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The dynamics of a general class of weakly nonlinear oscillators can be used to control power converters to create a self-forming AC network of distributed generators. Many control stability results for these “virtual” oscillators consider the interaction of voltage-source converters, but most practical converters use a nested current loop. This paper develops a general method to extend voltage-source stability results to current-controlled converters using a virtual admittance. A fast current control loop allows a singular perturbations analysis to demonstrate the equivalence of the two. This virtual admittance can also manipulate load sharing between converters without changing the core nonlinear dynamics. In addition, Virtual Oscillator Control is experimentally demonstrated with three-phase voltage-sourced and current-controlled inverters. This validates the equivalence of the two formulations, and extends previous single phase testing into three phases. The extension to current-controlled converters enhances safety and increases the breadth of applications for existing control methods.

Small microgrids can derive their electrical power from a variety of energy resources. Some of these, including U.S. Military Forward Operating Bases (FOBs), use diesel generators as the primary or sole resource. In almost all cases, efficient utilization of generation resources is a high priority. This is particularly so for FOBs, for which diesel fuel resupplies come at remarkable monetary, logistical, and safety costs. Increasing the fuel efficiency of such microgrids requires not only incremental improvements to generation and load services, but also a higherlevel understanding of how these components interact. This study of a typical U.S. Army FOB characterizes its power system, which is powered by diesel generators and has a load profile dominated by distributed environmental control units (ECUs). The study contributes an actionable simulation model of this power system and uses it to identify an opportunity for energy savings through appropriate scheduling of the ECUs.

Significant electrical loads such as HVAC systems can be made ''aware'' of the operation of other loads nearby in the electric grid. Local examination of the utility voltage waveform can provide this awareness without the need for a dedicated communication network. This is particularly true in lowinertia microgrids and ''soft'' sections of a utility network. This paper presents techniques for extracting frequency and voltage harmonic transients corresponding to individual load events. With data collected from a microgrid energized by diesel generators, we demonstrate the ability to identify the operation of HVAC units and generator dispatch events from their transient effects on the voltage using a cross-correlation based scoring algorithm. Ultimately, incorporating such awareness into load controllers allows loads to autonomously meet system-level objectives in addition to their individual requirements. For example, HVAC units could maintain occupant comfort while also reducing the utility's peak aggregate electrical demand by consuming electricity on a schedule interleaved with the operation of other nearby HVAC units.

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