الفهرس 
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Abstract
Over the last decade different algorithms for co-ordinating the directional overcurrent relays in interconnected power networks have been developed and published in the literature. Among these are break points and linear programming algorithms. In the break point algorithm, the group of relays which break all the simple loops in a meshed power network
, e detemlined using either a linear graph theory method or a functional dependency
oncept. The co-ordination sequence is started by assuming initial setting values for all lays. The set of relays are arranged in a primary/backup pair sequence such that whenever backup relay is set all the associated primary relays have already been set in previous ps. The operating time of the backup relay must lag that of its primary relay by a -ordination time interval. If the difference in operating time of any break point relay and
primary relay is less than the co-ordination time interval, iterations are repeated until this ndition is satisfied. This sequence ensures that each backup relay is visited only once per
thi,s thesis, the method for topological analysis of protection schemes using a functional ndency concept suggested by Jenkins[21] has been modified to be suitable for culating the minimum break point set. A new algorithm for calculating this set is ggested which depends on both graphic theoretical schemes and the functional ndency concept.
problem of co-ordinating the directional overcurrent relays in an interconnected power em has been formulated as a linear programming problem. The objective function is to . ise the sum of the operating times of primary relays, subject to the constraint that the rating time for each backup relay should lag the corresponding primary relay by a certain ordination time interval. This optimisation is carried out for different fault locations
ing to the calculation of optimum time dial settings.
, three algorithms have been suggested for co-ordinating the directional overcurrent ays in an interconnected power network using the linear programming technique. These orithms are as follows: the dual revised simplex algorithm of linear programming, nders algorithm of linear programming, a parallel processing algorithm based on the faction balance principle of linear programming.