MASCEM [1], [2] is a simulation and modeling tool developed to study and simulate electricity market (EM) operation. It models the main market entities and their interactions. Medium/long-term gathering of data and experience is also considered to support players decisions under their specific characteristics and goals. The main market entities are implemented as software agents, such as market and system operators, buyer and seller agents (consumers, producers, and/or prosumers), and aggregators.

The Market Operator regulates pool negotiations by validating and analyzing the player's bids depending on the type of negotiation. It also determines the market price, the accepted and refused bids, and the economical dispatch that will be sent to the System Operator. The System Operator examines the technical feasibility from the power system point of view and solves congestion problems that may arise. It is also responsible for the system's security as well as ensuring that all conditions are met within the system.

The key elements of EM are Buyer and Seller agents. A Buyer agent may be a consumer or distribution company that participates in the market to buy given amounts of power. On the other hand, a Seller agent may simulate electricity producers or other entities allowed to sell energy in the market. Aggregators represent alliances of small independent players to enable their participation in the wholesale market and compete with big players. Aggregators manage their aggregate's information and are seen from the market's point of view as buyer or seller agents.