Simulation of an Islanded DC Microgrid Using Instantaneous and Average Modeling Approaches

With the proliferation of renewable energy sources and the adoption of several policies to reduce environmental risks caused by traditional polluting sources, the concept of microgrids, especially DC microgrids, is currently gaining interest. In fact, most renewable energy sources (RESs) and loads are inherently DC type. Moreover, DC microgrids offer many merits over AC ones in terms of ease of control and efficiency. While most of researches address the control hierarchy and strategy in DC microgrids, this paper focuses on the modeling and simulation aspect. A typical configuration of an islanded DC microgrid is modeled in MATLAB/Simulink, and a primary-level control strategy is adopted where two approaches of converters modeling are tested: instantaneous and average model. The two approaches of modeling are compared in terms of precision of losses modeling, dynamic response of the system, simulation time, and computational burden. Simulation tests are conducted, and the results show that, despite its accuracy, the instantaneous model can be applied only for short-term simulations due to many limitations, whereas average converter modeling presents a better solution for long-time simulations, since it ensures a tradeoff between model accuracy and simulation time, which makes the application of the three levels of hierarchical control in DC Microgrids valid in one simulation model

Pathways to the Next-Generation Power System with Inverter-Based Resources: Challenges and recommendations

Managing the stability of today's electric power systems is based on decades of experience with the physical properties and control responses of large synchronous generators. Today's electric power systems are rapidly transitioning toward having an increasing proportion of generation from nontraditional sources, such as wind and solar (among others), as well as energy storage devices, such as batteries. In addition to the variable nature of many renewable generation sources (because of the weather-driven nature of their fuel supply), these newer sources vary in size - from residential-scale rooftop systems to utility-scale power plants - and they are interconnected throughout the electric grid, both from within the distribution system and directly to the high-voltage transmission system. Most important for our purposes, many of these new resources are connected to the power system through power electronic inverters. Collectively, we refer to these sources as inverter-based resources