Multi-Stage Robust Optimization of a Wastewater Treatment Biogas Generator Participating in Day-Ahead and Real-Time Regulation Markets

Wastewater treatment plants are large, energy-intensive loads that can be optimally controlled to support grid reliability and reduce operational costs. This paper presents a multi-stage robust optimization framework to control a wastewater treatment plant equipped with a biogas generator and storage tank for participation in California’s day-ahead and real-time frequency regulation markets while managing biogas production and regulation signal uncertainty. We solve for day-ahead regulation capacity in the first stage and real-time regulation capacity over the day as the uncertainty is progressively revealed. We propose affine control policies to determine the real-time regulation capacity based on partial uncertainty realizations. This results in a tractable affinely adjustable robust counterpart. In a case study, we evaluate our proposed approach against a day-ahead-only robust formulation and found that our approach increases regulation capacity provision and lowers operational costs.