Mhj. Bollen, TRAVELING-WAVE-BASED PROTECTION OF DOUBLE-CIRCUIT LINES, IEE proceedings. Part C. Generation, transmission and distribution, 140(1), 1993, pp. 37-47
Double-circuit current comparison protection (DCCCP) is an algorithm f
or travelling-wave-based protection of a double-circuit high-voltage l
ine. It uses the balance between the two circuits to distingush betwee
n an internal fault and an external disturbance. To prevent incorrect
trips superimposed currents are used, and the relay has to be blocked
after detecting an external disturbance. The setting of relay paramete
rs is discussed, as well as its performance. The tripping time is betw
een 100 and 200 mus for the majority of faults. For faults around volt
age zero, the tripping time is between 1 and 3 ms, depending on the am
plitude of the short-circuit current. Faults close to the remote line
terminal are not detected at all. Some direct lightning strokes will l
ead to an incorrect trip. To overcome the disadvantages of DCCCP, it i
s combined with travelling-wave-based differential protection in a pro
tective scheme. Differential protection is a somewhat slower but very
reliable backup. Its parameter setting is discussed, as well as its pe
rformance. The tripping time is between 1 and 3 ms. The protective sch
eme further contains fast reclosure, breaker-failure detection and ada
ptive setting for the backup relays.