Recently, several types of distributed energy resources (DERs) have been developed to reduce the environmental impact and support the global demand for electrical energy. However, the continuous penetration of the DERs into modern power systems (MPSs) may cause several adverse impacts in terms of operation performance indices (PIs) and power quality issues, especially in low-voltage distribution systems (LVDSs). To cope with these serious impacts and achieve optimal control, the hosting capacity (HC) of DERs must be accurately estimated and optimally optimized. However, it requires an extensive communication infrastructure, which is hardly offered without clear financial benefits. In this regard, this article investigates the historical developments of HC definitions as well as the recent developments in terms of operational performance indices, and estimation methods for active distribution networks (ADNs) with the high-penetration level existence of the DERs, energy storage systems (ESSs), electric vehicle (EV) charging systems, sector coupling, hydrogen technologies, and multi-carrier energy systems (MESs) to deal with electrical, thermal, and cooling demands. In this regard, this review article is intended to exhibit an appropriate reference for comprehensive research trends in HC estimation and optimization based on ADNs. Additionally, it involves and covers most current research HC topics in detail compared to other published review articles. Moreover, the authors deliberate the recent approaches for evaluating and improving the HC, especially concerning data-driven methods, with the aid of various software for simulating real systems. Moreover, modern research trends and main factors of MPS operations are deliberated with current energy market developments. Also, prominent challenges, current status, and future aspects are discussed.

Due to improved efficiency of solar photovoltaic (PV) systems, this article proposes a modified perturb and observe (MPO) maximum power point tracking (MPPT) algorithm. The MPO algorithm in question adopts a tracking approach that divides the power-voltage curve into four operational regions based on the estimated open-circuit voltage. Additionally, this algorithm enhances the maximum power point (MPP) tracking method by reducing unnecessary step-size calculations, focusing only on a 10% section of the power-voltage curve that contains the MPP. Consequently, the two regions located far from the MPP, below 90% of the power-voltage range, utilize a large fixed step-size to ensure swift tracking speed. Furthermore, in the regions close to the MPP, the remaining areas employ a similar tracking strategy as the adaptive P&O algorithm, aiming to achieve minimal steady-state oscillations around the optimal MPP. The performance of the proposed MPO algorithm is demonstrated by validating it against sinusoidal, ramp irradiance, and one-day (10 hr.) irradiance profiles using MATLAB/SIMULINK. The simulation results confirm that the proposed algorithm outperforms recently published techniques in terms of convergence speed, achieving the shortest time of 15 ms, and slightly higher tracking efficiency of the PV system under uniform irradiation, reaching 99.8%.

Recently, various distributed energy resources are significantly integrated into the modern power systems. This introduction of distributed energy resource‐rich systems can cause various power quality issues, due to their uncertainties and capacity variations. Therefore, it is crucial to establish energy balance between generation and demand to improve power system's reliability and stability and to minimize energy costs without sacrificing customers’ comfort or utility. In this regard, power system flexibility concept is highlighted as a robust and cost‐effective energy management system, especially on the demand side, to provide consumers’ demands with an acceptable level of power quality. Accordingly, here, a comprehensive review of recent developments in the power system flexibility and demand‐side management strategies and demand response programs are provided to include mainly classifications, estimation methods, distributed energy resource modelling approaches, infrastructure requirements, and applications. In addition, current research topics for applying power system flexibility solutions and demand‐side management strategies based on modern power system operation are deliberated. Also, prominent challenges, research trends, and future perspectives are discussed. Finally, this review article aims to be an appropriate reference for comprehensive research trends in the power system flexibility concept in general and in demand‐side management strategies and demand response programs, specifically.