Robust Control of Power Buffers in DC Microgrids

Power buffers are dc-dc converters with large capacitors to provide inertia during microgrid transients. This power buffer converter precedes the point-of-load (PoL) converter; the later converter is tasked with regulating the load voltage. By controlling the input impedance of the power buffer, the impact of abrupt load changes on the resistive dc network is cushioned. In practice, dc microgrids might need to support uncertain loads. Such loads, however, have not been treated for power buffers with proper robust controllers. Herein, load uncertainties are represented using polytopic models, and state feedback controllers are developed by solving the resulting linear matrix inequalities. Centralized, decentralized, and distributed control schemes are accommodated in the presence of uncertain loads. Proposed robust controllers are validated for a dc microgrid, populated with power buffers, in a controller/hardware-in-the-loop environment.