A PROPOSED AUTOMATIC LOAD SHEDDING SCHEME FOR AN OFFSHORE PLATFORM

The mainobjective of this project is to design an automatic load shedding scheme for
an offshore platform (Bekok-C) to halt power failure and total system collapse. The
scope of study consists of system analysis that proposes the best approach in doing
load shedding, system's calculation and development of Graphical User Interface
(GUI) of proposed automatic loadshedding scheme using software.
There are two main techniques in doing load sheddingwhich are underfrequency and
undervoltage load shedding scheme. Undeniably, underfrequency load shedding is
more popular rather than undervoltage due to its efficiency. As total loss of
generation occurs within a system, the first indicators are drops in voltage and in
frequency, butunfortunately, the voltage drops canalso be caused by system faults. It
is recognized, that a drop in frequency is a more reliable indication of loss of
generation. Asudden lossof generation will result in a reduction in the frequency at a
rate of change which depends on the size of the resultant overload and the inertia
constant ofthe system.
Under this proposed load shedding scheme, as frequency falls below preset level at
certain rate, a predetermined amount of load will be removed to restore the system
frequency. Important design considerations of this scheme are maximum anticipated
overload, number of load shedding steps, size of load shed at each step and frequency
relay settings. Then, load restoration can only be executed either manually or
automatically after the system has recovered completely and its normal frequency is
restored. Loads will be restored in small blocks sequenced by time delay between
successive restorations to allow frequency stabilization.