Analytical Modeling and Control of Grid-Scale Alkaline Electrolyzer Plant for Frequency Support in Wind-Dominated Electricity-Hydrogen Systems

Abstract

Integration of the hydrogen sector into power systems via electrolyzers could greatly facilitate energy sustainability by producing green hydrogen, moreover, assist in reinforcing frequency stability based on optimal control of electrolyzers. In order to improve the frequency performance of the wind-dominated electricity-hydrogen systems (WEHS), this paper investigates how to analytically evaluate and implement the dynamic frequency regulation (DFR) supported by a grid-scale alkaline electrolyzer (AEL) plant. The DFR's potential of the AEL plant is released by an emulated power-frequency characteristic, and its contributions to improving system frequency response are also analytically evaluated from the aspects of transient, steady-state, and stability indicators. Furthermore, the DFR dependency on the frequency containment reserve provision and pre-contingency operating points of AELs are analytically clarified. A DFR-driven controller to coordinate multiple modules in the AEL plant is also designed in detail. In addition, the economic analysis is presented to evaluate the profitability of AELs providing frequency support. Cases of a simple WEHS and a modified IEEE 9-bus system integrated with grid-scale AEL plants during frequency contingencies are studied to validate the proposed DFR method, which can improve the system frequency response with smoother transients and lower steady-state deviation. Index Terms-Alkaline electrolyzer, analytical evaluations of frequency response, grid-scale electrolyzer plant, system frequency support, wind-dominated electricity-hydrogen systems. E

Quantitative Frequency Security Assessment of Modern Power System Considering All the Three Indicators in Primary Frequency Response

“…Frequency security assessments of primary frequency responses are based on the precise system frequency response model [7][8][9]. At present, the simplified mathematical methods for dynamic frequency responses mainly include the Average System Frequency Response Model (ASFR) and the Unified Transfer Function Structure (UTFS) [10][11][12][13][14][15][16][17]. Reference [13] proposes a modified SFR model, which makes a good overall estimation of the frequency.…”

“…Due to the spatiotemporal characteristics of wind turbines and the decoupling parts of power electronic devices, the parameters in the ASFRs of modern power systems cannot be aggregated in the same manner as in a traditional power system [14]. Considering different generations, including wind turbines, references [15,16] propose a frequency response model to analyze a frequency stability-improving method. However, the frequency analytical formula is too complex to describe the dominant frequency stability problem quantitatively and linearly.…”

“…When the frequency drops to fN, corresponding to time tN, |df| has the maximum value, and df/dt has the opposite sign in the right neighborhood. So, when t1 equals tN in (16), Pref(v, wr1) is more significant than Pm(v, wr1) in the neighborhood of time tN. This can help avoid secondary power disturbances effectively.…”

“…When the frequency drops to f N , corresponding to time t N , |df | has the maximum value, and df /dt has the opposite sign in the right neighborhood. So, when t 1 equals t N in (16)…”

Decentralized Dynamic Power Sharing Control for Frequency Regulation Using Hybrid Hydrogen Electrolyzer Systems

“…PEMELs are proposed as the main technology able to provide a fast response for frequency regulation, such as in case of contingencies or to provide Fast Frequency Regulation (FFR) [10]- [14]. For frequency regulation with slower response time, AELs have also been proposed as a solution [15], [16], with lower costs compare to PEMELs [17], [18]. However, it was demonstrated in [16] that large-scale AELs are not suitable in cases where a fast frequency regulation is required.…”