With the expansion of renewable energy and the liberalization of the electricity market , the complexity and uncertainty of the future power system and market are increasing and it is required to provide high-value products and services to mitigate them and to contribute the realization of a decarbonized society. We use simulation technology for power supply operation to forecast the operating schedule of each generator and the electric power price to minimize total social cost under future scenarios of power demand, capacity mix, etc. while considering the constraints of the transmission system. This report explains an overview of this technology and the original evaluation framework of Mitsubishi Heavy Industries, Ltd. (MHI) for the improvement of our products and services, while also giving application examples.