The increasing integration of renewable energy sources necessitates sustainable and cost-effective Energy Storage Systems (ESS) to mitigate intermittency and ensure grid stability. While Battery Energy Storage Systems (BESS) are widely deployed in Malaysia for their high energy density and fast response, their performance degradation and lifecycle limitations pose challenges to large-scale, long-duration applications. This study evaluates Gravity Energy Storage Systems (GESS) as an alternative by conducting a unified techno-economic, environmental, and operational performance analysis under identical photovoltaic (PV) conditions. A MATLAB-based, capacity-matched dynamic simulation model incorporating a 135 kWp PV system and a real-time energy management strategy is developed to compare GESS and BESS in terms of net usable energy, grid reliance, PV curtailment, and state-of-charge (SOC)-dependent behavior. Results demonstrate that GESS delivers higher net usable energy, achieves near-zero PV curtailment (0.005 % vs. 8.23 % for BESS), and reduces grid dependence, particularly across mid-range initial SOC levels. These simulation results align with the varied levelized cost projections documented in the literature for GESS and BESS. Overall, the analysis highlights that BESS is well-suited for short-term, high-power applications requiring rapid response, whereas GESS offers a high-capacity, cost-effective, and scalable solution for long-term energy shifting in solar-centric grids, emphasizing the need for further research on its deployment feasibility and long-term performance.

This paper investigates the enhancement of frequency stability in a multi-machine power system (MMPS) integrated with an offshore wind farm (OWF) and an energy storage system (ESS) by replacing the conventional integral controller with a reinforcement learning (RL) controller for automatic generation control (AGC) of synchronous generators (SGs). The performance of the proposed RL controller under system disturbances is validated using dynamic time-domain simulations. The simulation results show that the stability of the studied system can be effectively improved by the designed RL controller located at the AGC of the SGs under disturbance conditions.

This paper proposes the integration of a hybrid renewable energy system (HRES) and an energy storage system (ESS) into a two-area multimachine power system (MMPS), with an analysis of stability enhancement. The HRES comprises a permanent magnet synchronous generator (PMSG)-based offshore wind farm (OWF), a doubly-fed induction generator (DFIG)-based OWF, and a photovoltaic (PV) farm. The ESS utilizes a vanadium redox flow battery (VRFB) and incorporates a genetic algorithm (GA)-based supplementary damping controller (SDC) within its bidirectional DC/DC converter to optimize the stability improvement of the MMPS. This study compares the studied system under three scenarios: without SDC, a conventional SDC, and the proposed GA-based SDC. Time-domain analysis of dynamic and transient simulations validates the effectiveness of the proposed GA-based SDC. Simulation results indicate that, compared to other scenarios, the proposed GA-based SDC significantly enhances the stability of the studied system.

Bifacial photovoltaic (PV) systems harvest solar energy from both front and rear surfaces, typically achieving 7–16% higher electricity yield than monofacial systems in non-tropical regions at a 2–5% higher module cost. However, their performance in tropical climates remains insufficiently studied, particularly under denser array layouts and the absence of snow-related effects. Limitations in existing studies, such as short-term observations, simplified assumptions, and non-representative system configurations, may lead to incomplete performance evaluation. This study addresses these gaps through a long-term field investigation combining a continuous 7-month dataset with additional measurements over 14 months under realistic system configurations in a tropical environment. The study focuses on n-type TOPCon PV modules and implements a comprehensive measurement framework, including direct in-plane rear-side irradiance (IPRI) measurement, normalization, and degradation assessment. Techno-economic and sensitivity analyses were also conducted based on experimentally derived performance data. The results show that module-level bifacial gain ranges from 7.6% to 17.1%, depending on ground material, diffuse irradiance fraction, and array configuration. System-level bifacial gains are 15.2% (white gravel), 10.1% (concrete), 9.3% (green grass) and 9.1% (soil), demonstrating performance comparable to non-tropical regions. The temperature-corrected average daily specific yield reaches 4.72 kWh/kW/day for white gravel, corresponding to a 17.1% improvement over monofacial systems. Degradation rates of 3.3%–3.8% for p-type modules and 1.8%–2.1% for n-type modules indicate accelerated performance loss under tropical conditions. IPRI exceeds 300 W/m², occurring concurrently with high front-side irradiance, highlighting the need to revise existing international design and safety considerations standards. A 25-year techno-economic analysis of a 10 MW system shows that bifacial PV with white gravel reduces the payback period from 7.17 to 6.13 years and lowers the levelized cost of electricity by 12% (from RM 0.134 to RM 0.118/kWh). These results demonstrate that bifacial PV systems are both technically and economically viable in tropical regions.

