Robust Multi-stage Power Grid Operations with Energy Storage

The uncertainty and variability of renewable generation pose significant challenges to reliable power-grid operations. This paper designs robust online strategies for jointly operating energy storage units and fossil-fuel generators to achieve provably reliable grid operations at all times under high renewable uncertainty, without the need of renewable curtailment. In particular, we jointly consider two power system operations, namely day ahead reliability assessment commitment (RAC) and real-time dispatch. We first extend the concept of "safe-dispatch sets" to our setting. While finding such safe-dispatch sets and checking their non-emptiness provide crucial answers to both RAC and real-time dispatch, their computation incurs high complexity in general. To develop computationally-efficient solutions, we first study a single-bus case with one generator-storage pair, where we derive necessary conditions and sufficient conditions for the safe-dispatch sets. Our results reveal fundamental trade-offs between storage capacity and generator ramp-up/-down limits to ensure grid reliability. Then, for the more general multi bus scenario, we split the net-demand among virtual generator-storage pairs (VGSPs) and apply our single-bus decision strategy to each VGSP. Simulation results on an IEEE 30-bus system show that, compared with state-of-art solutions, our scheme requires significantly less storage to ensure reliable grid operation without any renewable curtailment.