Research on protective relaying systems based on multi-agent system

Improving selectivity, celerity, sensitivity and reliability is the purpose of research in protection. Although principles and performance of protective relaying have been improved, their operation is still unsatisfied, due to the difficulty in cooperation work. As a branch of distributed artificial intelligence (DAI), agent technology has become a hot spot and researches have been done. But the coordination and collaboration of protection has not been well considered in those works. In this paper, agent technology and the up-to-date research works on its application in protection systems are reviewed. The application of agent in protection system is considered in details from three different hierarchies. Then a protection system based on multi-agent system (MAS) is proposed. The characteristics, structure, classification and decision-making process of this system is elaborated. Served as example, two designs are outlined. One is backup over-current relaying for a power line, the other is a grounding fault detector for a substation. Using the Alternative Transients Program (ATP) as the simulation tool, these systems are simulated. The result shows that through the coordination among distributed protection agents, the process of relay tripping and fault detection can be accelerated and the accuracy of grounding fault detection can be improved. Through cooperation and consideration of protection agents based on different principles, the system's ability of fault-tolerance can be enhanced. Consequently trip failure and malfunction can be avoid effectively and the time for operation can be curtailed effectively. Compared with a conventional protection system, its performance is more satisfactory.