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Abstract
This thesis presents enhanced ultra high speed (UHS) protective
scheme that is based on the travelling wave rrw: technique. It includes
two main fault detection units; the first is analogue for primary protection
and the second is digital for secondary (backup) protection. The two units
are combined in an integrated protective scheme with the appropriate logic.
The algorithm is proposed based on simulation studies that are achieved by
using standard power system simulation software namely electromagnetic
transients including DC (EMTDC). The information contained in the
travelling waves has been used to discriminate between internal and
external faults.
The analogue unit will respond directly after fault inception,
however the digital unit requires analogue-to-digital (AID) conversion in
addition to algorithm processing time and may be delayed by a suitable
backup time. Therefore, the operation of the analogue unit will be faster. It
has a fault detection operating time of 2-3 ms, The final trip decision is to
transmit the trip signal to the output interface if the fault incidence IS
confirmed by the analogue unit or confirmed by the digital unit.
The prototype hardware of the analogue unit was implemented and
tested by a laboratory tests and its performance is found to be accepted.
The algorithm of the digital unit was presented. The performance of
proposed integrated protective scheme for protecting extra high voltage
(EHV) transmission lines has been tested using the simulation data and
confirmed to be satisfactory