This report presents a case study promoting digital transformation (DX) for the purpose of stable plant operation and reduction of power generation costs. Mitsubishi Heavy Industries, Ltd. provides our customers with support for realizing stable operation of plant facilities and passing on skilled technologies to reduce the burden related to the operation, through offering applications we developed as the basis for remote monitoring, such as abnormality detection and plant performance diagnosis. In particular, introducing the fuel allocation optimization application and other applications for the first time to customers of ours using multiple units that we delivered was a DX promotion activity that reflected the operation and constraint information of the power plant obtained from the customers. We will continue to propose to our customers an eco-system in which machine systems cooperate by "Smart Connections" of a wide variety of machine products utilizing digital technology.