For a microgrid (MG) to participate in a real-time and demand-side bidding market, high-level control strategies aiming at optimizing the operation of the MG are necessary. One of the difficulties for research of a competitive MG power market is the absence of efficient computational tools. Although many commercial power system simulators are available, these power system simulators are usually not directly applicable to solve the optimal power dispatch problem for an MG power market and to perform MG power-flow study. This paper analyzes the typical MG market policies and investigates how these policies can be converted in such a way that one can use commercial power system software for MG power market study. The paper also develops a mechanism suitable for the power-flow study of an MG containing inverter-interfaced distributed energy sources. The extensive simulation analyses are conducted for grid-tied and islanded operations of a benchmark MG network.