfunctioning of a relay caused by error, to set the sensitivity of the relay higher, and to protect the feeder line. SOLUTION: A protective relay device, which detects currents flowing in both ends of the feeder of a DC transmission system transmits the currents between the mutual sites to each other, and protects a feeder line 7 from a trouble, is provided with a settling means 13-6, which settles references for specified processing and judgment necessary for operation, a transmitting means 13-3 which transmits a current led in from a direct current transformer 8a to the other party end, a second computing means 13-4 computes a difference current being the sum of a current to be led in and the current from the other party end taken in from the transmitting means, computes variation components of the difference current from the difference between that computed difference current and a difference current found at time past by a time interval inputted from the settling means 13-6 and reduced error components, and judges that trouble occurs in the feeder line 7, when the variation component satisfies prescribed relation to a reference value inputted from the settling means, and an output means 13-5 which outputs the result of this judgment.