Title :
A fresh look at limits to the sensitivity of line protection
Author :
Schweitzer, Edmund O., III ; Fischer, Normann ; Kasztenny, Bogdan
Abstract :
This paper considers the sensitivity of essential line protection elements: ground distance and ground directional overcurrent elements applied as time-coordinated functions or in pilot-assisted protection schemes and line current differential schemes. Factors discussed include fault resistance, line unbalance and charging currents, impact of in-line reactors, system short-circuit capacity, load encroachment and swings, sequential tripping and weak feed terminals, steady-state and transient errors of instrument transformers, impact of current transformers (CTs) in dual-breaker line terminals, and single-pole-open conditions. Protection element design improvements and application principles enhancing sensitivity are included.
Keywords :
current transformers; earthing; instrument transformers; overcurrent protection; power transmission lines; power transmission protection; CT; charging current; current transformer; dual-breaker line terminal; fault resistance; ground directional overcurrent element; ground distance overcurrent element; in-line reactor impact; instrument transformer; line current differential scheme; line protection sensitivity; line unbalance; load encroachment; pilot-assisted protection scheme; protection element design improvement; sequential tripping; short-circuit capacity system; single-pole-open condition; steady-state error; time-coordinated function; transient error; weak feed terminal; Circuit faults; Current measurement; Grounding; Impedance; Instrument transformers; Security; Sensitivity;
Conference_Titel :
Protective Relay Engineers, 2011 64th Annual Conference for
Conference_Location :
College Station, TX
Print_ISBN :
978-1-4577-0494-9
DOI :
10.1109/CPRE.2011.6035604
