Achieving Flexible Operation by Aggregating Structured Operating Protocols: An Electrolysis Case Study Using Real Market Data.

Electrochemical devices can play a critical role in providing demand-side flexibility to the power grid, enabling greater integration of renewable power and enhancing system resilience. However, highly dynamic operation that tracks fluctuating market signals can accelerate degradation. To address this challenge, this work proposes a parallel aggregation framework in which multiple device modules operate under predefined structured protocols, defined as stable and periodic operating patterns assigned to individual units. Using a hydrogen electrolysis system participating in the real-time electricity market operated by the Electric Reliability Council of Texas (ERCOT) as a case study, we develop an optimization framework that determines optimal mixing of predefined structured protocols that minimizes total electricity costs. Our results show that the cost of the protocol-based parallel setting closely approximates that of fully flexible operation. This trend is consistently observed across multiple protocol sets and different market days, demonstrating the wide applicability of the proposed concept. The proposed approach can also enhance predictability and practical implementation.