This paper presents the stability analysis results of integrating various renewable energy sources (RESs) into a multimachine power system (MMPS) via a multi-terminal high-voltage direct-current (MT-HVDC) link based on a modular multilevel converter (MMC). The RESs consist of a floating offshore wind farm (FOWF), a fixed-base offshore wind farm (FBOWF), and an ocean thermal energy conversion (OTEC) system, while the MMPS comprises four large synchronous generators (SGs). This study first performs small-signal stability analysis under various operating conditions. Based on the identified low-frequency oscillation (LFO) modes, a supplementary damping controller (SDC) for the MMC of the MT HVDC link is designed to improve the damping of the LFO modes. Finally, dynamic and transient time-domain simulations are conducted to evaluate the SDC’s performance under various disturbance scenarios.

This paper presents the stability analysis results of a hybrid renewable energy system (HRES) connected to a multi-machine power system (MMPS) via a three-terminal high-voltage direct current (3T-HVDC) link based on a modular multilevel converter (MMC). The HRES includes an offshore wind farm (OWF) based on a permanent magnet synchronous generator (PMSG) and a photovoltaic (PV) plant, each interfaced through the MMC-based 3T-HVDC link. Three control strategies— grid-following (GFL), grid-forming (GFM), and GFM with particle swarm optimization (PSO-GFL)—are proposed to address inertia and parameter sensitivity. Their performance is assessed via steady-state, small-signal, and dynamic simulations under various operating scenarios.

This paper investigates a hybrid energy storage system (HESS) consisting of a vanadium redox flow battery (VRFB) and a supercapacitor (SC), integrated into a large offshore wind farm (OWF) and a parallel offshore platform (OP). The power of the OP is efficiently and stably transmitted to a land-based multi-machine power system (MMPS) with two-area four synchronous generators (SGs) through a high-voltage direct current (HVDC) link based on a modular multi-level converter (MMC). To further enhance the system’s stability and response performance, this paper employs modal control theory to design a proportional-integral-derivative (PID) supplementary damping controller (SDC) for the MMC. The grey wolf optimization (GWO) algorithm is employed to update the three key parameters of the PID SDC by optimizing its performance. In the small-signal stability analysis and dynamic analysis, different cases are compared. For dynamic studies, simulations are conducted by incorporating actual offshore wind speed variations to compare the system’s stability under various scenarios.

Regenerative braking energy (RBE) recovery plays a vital role in improving the energy efficiency and sustainability of electric rail transit systems. In DC third rail systems, the effectiveness of RBE recovery is influenced by various operational and infrastructural factors, particularly track elevation and curvature. This study analyzes the impact of these two key parameters on RBE recovery within the context of a DC third rail system. A comprehensive simulation model was developed using ETAP software, reflecting the actual traction power network of Malaysia’s Mass Rapid Transit Line 2 (MRT Line 2). Multiple scenarios were assessed to evaluate how changes in track gradients and curvature radii affect the energy recovered during braking. The findings reveal that track elevation significantly influences total energy consumption and the amount of RBE that can be effectively harnessed. These insights are crucial for optimizing train operations and track design to maximize energy recovery and support the development of greener rail transport systems.

Due to the intermittent nature of renewable energy sources (RESs) such as wind farms or solar farms, integrating these RESs into power systems can result in instability, affecting the power system's quality and stability. To address this issue, various energy storage systems (ESSs) used to compensate for power fluctuations or different flexible AC transmission systems (FACTS) used to control voltage magnitude and active/reactive power injections were proposed to improve the stability of the connected power systems. Some effective supplementary damping controllers (SDCs) need to be designed by using suitable control theory for the ESSs or the FACTS devices to achieve the goal of stability improvement. A static synchronous compensator (STATCOM) joined with a vanadium redox flow battery (VRFB)-based ESS is proposed to suppress subsynchronous resonance (SSR) occurring in a hybrid steam-turbine generator (STG)/offshore wind farm (OWF) system fed to an infinite bus through a series-capacitor compensated line. The OWF is based on a doubly-fed induction generator, and the d-q axis equivalent-circuit model of the studied system under three-phase balanced loading conditions is derived to establish the complete system model. An SDC of the STATCOM is designed using modal control theory to improve the damping of the dominant modes of the studied system. Small-signal stability and dynamic simulation results of the studied system are systematically performed to demonstrate that the STATCOM joined with the proposed VRFB-ESS with the designed SDC effectively suppresses the studied system's SSR.

