Hydrogen energy storage (HES) has attracted renewed interest as a means to enhance the flexibility of power balancing to achieve the goal of a low-carbon grid. This paper presents an innovative data-driven HES model that reflects the interactive operations of an electrolyzer, a fuel cell, and hydrogen tanks. A model predictive control strategy is then developed, in which HES units support the frequency regulation (FR) of a microgrid (MG). In the proposed strategy, an MG-level controller is designed to optimize power sharing, to allow the HES units to respond quickly to power supply-and-demand imbalances, while distributed generators compensate for any remaining imbalance. The MG-level controller cooperates with the HES-level controllers, which change the operating modes and override the FR supports based on the hydrogen levels. Small-signal analysis is conducted to evaluate the contribution and sensitivity of the FR supports. Comparative case studies are also carried out, wherein HES model accuracy is verified and a hardware-in-the-loop simulation is implemented. The results of the small-signal analysis and case studies confirm that the proposed strategy is effective for reducing frequency deviations under various MG conditions, characterized by the net load demand, line congestion, plug-and-play, model parameters, and communication time delays.

A microgrid energy management system (MEMS) optimally schedules the operation of dispatchable distributed energy resources to minimize the operation costs of microgrids (MGs) via an economic dispatch (ED). Actual ED implementation in the MEMS relies on an optimization software package called an optimization solver. This paper presents a comparative study of optimization solvers to investigate their suitability for ED implementation in the MEMS. Four optimization solvers, including commercial as well as open-source-based ones, were compared in terms of their computational capability and optimization results for ED. Two-stage scheduling was applied for the ED strategy, whereby a mixed-integer programming problem was solved to yield the optimal operation schedule of battery-based energy storage systems. In the first stage, the optimal schedule is identified one day before the operating day; in the second stage, the optimal schedule is updated every 5 min during actual operation to compensate for operational uncertainties. A modularized programming strategy was also introduced to allow for a comparison between the optimization solvers and efficient writing of codes. Comparative simulation case studies were conducted on three test-bed MGs to evaluate the optimization results and computation times of the compared optimization solvers.

Hydrogen energy storage (HES) systems have recently received attention due to their potential to support real-time power balancing in a power grid. This paper proposes a data-driven model predictive control (MPC) strategy for HES systems in coordination with distributed generators (DGs) in an islanded microgrid (MG). In the proposed strategy, a data-driven model of the HES system is developed to reflect interactive operations of an electrolyzer, hydrogen tank, and fuel cell, and hence the optimal power sharing with DGs is achieved to support real-time grid frequency regulation (FR). The MG-level controller cooperates with a device-level controller of the HES system that overrides the FR support based on the level of hydrogen. Small-signal analysis is used to evaluate the contribution of FR support. Simulation case studies are also carried out to verify the accuracy of the data-driven model and the proposed strategy is effective for improving the real-time MG frequency regulation compared with the conventional PI-based strategy.