  Uncertainty in renewable energy generation and load consumption is a great
challenge for microgrid operation, especially in islanded mode as the microgrid
may be small in size and has limited flexible resources. In this paper, a
multi-timescale, two-stage robust unit commitment and economic dispatch model
is proposed to optimize the microgrid operation. The first stage is a
combination of day-ahead hourly and real-time sub-hourly model, which means the
day-ahead dispatch result must also satisfy the real-time condition at the same
time. The second stage is to verify the feasibility of the day-ahead dispatch
result in worst-case condition considering high-level uncertainty in renewable
energy dispatch and load consumptions. In the proposed model, battery energy
storage system (BESS) and solar PV units are integrated as a combined
solar-storage system. The BESS plays an essential role to balance the variable
output of solar PV units, which keeps the combined solar-storage system output
unchanged on an hourly basis. In this way, it largely neutralizes the impact of
solar uncertainty and makes the microgrid operation grid friendly. Furthermore,
in order to enhance the flexibility and resilience of the microgrid, both BESS
and thermal units provide regulating reserve to manage solar and load
uncertainty. The model has been tested in a controlled hardware in loop (CHIL)
environment for the Bronzeville Community Microgrid system in Chicago. The
simulation results show that the proposed model works effectively in managing
the uncertainty in solar PV and load and can provide a flexible dispatch in
both grid-connected and islanded modes.
