**5. Conclusions**

An isolated WDPS with a DL and a LS-FESS was modelled using the Matlab–Simulink framework in Section 2. Section 3 presented, analysed (using Equation (8)) and simulated the WTG power excess scenario in the DL and FESS-o ff case giving a solution which guarantees power supply continuity with a practical engineering view. Section 4.1 analysed (using Equation (9)) how to guarantee the WDPS absolute stability by using the DL/FESS, and Equation (10) made use of the power supply capability of the FESS to additionally perform frequency support. Section 4.2 presented the simulations for the only-DL and only-FESS cases, showing that both DL and FESS cases prevent the DE reverse power and system frequency increase and therefore it is not necessary to trip the WTG CB unlike the DL and FESS-o ff case. Table 1 summarized that both DL and FESS cases improve the WDPS power quality by avoiding the strong frequency and voltage perturbations existing in the DL and FESS-o ff case. Additionally, Figures 7–10 and Table 1 show that the frequency support of the only-FESS case results in lower variations and oscillations in the WDPS frequency and voltage amplitude than the only-DL case. The reason for the better performance of the FESS is the use of its fast action PWM converter with high bandwidth and high resolution instead of the connection of the discrete value resistors at the zero crossing performed by the DL with limited bandwidth.

Further research will include simplifying the dump load by making use of the higher energy density of the last generation FESS [32].

**Author Contributions:** Conceptualization, R.S.; methodology, R.S., R.P.-A.; software, R.P.-A.; validation, R.S.; investigation, R.S., R.P.-A.; writing—original draft preparation, R.S.; writing—review and editing, R.S., R.P.-A.; visualization, R.S.; supervision, R.S.; project administration, R.S.; All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding

**Conflicts of Interest:** The authors declare no conflict of interest.
