Single phase lockout on a single long line connecting two power systems with particular reference to the Nairobi-Mombasa power transmission line.
Abstract
The possibility of operating a single long H.T. Power
transmission line with one phase locked out after a single phase
to ground fault occurs on that phase is investigated. Particular
reference is made to the Nairobi-Mombasa line.
Computer programmes for the solution of asymmetrical faults
at more than one location are developed and used to calculate the
sequence currents and voltages on the system, plus the power
transmission on the lines, with the lockout. Finally the
stability of the overall system with the lockout is investigated.
The results indicate that for a single phase to ground
fault in the middle of the Nairobi-Mombasa line:-
(i) Up to 55% of the prefault power can be transmitted on
the faulted line. The power transmission on the other
lines is not greatly affected.
(ii) Sequence currents on the system excep-t.on the faulted line are within reasonable values - that is none of the
lines, transformers, o~ generators are overloaded.
(ii,i) The system remains stable for a prefault power transfer
of 30 MW along the line in either direction.
(iv) There is a general rise of Bus voltages~ in some cases
of as much as 10%.
Therefore it is concluded that~ the Nairobi-Mombasa
H.T. transmission line can be operated on a single phase lockout
for a limited period when a single phase to ground fault occurs
on the line. This conclusion can be extended to cover cases
where two major load centres located far apart and connected
by a single H.T. line. This has very important implications~
since it means that the two load centres can continue to
exchange power with a single phase to ground fault condition
present. This gives the systems operators time to take
appropriate control actions at the two ends
Citation
Master of Science in EngineeringSponsorhip
University of NairobiPublisher
s