Integrating a Wave Farm into an Isolated Power System with Energy Storage Systems: Analysis of Frequency Stability and Renewable Energy Penetration

Abstract

Integrating non-dispatchable renewable energy sources (RES), such as wind, solar or wave farms (WF), into isolated power systems poses significant challenges due to their variability and limited predictability. This issue is particularly critical for islands like El Hierro (Canary Islands, Spain), where there is no interconnection with larger grids. Although wave energy offers substantial potential, assessing the maximum feasible RES penetration while maintaining system stability remains complex. This study analyses frequency deviations in an islanded power system integrating a wave farm supported by an energy storage system (ESS). Frequency restoration is managed using droop control, where ESS power output responds proportionally to frequency deviations. The impact of varying wave energy penetration levels and droop control parameters on the system is analysed. The simulation environment is built in MATLAB Simulink, incorporating a dynamic model of the electrical system, which includes wind power, a pumped-storage hydroelectric plant, and diesel generators. WF model is developed based on local wave resource data, simulating power output and variability. The Spanish Grid Code is used to assess regulatory compliance. Results identify optimal droop control parameters for each wave farm size, ensuring frequency deviations remain within acceptable limits. Additionally, the minimum required ESS capacity is estimated for stable operation under different scenarios. These insights support this methodology for effective dimensioning of wave farms and storage systems in isolated grids, enabling higher RES integration while preserving system reliability.