  The large-scale integration of renewable generation directly affects the
reliability of power grids. We investigate the problem of power balancing in a
general renewable-integrated power grid with storage and flexible loads. We
consider a power grid that is supplied by one conventional generator (CG) and
multiple renewable generators (RGs) each co-located with storage,and is
connected with external markets. An aggregator operates the power grid to
maintain power balance between supply and demand. Aiming at minimizing the
long-term system cost, we first propose a real-time centralized power balancing
solution, taking into account the uncertainty of the renewable generation,
loads, and energy prices. We then provide a distributed implementation
algorithm, significantly reducing both computational burden and communication
overhead. We demonstrate that our proposed algorithm is asymptotically optimal
as the storage capacity increases and the CG ramping constraint loosens.
Moreover, the distributed implementation enjoys a fast convergence rate, and
enables each RG and the aggregator to make their own decisions. Simulation
shows that our proposed algorithm outperforms alternatives and can achieve
near-optimal performance for a wide range of storage capacity.
