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Compressed-air energy storage (CAES) is considered a promising energy storage system for many grid applications, including managing renewable variability and grid capacity concerns. However, compared with conventional generation such as coal or hydro, the cost of storage power of CAES is still high, which impedes its deployment. Therefore a standing question is how to operate CAES in the most efficient and economical fashion, that is, to exploit the system functions for maximum-possible benefit. This study investigates the CAES dynamic reactive capability used to stabilise wind farms under grid fault conditions. Two considered operation modes are motor mode with leading power factor and synchronous condenser mode. Analysis with a 60-MW wind farm and two types of popular wind turbines, namely stall-regulated and doubly fed induction-generator-based WTs, shows that the CAES performance is comparable or better than that of an static var compensator in most situations investigated. Therefore the reactive-power-supply function should be considered in CAES design and operation to increase the system efficiency and value.

The rapid increase in electric vehicle adoption, driven by their low maintenance, superior performance, and environmental benefits, has significantly elevated the demand on power distribution networks (PDNs). The integration of electric vehicle charging stations (EVCSs) into existing PDNs introduces critical operational challenges such as increased real power losses, reactive power losses, voltage deviations, and line congestion, which compromise system reliability and stability. To address these issues, this study proposes an enhanced optimization framework based on the Black Widow Optimization Algorithm (BWOA) and compares its performance against the conventional slime mould algorithm (SMA). The proposed model simultaneously determines the optimal placement and sizing of photovoltaic-based distributed generators (PV-DGs), distribution static compensators, and EVCSs, minimizing a normalized multiobjective function (MOF) that jointly considers real and reactive power losses, voltage deviation index, voltage stability index, and the total installation and operational cost. The framework is tested on the Institute of Electrical and Electronics Engineers 34-bus PDN under 24-h dynamic load variations and stochastic Photovoltaic system generation profiles. Simulation results demonstrate that BWOA significantly outperforms SMA in technical and economic performance. For instance, at hour 13, BWOA reduces real power losses to 48.48 kW, compared to 102.82 kW with SMA (a 52.8% improvement), while reactive power losses decrease from 30.4 kVAr to 14.41 kVAr (a 52.6% reduction). Voltage performance also improves, with the voltage deviation index reduced from 0.0574 to 0.0253 and the voltage stability index increased from 0.7896 to 0.9026 under BWOA, compared to 0.0314 and 0.8802 with SMA, respectively. Moreover, BWOA achieves significant economic benefits, reducing the total system cost from $16,745 to $15,892 at peak hours (5.1% savings). Over the 24-h horizon, the proposed BWOA-based strategy achieves an average MOF reduction of 35.7% compared to SMA, highlighting its superior capability to balance technical performance and economic feasibility. Overall, the findings underscore the effectiveness of coordinated PV-DG, distribution static compensators, and EVCS allocation in enhancing operational efficiency, voltage quality, and economic sustainability of modern distribution systems. The integration of cost components into the MOF formulation ensures a holistic optimization approach, making BWOA a promising solution for next-generation smart grid planning and real-time operational control.

In this paper, wind diesel-based hybrid electrical system is proposed as distributed generator (DG) for radial distribution system (RDS). Since renewable-based DGs and especially wind operated electric generating system requires reactive power for its excitation along with the reactive power demand for maintaining the voltage profile at all buses in RDS, a fast and adequate dynamic compensation is required along with DG. The main contribution of this paper is to optimize the amount of reactive power supplied by dynamic compensator using new proposed approach of least error voltage constraint iterative approach. The paper is starting with the selection procedure of most sensitive bus satisfying three voltage stability indices fast voltage security index, line quality factor and voltage stability index followed by the selection of DG optimal size using optimization approach with multiconstraints all together, namely total real and reactive power loss, voltage limits voltage stability indices and voltage stability indices. The result shows how the dynamic compensator can maintain voltage level by releasing additional reactive power with the adjustment of firing angle for different levels for multidynamic load changes.

