UC Santa Barbara
Virtual Oscillator Controlled Inverters in a Microgrid Setting with Secondary Control and Energy Storage
- Author(s): Bean, Celeste
- Advisor(s): Bullo, Francesco
- et al.
Building from existing work on Virtual Oscillator Control (VOC), this reports details design, analysis, and simulation of a standalone inverter-based microgrid composed of variable renewable energy sources and battery storage. VOC for inverters relies on local voltage and frequency measurements to allow for proportional loading and voltage/frequency synchronization, presenting a real-time decentralized control strategy that mimics droop control characteristics. The design specifications, derivations, models, and simulations demonstrate that VOC can operate bidirectionally (producing and consuming power) for resistive and capacitive loads. The inverters are shown to operate in a variety of more complex settings than have previously been examined: in parallel, under fluctuating loads, and under noisy loads. To compensate for deviations in steady-state frequency and voltage, low-bandwidth communication in the form distributed averaging proportional integral (DAPI) control is adapted, derived, and simulated for a VOC-based microgrid. Lastly, battery models representing distributed Energy Storage Systems (ESS) are incorporated to demonstrate grid robustness in times of excess load relative to generation available.