Grid Modernization Act This bill requires the Department of Energy (DOE) to conduct a program to modernize the electric grid, including by (1) developing standards to compare the storage capacity, cycle length, capabilities, and reliability of different types of electricity storage; (2) promoting the development of micro-grid systems; (3) facilitating a collaborative process to develop model grid architecture; and (4) ensuring a reliable, resilient, affordable, safe, and secure electric grid. (A micro-grid system means a stand-alone electrical system that uses grid-scale energy storage.) DOE must also establish a grant program to carry out projects related to the modernization of the electric grid, including the application of technologies to improve observability, advanced controls, and prediction of system performance on the distribution system.