Power and Energy Engineering

Most of renewable energy has to use inverters to supply their power to the conventional grid; that is a huge synchronous system, composed of numerous numbers of synchronous generators. Inverters do not have a synchronizing mechanism. Therefore, it is said that penetration of renewables will be limited. Digital Grid is a new concept of multiple electrical grids (called “cell”), connecting each other asynchronously. In the cell grid, we are free from conventional electrical constraints and can create a new type of electric power system. In this paper, we propose GPS synchronized grid system. GPS satellite time signal will make very accurate carrier frequency for the inverters, and then all the inverters in the cell will synchronize very accurately. We can acquire rotating inertia for inverters. Inverters behave as a voltage source, and then the power system in the cell becomes a linear system. Digital Grid will be most promising power system for renewable penetration because we can utilize existing infrastructure with plenty of inverters. We can utilize full of renewable energy in the future.