Coordinated control of HTSE and microgrid for improved capacity factor and grid support

This paper presents a novel two-stage control and optimization methodology for coordinating high-temperature steam electrolysis (HTSE) systems within a microgrid (MG) to enhance both ancillary service provision and HTSE capacity factor. In the first stage, optimal Volt–VAr/Watt droop control parameters are designed for the battery energy storage system (BESS), Volt–VAr droop for the photovoltaic (PV) system, and a novel Volt–Watt droop for the HTSE, all in compliance with IEEE 1547–2018 standards. This stage incorporates the practical operational constraints of the HTSE, PV, and BESS, thereby enabling decentralized ancillary service contributions from each subsystem. Economic optimization of the HTSE can also be prioritized to maximize hydrogen production and capacity factor. The second stage introduces a multiobjective optimization framework that determines high-resolution setpoints for active–reactive power dispatch of the BESS, reactive power generation from the PV system, and active power demand of the HTSE. These setpoints are constrained by the droop control laws derived in the first stage. The BESS is specifically dispatched to compensate for the inherently slow dynamic response of the HTSE, ensuring reliable ancillary service delivery. Uncertainty in PV power generation is also explicitly considered. The proposed formulation is implemented in MATLAB and integrated via Modbus TCP with a real MG comprising a 1 MWh BESS, 1 MW facility load, 1 MW HTSE, and a 2 MW PV array, modeled on a real-time digital simulation (RTDS) platform at the Idaho National Laboratory (INL). Numerical simulations under both grid-connected and islanded operating modes validate the effectiveness and flexibility of the proposed control and optimization strategy.