Both renewable energy and nuclear energy are expected to be increasingly and rapidly integrated into future electricity systems in some countries; however, there are still many bottlenecks for their penetration from technological and systematic perspectives. On the other hand, one of the most crucial elements of future electricity systems will be the capability for smart controls on both the supply and demand sides to perform under real-time dynamics. Therefore, a methodology was proposed in the present study to analyze the penetration of renewable and nuclear energy into future electricity systems with new added electric devices such as batteries, electric vehicles and heat pumps operated under smart control strategies. The methodology was based on a set of models organized into an inputoutput framework and actualized using an hour-by-hour computer simulation to achieve a real-time supplydemand balance. The methodology has been developed as a flexible software platform and applied to the Kansai area in Japan. The interactions between the integration of renewable and nuclear energy and operation patterns of new controllable devices were obtained and compared in different scenarios. The feasibility of the proposed methodology has been demonstrated through the scenario analysis. Copyright (c) 2012 John Wiley & Sons, Ltd.