This paper investigates voltage-stability improvement of bus nodes within four microgrid clusters (MGCs) based on the IEEE 14-bus system. Wind and PV systems are added to the generator sides of the microgrids (MGs), and electric vehicle (EV) loads are added to the load sides to simulate practical power system situations. Unified power-flow controllers (UPFCs) are added to the transmission lines between neighboring MGs to improve their voltage stability. For static voltage stability, frequency-domain characteristics of the studied MGCs under different line-outage scenarios are first performed through Q-V sensitivity analysis, and the system load margin is evaluated using P-V curves. For the transmission-line stability of the studied MGCs, a critical X-R ratio index derived from an extension of the fast voltage stability index (FVSI) is proposed.

The design and implementation of electrical distribution networks significantly influences customers' capital expenditure (CAPEX) and operational expenditure (OPEX) when scaling infrastructure to meet increased power demand. For customers with a maximum demand for a single premise from 5 MVA up to 10 MVA, the power utility companies in the ASEAN region have several power supply voltage schemes. The merits of employing the 11 kV power supply voltage schemes as compared to the 33 kV power supply voltage schemes for customers requiring marginally above 5 MVA are presented in this paper. The CAPEX and OPEX associated with 33 kV power supply voltage schemes for a single premise are found to be substantially higher than those for independent 11 kV power supply voltage schemes. This creates a financial obstacle for customers intending for infrastructure expansion and requires marginal increases in power demand - such as those needing only 6 MVA. This study reviews these customers' current electrical distribution network practices and power supply voltage schemes. The paper evaluates the economic and operational implications of 33 kV and 11 kV power supply voltage schemes for a single premise. By analyzing these factors, areas for policy reform to reduce both initial capital expenditure and ongoing operational costs for customers are identified while supporting competitive infrastructure expansion. The paper concludes with strategic recommendations for policy adjustments to better meet the needs of businesses seeking competitive infrastructure investment.

This paper presents the stability-analysis results of a doubly-fed induction generator (DFIG)-based offshore wind farm (OWF) connected to the bus of the synchronous generator of the IEEE Second Benchmark Model (SBM), system-1. The interline power-flow controller (IPFC) is proposed to suppress the studied system’s subsynchronous resonance (SSR) and other unstable modes. The d-q axis equivalent-circuit model under three-phase balanced loading conditions establishes the studied complete system model. A damping controller of the proposed IPFC is designed using a pole-assignment approach based on modal control theory to suppress unstable SSR and other unstable modes of the studied system. To demonstrate the effectiveness of the proposed control scheme, a frequency-domain approach based on eigenvalue analysis and a time-domain scheme based on transient simulations are both performed. The simulation results show that the proposed IPFC, joined with the designed damping controller, can effectively suppress the studied system’s unstable SSR phenomena and other unstable modes.

This paper analyzes the stability of a multi-terminal high-voltage direct current (MTHVDC) link based on a modular multilevel converter (MMC) to integrate an offshore wind farm (OWF) and an ocean thermal energy conversion system (OTECS) into two power grids. The results of small-signal stability of the studied system under different operational conditions are first examined. The damping controllers for the MMC to damp low-frequency oscillations of the studied system are designed using modal control theory. Dynamic responses of a nonlinear system model subject to a disturbance finally evaluate the damping controllers’ performance. The simulation results show that the designed damping controller for the MMC of the MTHVDC can improve the stability of the studied system subject to different operating conditions and disturbances.

Objectives of current work focuses on the optimization of wireless charging system parameters, specifically tailored for electric vehicles (EVs). As the global demand for effectives charging solutions for EVs grows, optimizing the performance of wireless charging infrastructure becomes critical. This research investigates key parameters such as coil design and alignment accuracy to enhance the efficiency and effectiveness of wireless power transfer. The design incorporates bipolar coils, which have been proven to provide the highest coupling efficiency. Simulation results from Ansys Maxwell indicates that precise tuning of coil configurations can significantly improve performance.

Fuzzy clustering has emerged as a powerful technique for analyzing complex, uncertain, and high-dimensional data across diverse application domains, including pattern recognition, bioinformatics, image analysis, and decision support systems. Unlike classical clustering, which assigns each data instance to a single cluster, fuzzy clustering allows partial membership, thereby capturing inherent ambiguity in real-world datasets. This review provides a comprehensive examination of heuristic-based fuzzy clustering algorithms. We begin by outlining the fundamental concepts of clustering, fuzzy set theory, and the principles of fuzzy clustering. Subsequently, we discuss the evolution of core algorithms, including Fuzzy C-Means (FCM) and Possibilistic C-Means (PCM), and highlight significant modifications derived from altering distance metrics, objective functions, and optimization strategies. Particular emphasis is placed on heuristic and metaheuristic enhancements—such as genetic algorithms, particle swarm optimization, and artificial immune systems—that address the limitations of classical approaches, including sensitivity to initialization, susceptibility to noise and outliers, and premature convergence. Recent contributions in hybrid fuzzy clustering are also reviewed, with attention to their strengths, weaknesses, and potential applications. Finally, we synthesize insights from the literature to categorize the persistent disadvantages of existing methods and identify promising directions for future research, including adaptive fuzzifiers, noise-resilient models, and integration with evolutionary computation. This study not only consolidates advances in heuristic-based fuzzy clustering but also provides guidance for researchers aiming to design more robust, scalable, and application-driven clustering algorithms.

