  The increasing penetration of Renewable Energy Sources (RES) requires more
Flexibility Resources (FR), generally thermal units and storages, must be kept
in the system to accommodate the uncertainties from RES. The challenge is how
the system can survive when the RES level is very high. In this paper, RESs are
considered as full-role market participants. They can bid in the day-ahead
market, and the powers they deliver to the market are controllable up to their
maximum available powers. Therefore, RESs are effectively dispatchable and can
function as FR providers. To integrate dispatchable renewables, a two-stage
robust Unit Commitment (UC) and dispatch model is established. In the first
stage, a base UC and dispatch is determined. In the second stage, all FRs
including RESs are used to accommodate the uncertainties, which is a
Mixed-Integer Programming (MIP) problem. It is proved that the solution to the
max-min problem can be identified directly whether the strong duality holds or
not for the inner minimization problem. The solution robustness is guaranteed
by including only one extra scenario. Numerical results show the effectiveness
of the proposed model and its advantages over the traditional robust UC model
with high level RES penetration.
