1. A system for determining a generator dispatch plan for a power grid under uncertain conditions comprising: a memory storage device; a processor coupled to the memory device, the processor configured to: receive data modeling power flow of active generation units over nodes of a power grid network of multiple local buses interconnected via alternating current transmission lines, said active generation units including conventional energy generators producing energy; receive during a first time interval data of a set of forecast scenario modeling uncertainty in renewable energy output, said set capturing a finite number of scenarios generation for an immediately successive 2nd time interval; formulate a nonconvex optimization problem modeling an economic dispatch problem under renewable-generation uncertainty using said finite number of scenarios; solve said nonconvex optimization problem during said first time interval to obtain power dispatch levels for said generators and energy levels exchanging with a spot market for each scenario at said immediately successive 2nd time interval that minimizes expected cost of power generation and cost of exchanging energy with a spot market modeled for each said modeled uncertainty, wherein to solve said nonconvex optimization problem includes solving a two-stage minimization problem by: decomposing said non-convex optimization problem based on an iterative outer approximation technique, said decomposing including solving a sequence of lower-approximation problems for a first-stage minimization problem with each iteration improving a piecewise-linear outer-approximation for a recourse function that represents the second time interval stage costs of the spot market access.