A STUDY OF PROTECTION SYSTEM TO IMPROVE POWER SYSTEM RELIABILITY USING ATP (ALTERNATIVE TRANSIENT PROGRAM)

Electric power systems are one of the largest and more complex systems man has ever
built. Faults represent a threat to the operation and security of power systems if the faults
are not promptly corrected. Therefore protection of the power system is very important.
Protective relays are electronic or electromechanical devices that are designed to protect
equipment and limit injury caused by electrical failures. Protective relays cannot prevent
faults; they can only limit the damage caused by faults. This thesis investigates the
importance of power systems protection and also introduces the widely used power
system software, ATP ( Alternative Transient Program ). Using this software, power
system are modeled and disturbance scenarios such as lightning overvoltages and short
circuit are generated. The simulation of this scenarios provides the graphical
charateristics of the power system through the use of PLOTXY function. Another major
work in this project is the modeling of relays that were embeded in the system to enable
classed loop simulation whereby the relay will provide a 'feedback' to the system. The
'feedback' is a trip signal which will be sent to the circuit breaker to open or reclose. The
algorithm of the relay are designed by writing specific code using the MODELS
language. The relays succesfully fuctioned according to the algorithm when simulated
under different disturbance scenarios and the results obtained were same as the predicted
output.