In this paper structure of a expert program which is called HAPP is detailed . The program is designed and developed for alarm processing and fault diagnosis of twelfth – pulsed HVDC network.
The developed program has been designed with artificial intelligent program language (PROLOG ) . HAPP by analysis of variety and distributed information that recieves from different parts of a HVIDC system like breakers status and system parameter quantities in addition to, detect important alarms and fault diagnosis , it could observe and test misoperation of equipments followed by any fault occurance If HAPP observes any lack of coordination of accessory equipments , it will show the problem on a computer monitor.