This paper presents the stability-analysis results of a hybrid renewable-energy farm (HREF) connected to the IEEE 14-bus multimachine power system (MMPS) through a high-voltage direct-current (HVDC) link based on a modular multilevel converter (MMC). The HRES consists of a wind farm based on a doubly-fed induction generator (DFIG) and a PV farm based on a PV array. A voltage-source inverter (VSI) using a grid-forming (GFM) control scheme in the PV farm is proposed to mitigate the impact of the lack of inertial support using a grid-following (GFL) control scheme. For small-signal stability analysis, the root-loci plots of the studied system using the GFL and the GFM control strategies are compared. The transient results of the studied system subject to an islanding condition using the GFM and the GFL control strategies are also compared. The simulation results indicate that the studied system using the GFM control scheme demonstrates better damping performance on the HREF than the GFL control scheme.

This paper presents the stability analysis results of a synchronous generator (SG) connected to an infinite bus through a high-voltage direct current (HVDC) link based on a modular multilevel converter (MMC). The MMC-HVDC consists of different control strategies for the MMC at the SG side (SS-MMC) and the MMC at the grid side (GS-MMC) to operate with different current directions and operating modes. The stability analysis of the studied system includes the small-signal stability analysis using both eigenvalues and root-loci plots as well as the accuracy validation of the derived mathematical model for using dynamic simulations.

This paper investigates the impact of ground materials and albedo on the performance of bifacial photovoltaic (PV) modules in tropical regions. This research holds significance as it fills a critical gap in the existing literature, providing a comprehensive exploration of bifacial gain and albedo in tropical regions using an experimental setup. The experimental setup involved the installation of monofacial and bifacial PV modules with standard installation practices commonly employed in Malaysia. Various ground materials-concrete, white gravel, soil, and grass-were placed beneath the panels to analyze their effects on module performance. At the end of the study, the results showed the potential of a bifacial PV system in the tropics. The calculated bifacial gain in this study ranges from 8.7 % to 16.5%, depending on the ground materials applied. Compared to other bifacial PV system design research using only simulations, this paper emphasizes the importance of considering albedo variability, which could significantly impact bifacial gain in tropical regions. The results demonstrate a linear relationship between albedo and bifacial gain values. This study provides valuable insights for the PV industry, offering guidance in module selection for cost-effective PV plant installations. The calculated albedo and bifacial gain will serve as the reference range for the PV industry.

This paper proposes a vanadium redox flow battery (VRFB)-based energy storage system (ESS) to achieve grid-resilience enhancement of a multimachine power system (MMPS) connected with a DC microgrid (MG). The proposed VRFB-ESS is connected to the common DC link of the DC MG through a bidirectional DC/DC converter to perform both energy balance and voltage control of the DC MG consisting of a high-capacity hybrid wind/PV farm. The complete system model with the hybrid wind/PV farm, the VRFB-ESS, and the MMPS is established and analyzed to demonstrate the grid-resilience enhancement of the employed VRFB-ESS. The simulation results show that the proposed VRFB-ESS can offer better grid resilience on energy dispatch of the studied system under severe weather conditions.

This paper investigates the voltage-stability improvement of bus nodes within four microgrids (MGs) clusters based on the IEEE 14-bus test system using unified power flow controllers (UPFCs). Wind and solar power generation systems are integrated into the studied four MGs as renewable energy sources (RESs) to simulate practical power-system conditions. At the same time, electric-vehicle (EV) loads are added to the load side of the studied four MGs. The UPFCs are introduced into the transmission lines between nearby MGs to enhance the voltage stability of the proposed architecture. An examination of the static voltage stability of the studied system is first performed. The characteristics of the studied system under various line-outage scenarios are observed through the system load margin and theP-Vcurves. For transmission line stability, a fast voltage stability index (FVSI) is proposed for assessment. Time-domain responses of the buses of the studied system under different line-outage scenarios are also achieved to explore the dynamic voltage stability.