I. Introduction
Agent is an important concept in computer science and distributed artificial intelligence, which represents a new method to conceptualize, describe and implement complex systems. In recent years, the application of Multi-Agent System (MAS) technology in power engineering field has received more and more attention. A range of applications have been developed with this method, including fault diagnostics[1], power market simulation[2], power grid control[3], substation automation [4], voltage control[5], etc. The Intelligent System Subcommittee of IEEE PES has also formed a working group to investigate how the MAS can be used in power system. In 2007, the working group published paper [6] to report their research result. The paper [6] has examined the great potential value of MAS technology to power industry, and also defines some key technical issues which must be addressed before this technology can be successfully employed in the power and energy sector, such as the necessity to develop an effective, reliable and flexible agent platform and a toolkit to reduce complexity in agent development, as well as the issue how agents communicate with each other.