Transient Response of Generator- and Inverter-Based Microgrids to Rapid Load Changes

Electromagnetic compatibility (EMC) challenges arise in generator and inverter-based power supplies due to the presence of inrush currents and rapid load changes among other electromagnetic interference sources. Inrush currents and rapid load variations have shown to cause EMC issues in the form of poor power quality. In this article, the fundamental principle of elements containing the energy are discussed where energy of rotational inertia is compared to electrical energy stored in capacitors and inductors. The investigated microgrids which include a mobile generator (rotational energy) powered military ground vehicle and an off-grid inverter (electrical energy) are measured and analyzed with respect to rapid load changes. This will identify challenges and inherent difference between generator based inverter based microgrids, as well as the benefits of each with respect to different load characteristics. This lays a foundation of determining the optimum between the quality of supply and the quality of demand, where inertia is a key factor in stability. The primary conclusion drawn from the measurement and analysis underscores the significance of load rising edge and amplitude in resulting instability due to transient load fluctuations. Measurements from real world applications show $\pm$12-13% voltage deviations for a generator based system and up to 20% for a inverter based system on a rapid load change event.