High penetration of renewable energy sources into isolated microgrids (µGs) is considered a critical challenge, as µGs’ operation at low inertia results in frequency stability problems. To solve this challenge, virtual inertia control based on an energy storage system is applied to enhance the inertia and damping properties of the µG. On the other hand, utilization of a phase-locked loop (PLL) is indispensable for measuring system frequency; however, its dynamics, such as measurement delay and noise generation, cause extra deterioration of frequency stability. In this paper, to improve µG frequency stability and minimize the impact of PLL dynamics, a new optimal frequency control technique is proposed. A whale optimization algorithm is used to enhance the virtual inertia control loop by optimizing the parameters of the virtual inertia controller with consideration of PLL dynamics and the uncertainties of system inertia. The proposed controller has been validated through comparisons with an optimized virtual inertia PI controller which is tuned utilizing MATLAB internal model control methodology and with $H_{\infty }$-based virtual inertia control. The results show the effectiveness of the proposed controller against different operating conditions and system disturbances and uncertainties.

Supplying electric energy in remote areas presents a significant challenge due to their relatively far distance from the main grid, low population density, high infrastructure costs, and limited resource. One promising solution to this challenge is the isolated hybrid microgrids (MGs) which can deliver reliable electricity and support economic development. The current work introduces an optimal design of isolated hybrid MGs for remote areas, whereas, a small Nubian village in Aswan, Egypt (a desert climate region) is taken as a case study. The study mainly relies on techno-economic and environmental analyses for different microgrid configurations. The analysis has been carried out utilizing Hybrid Optimization Model for Electric Renewable (HOMER Pro software) to find the least-cost design among hundreds of alternatives based on the weather conditions in this area. Recently, incorporating the renewable energy sources (RES) into local power networks is among the most prominent research areas. Although many typical components can be used to develop the required microgrid system, there are also many limitations on these components, such as resources availability and costs. Several photovoltaic (PV) /wind/diesel/storage Hybrid Energy Systems (HES) have been studied in this paper. Additionally, the effectiveness of a mechanical PV tracking system and impact of battery technologies, such as lead-acid and lithium-ion on the overall costs of the energy system has been discussed. The proposed analysis shows that the PV-wind-lithium-ion battery energy system with vertical-axis PV tracking system is the most economical option, which attains a Net Present Cost (NPC) of $853,634.53 and a cost of energy (COE) of $0.255 and produces acceptable environmental gas emissions of 64018.15 kg/yr. Besides, a 7 years payback of the proposed microgrid system (25-years-lifetime) has been attained.

International Journal of Electrical Energy (IJOEE)