Recently, voltage instability is considered as a key issue in the transmission line system due to its dynamic load pattern and increasing load demand. Flexible AC transmission systems (FACTS) devices are exploited to conserve the instability of voltage by controlling real and reactive power over the transmission system. In the transmission network, the size and position of FACTS are important considerations to provide a proper power flow in the system. In this paper, optimal sizing and assignment of FACTS are carried out by combining the kinetic gas molecular optimization (KGMO) and cuckoo search algorithm (CSA). There are three different FACTS devices used, namely Static VAR compensator, Thyristor Controlled Series Compensator and Unified Power Flow Controllers. The major objective functions of the proposed hybrid KGMO-CSA method are minimizing the installation cost, total voltage deviation (TVD), Line Loading and real power loss. Moreover, the optimal placement using the hybrid KGMO-CSA method is validated in MATLAB software by analyzing IEEE 14-, 30- and 57-bus system. Finally, the hybrid KGMO-CSA achieved 3.6442 MW power loss and 0.1007 p.u. TVD which is less when compared to existing quasi-oppositional chemical reaction optimization (QOCRO).

Reactive power compensation is a main problem in the control of electric power system. Reactive power from the source increases the transmission losses and reduces the power transmission ability of the transmission lines. In addition, reactive power must not be transmitted throughout the transmission line to a longer distance. Consequently, flexible ac transmission systems devices such as static compensator unified power-flow controller (UPFC) and static volt-ampere compensator are used to ease these harms. UPFC is the mainly adaptable and composite power electronic equipment that has emerged as the vital equipment for the control and optimisation of power flow in electrical power transmission system. In this study, a d–q model-based UPFC is developed with proportional-integral (PI) and PID controller. The above controllers are simulated using MATLAB and their performance is analysed. Outcome of the analysis shows the superiority of PID control over the PI control method. Also this study presents comparative evaluation (both controllers) of dynamic response when initial and final load disturbances.

The present paper focuses on embedded electrical networks (EEN) under electrical fault conditions. Indeed, the EEN can be affected by small or large disturbances, such as a low voltage ride through or a short-circuit in distribution or consumption parts of the embedded network. In fact, these problems can lead to the network instability and also affect the efficiency of marine vessels. In this work, the EEN can be converted into a flexible network by implementing the dynamic compensation devices. These devices can be considered as a synchronous machine that exchanges only the reactive power with EEN. Indeed, this compensation equipment entitled “Flexible AC Transmission System (FACTS)”, and it is used to improve the dynamic voltage stability of EEN. In this paper, the electrical network performances on the marine vessels are improved when the EEN is affected by small or large disturbances. Moreover, these improvements are achieved by integrating the automatic voltage regulator for ensuring the transient voltage stability, while the static VAr compensator (SVC) and static synchronous compensator (STATCOM) are implemented on the bus-bar of EEN to improve the dynamic voltage stability of the electrical network. The results of this study are obtained by using “Simulink/Matlab” software and a comparative analysis between the efficiency of SVC and STATCOM devices on the EEN stability is also presented.

A wind-diesel hybrid system integrates wind turbines and diesel generators for providing power that is reliable and efficient, specifically for remote or off-grid locations. The random nature of wind energy may lead to voltage swings and reactive power imbalances, which jeopardise system stability and power quality. Proper reactive power compensation is essential to ensure voltage stability along with power factor improvement and transmission line loss reduction. Here the static synchronous compensator is employed in a model for a wind-diesel hybrid system for compensation of reactive power to enable smooth operation of power. Transients have the most crucial role in monitoring the stability problems. A static synchronous compensator (STATCOM)-aided controller is also considered for the analysis of the behaviour of the proposed system. A Posicast Controller is a type of feed-forward controller utilised to reduce or suppress oscillations in system response. It does so by providing a control signal that zeroes out the oscillatory parts of system dynamics. With a STATCOM, the Posicast controller tries to enhance reactive power compensation transient response, leading to quicker voltage regulation, reduced overshoot and smaller settling time during disturbances. The Symbiotic Organism Search is one of the bio-inspired metaheuristic algorithms employed in the optimisation study of the hybrid system for transient analysis and others. The effectiveness of the Posicast controller in transient analysis to minimise settling time and reduce damping in oscillations is emphasised in the current study. The suggested algorithm is studied with established optimisation methods such as Ant Lion Optimisation (ALO), Gravitational Search Algorithm (GSA), Seeker Optimisation Algorithm (SOA) and Symbiotic Organism Search Optimisation (SOS) on the MATLAB platform. The suggested system attains a low steady-state error (Ess) of 0.0129, a rapid rise time (tr) of 7.8240, a rapid settling time (ts) of 8.0685 s and a very low peak overshoot (Mp) of 0.0321%, which guarantees better stability and optimal performance under dynamic operating conditions. The above results show that the suggested system achieves better accuracy than other methods under different operating conditions.

