Distributed Assistive Control of Power Buffers in DC Microgrids

Abstract

Low generational inertia and lack of damping elements cause stability concerns in dc microgrids. Power buffers have been introduced to damp volatile load demands and improve microgrid's stability. Power buffer is a power electronics converter with large storage components (e.g., capacitors), which can decouple dynamics of a power distribution network and electronic loads by adjusting its input impedance and stored energy. Typically, power buffers are controlled individually to serve local loads. Alternatively, collective operation of power buffers is considered here to extend their damping effect to neighboring loads. Additionally, the group operation allows buffer designs with smaller storage components. A supervisory control to manage energy-impedance profiles of power buffers across a grid would require a complex communication network. Alternatively, distributed control lays a reliable ground to link power buffers with a minimal communication. This work offers a fully distributed feedback control algorithm to collectively manage the power buffers, using a sparse communication network. The controller enables the buffers to collectively respond to any load transient. Hardware-in-the-Loop simulation of a dc microgrid is used to show the controller's efficacy; it successfully groups power buffers in the neighborhood of the affected load and manages their energy reservoirs to shape the power supplied by the grid.