الفهرس 
STUDY OF THE SYSTEM STABILITY USING THE EQUAL AREA CRITERIONOnly 14 pages are availabe for public view
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Abstract
Research work in the area of power system stability is an important
task for electrical power engineers. The power system stability problem
may be defined as the main problem that accompanied the growth,
development, and complex interconnection of power system. The solution
~~ of the problem has been tried out in several directions. Static excitation
systems, fast acting automatic voltage regulators, power system stabilizers
and even fast controllers or the governor system represented on direction
related to the unit level. On the station or area level the local control room
with facility on load sharing and load shedding acted as a second
direction. The third and the most important is the dispatch among areas on
bases of economics or any other consideration.
Although modem power systems are complex and may be composed
of a large number of generators, the two machine system still represent a
challenging problem for the investigation of this system stability. A twomachine
system can in conclusion represent a full and large power system
such as Egypt’s system. This system can be looked as two-machine
system with a long transmission line connected in-between. The thermal
power plants in the north and the hydro-electric plants in the south lend
them as the two machines with 500 kv line as connectors.
The present work investigates the stability problem with two main
aims. The first goal is obtaining a fast approximate system of monitoring
system transient stability based on the classic equal area criterion. The
system parameters in this case required for computation are minimum and
so is the computational time. The results of this part are used as an early
alarm data telling operators whether the system will be inherently stable
or may be driven into a critical stability problem. There are different
methods have been suggested to improve the system transient stability
such as forced excitation, fast switching, increased inertia and fast valving
methods.
The second goal is study the system dynamic stability using
different types of the power system stabilizers. The conventional power
system stabilizer is designed only for a specific operating point. The
artificial neural network (ANN) power system stabilizer overcomes this
difficulty and successfully used in many other applications.This thesis presents an efficient on-line ANN-based power system stabilizer
of the power system. The on-line training technique is used to update the
weights and biases of the ANN using the on-line back propagation algorithm.
The ANN control technique is used to enhance the power system to avoid the
system oscillation when it is subjected to different disturbances. Meanwhile the
ANN-PSS is compared with the conventional PSS to demonstrate the
advantages of the proposed ANN. The effect of changing the learning rate, the slopes of the linear activation function of the output layer and the number of
the neurons in the hidden layer on the dynamic response of the single machine
to infinite bus power system are demonstrated.
A novel configurations of the ANN driven by a variable learning rate and
another configuration of the ANN driven by a variable slope of the linear
activation function of the output layer are introduced in order to obtain the best
dynamic performance of the single machine to infinite bus disturbed system.
The two-machine system under study consists of two synchronous generators
each equipped with AVR and PSS. The system is SUbjected to different
disturbances on each machine termin al, also the PSS of each machine may be
conventional or ANN-based. The proposed ANN-PSS of the disturbed machine
takes larger control action than the ANN-PSS of the second machine.
The effect of changing the learning rate and the slopes of the linear activation
function of the output layer in the ANN-PSSs of the two machines are
demonstrated.