In this paper, a new noncommunication-based
scheme is presented for the protection of three-terminal transmission
lines. Using this scheme, simultaneous operation of circuit
breakers (CBs) at all terminals is provided for all internal faults.
This scheme can discriminate between external and internal faults
based on initiated transients by faults, considering the high-stop
filtering property of busbars through modeling their stray capacitances
and employing a newly defined mathematical morphology
(MM) filter to analyze the captured transients. Moreover, the
transients generated by lightning or switching are identified and
prohibited to enter the algorithm. The presented scheme has been
applied on one of three-terminal lines in Iran’s Transmission Grid.
The effects of fault resistance, fault inception angle, (internal)
fault location, and fault type on the performance of the proposed
scheme are evaluated, where the high dependability, accuracy,
and speed are verified.
Index Terms—Mathematical morphology (MM), noncommunication,
protection, three-terminal transmission line, transient
based.