The Wind Energy Conversion system (WECS) integrated into modern power grids introduces significant challenges related to power quality, voltage stability, and harmonic distortion. To address these issues, this study proposes an advanced control strategy for a grid-connected Wind Energy Conversion System (WECS) based on a Permanent Magnet Synchronous Generator (PMSG), supported by a three-phase Distribution Static Compensator (DSTATCOM). The DSTATCOM is controlled using a novel hybrid intelligent algorithm Butterfly Generated Particle Swarm Optimization with PI control (BG-PSO-PI). This controller combines the global and local search capabilities of the Butterfly Optimization Algorithm with the fast convergence properties of Particle Swarm Optimization, ensuring robust performance under varying wind and load conditions. The proposed method effectively regulates DC-link voltage, enhances dynamic response, and provides accurate reactive power compensation. Additionally, it minimizes Total Harmonic Distortion (THD), achieving better power quality than conventional PI controller. The control algorithm dynamically adjusts the reference current by optimizing the fundamental weight values of load current, and generates precise gating signals through a Hysteresis controller. Simulation results demonstrate that the BG-PSO-PI-based DSTATCOM significantly improves voltage stability, reduces THD, and enhances overall power quality in smart grid environments, making it highly suitable for reliable and efficient renewable energy integration.

This paper introduces fractional-order capacitors and fractional-order inductors into the conventional integer-order cascaded H-bridge multilevel static compensator (ICHM-STATCOM), thereby constructing the main circuit of the fractional-order cascaded H-bridge multilevel static compensator (FCHM-STATCOM). Mechanism-based modeling is employed to establish switching function models and low-frequency dynamic models for the FCHM-STATCOM in the three-phase stationary coordinate system (a-b-c). Subsequently, fractional-order rotating coordinate transformation is introduced to establish the mathematical model of the FCHM-STATCOM in the synchronous rotating coordinate system (d-q). Additionally, a fractional-order proportional-integral (FOPI)-based fractional-order dual closed-loop current decoupling control strategy is proposed. Finally, this paper validates the correctness of the established mathematical models through digital simulation. Moreover, the simulation results demonstrate that by appropriately selecting the order of fractional-order capacitors and fractional-order inductors, the FCHM-STATCOM exhibits superior dynamic and static characteristics compared to the conventional ICHM-STATCOM, and the FCHM-STATCOM provides a more flexible reactive power compensation solution for power systems.

The use of Active Power Filters (APFs) in future power grids with high penetration of nonlinear loads is unavoidable. Voltage Source Inverters (VSIs) interfacing Photovoltaic (PV) generator could play the APF role in addition to power supply. In this paper, the control of a PV-fed multifunctional grid-connected three-phase VSI is addressed with nonlinear and unbalanced load. The control objective is threefold. The first one is to deliver the maximum available power from the PV source to the grid satisfying power quality standards. The second one is the Voltage Balancing Control for DC-link capacitors to guarantee correct operation of the VSI. The last one is shunt APF control to compensate for nonlinear and unbalanced load harmonics, reactive power, and unbalanced sequences. A quasi-Proportional-Resonant (PR) controller with harmonic compensators is proposed for the current control loop. The quasi-PR controller parameters are determined through optimization algorithms such as Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and a combination of both PSO and GA. The aim of the objective function is to improve static and dynamic behavior. The different gains at the fundamental resonant frequency and the selected odd harmonics are obtained for the proposed quasi-PR controller. The dynamic characteristics of the optimized quasi-PR controllers show superiority against conventional ones in terms of gain margin, phase margin, overshoot, and robustness. With the proposed control scheme, the harmonics, reactive power, and unbalanced sequences are appropriately compensated. The performance of the PV-fed VSI shunt APF under irradiance change, load change, and distorted grid voltage conditions is validated through numerical simulations performed on PSIM © software. The results show that the grid currents Total Harmonic Distortion for irradiance change case study are 4.57 % , 4.57 % , and 3.22 % in phase a , b , and c with the proposed control method, while they are 9.25 % , 5.65 % , and 10.12 % with conventional instantaneous p - q theory.