Storage in Risk Limiting Dispatch: Control and approximation

Integrating energy storage into the grid in scenarios with high penetration of renewable resources remains a significant challenge. Recently, Risk Limiting Dispatch (RLD) was proposed as a mechanism that utilizes information and market recourse to reduce reserve capacity requirements, emissions and other system operator objectives. Among other benefits, it included a set of simplified rules that can be readily utilized in existing system operator dispatch systems to provide reliable and computationally efficient decisions. RLD implements stochastic loss of load control to absorb the increased uncertainty in the grid. Storage is emerging as an alternative to mitigate the uncertainty in the grid. This paper extends the RLD framework to incorporate intrahour storage. It develops a closed form scheduling rule for optimal stochastic dispatch that incorporates a sequence of markets and real-time information. Simple approximations to the optimal rule that can be easily implemented in existing dispatch systems are proposed and evaluated. The approximation relies on continuous-time approximations of solutions for a discrete time optimal control problem. Numerical experiments are conducted to illustrate the proposed procedures.