The increasing integration of renewable energy sources has accelerated the adoption of microgrids, necessitating efficient power-sharing and control techniques for reliable operation. This study proposes an optimized droop control technique for parallel inverters in islanded AC microgrids, focusing on improving system efficiency. Conventional droop methods often encounter challenges in power-sharing accuracy under varying load conditions due to mismatched feeder impedances and differing power loss characteristics of distributed generators (DGs). To address these issues, the proposed method dynamically adjusts droop coefficients using Particle Swarm Optimization (PSO) to optimize power distribution, reduce circulating currents, and improve energy conversion efficiency while maintaining system modularity. A system-level microgrid efficiency model is designed to identify optimal operating points under diverse load profiles. Comparative analysis demonstrates that the proposed PSO-based controller consistently outperforms conventional droop methods, achieving system efficiency improvements ranging from 0.11% to 0.52% across various load conditions and power factors. Simulation results from PSIM and MATLAB/Simulink further highlight reduced circulating currents, enhanced energy conversion efficiency, and improved system stability. These findings underscore the potential of PSO-driven control as a scalable and communication-free solution for efficiency optimization in decentralized microgrids. (c) 2025 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Microgrids, small-scale autonomous power systems, are becoming essential for incorporating renewable energy sources while improving the reliability and efficiency of electrical networks. These systems consist of multiple distributed generation units connected in parallel, which are controlled through coordinated strategies and can function in both grid-connected and islanded modes. Ensuring stability and effective load sharing in islanded microgrids, where the system operates independently, is critical to maintaining performance. Although numerous surveys have examined microgrid control techniques, few have systematically addressed hierarchical control methods from an efficiency standpoint. This paper presents a comprehensive review of droop control strategies in AC microgrids with distributed energy resources, focusing on hierarchical control approaches, power-sharing mechanisms, optimization challenges, and technical issues. Additionally, multiple control strategies are evaluated based on their benefits and drawbacks. A detailed analysis of several optimization techniques is also provided, highlighting their merits and demerits. Finally, the paper addresses emerging trends and potential future research directions for islanded microgrids.

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation A. M. Roslan, M. D. M. Shafiq, M. H. M. Hazwan, M. Syafiq A. K., Suhaimi Shahrin, M. N. Misbah, M. Ahmad; Flow rate and pH analysis in the design and development of 3D printed bio-media filtration for aquatic environment. AIP Conf. Proc. 7 March 2024; 2934 (1): 060012. https://doi.org/10.1063/5.0189727 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

The limited capacity of a single inverter has led to the implementation of parallel inverters for interconnecting renewable energy generation systems. Droop control is commonly used for operating parallel inverters; however, conventional droop control has a low conversion efficiency under heavy loads. Therefore, this paper designed an efficient control strategy to enhance the conversion efficiency of parallel inverters. The employed method incorporates an internal current and voltage control loop based on a synchronous reference frame, along with conventional PI controllers. Additionally, Particle Swarm Optimization (PSO) is utilized to determine the optimal conversion efficiency of the parallel inverters. In this approach, the distributed generation (DG) unit adjusts its control mode to modify system voltage and frequency in response to dynamic load conditions. Efficiency improvements were observed in the range of 0.19% to 0.41% across various initial power distribution ratios, highlighting the efficacy of optimized droop parameters in maintaining robust and efficient power systems. Simulation results using MATLAB/SIMULINK demonstrate that the proposed control system improves system efficiency

In this paper, a photovoltaic (PV) system based on modified duty cycle sweeping (MDCS) has been proposed to achieve the maximum power point tracking (MPPT). The disadvantages of perturb and observe (P&O), such as diverging tracking directions and the inability to detect the global peak during partial shading (PS), are intended to be overcome by this method (PS). An intelligent double identification and tracking method consistently tracks the global peak under partial shading and the MPP under rapid irradiance fluctuations. Strict dynamic irradiance and partial shading tests are imposed in MATLAB/Simulink @ and simulated to validate the suggested concept. Additionally, a laboratory prototype MPPT standalone PV system supported by Texas Instruments’ Code Composer Studio is operated by a SEPIC converter in conjunction with the C2000 real-time microcontroller in order to conduct an experimental validation study. The effectiveness of the method is compared with the other well-known MPPT techniques, conventional P&O. The suggested method successfully follows the global peak under various patterns of partial shading as compared to the conventional algorithms. The algorithm’s efficiency has been preserved at around 95-100%.

In a microgrid system, proper current distribution and load sharing strategies are essential to achieve reliable parallel operation. Line impedance is an important factor when implementing a control technique for an inverter for microgrid operation, whether it is operating in grid connected or island mode. It is sometime difficult to visualize the impact of different line impedance to the power flow in AC microgrid. In this paper, AC power flow of an inverter-based system connected to a common ac bus through purely resistive, inductive or complex line impedances is investigated. For each line impedance case, the effect of an inverter’s output voltage power angle and amplitude on the active and reactive power flow are studied. Several active and reactive powers plots are generated in 3D surf plots to visualize the impact of line impedance on the power flow in an AC system.

This paper presents a new control scheme that permits flexible power sharing between parallel inverters connected to microgrid operating in an island mode. The presented scheme processes the information of active and reactive output powers from all inverters in a central controller that calculates the set points for each inverter, based on the desired ratios of their output powers. These necessitate adjustment of the inverters’ terminal voltages (phase and magnitude) relative to the voltage at the common AC bus. The proposed power-sharing scheme uses a robust low bandwidth-based sharing communication to achieve precision and fast dynamic response, minimum circulating current between parallel inverters, and adapting to changes in line impedance, even under information transfer delays. The presented power-sharing scheme has been validated using MATLAB/Simulink simulation and experimental results obtained from a prototype of three three-phase parallel inverters connected to a number of loads. The results emphasize the superiority of the proposed topology performance under different loads (25% to 100%), line impedances, grid conditions, and communication delay.

A thin-walled tube is an energy absorber device that functions to dissipate kinetic energy into another form of energy during impact. The design of thin-walled tubes is a significant factor which affects to the energy absorption characteristics. This paper provides a comparative study between the original thin-walled tube designs and several modified tube designs that have been proposed. The main objective is to improve the energy absorption characteristics, such as energy absorption capacity, initial peak load, specific energy absorption (SEA) and crush force efficiency (CFE). Throughout this research, aluminium alloy AA6061-T6 has been used as the material for all tubes. For comparison, all of the tubes are developed with a circular shape with the same diameter, thickness and length. In addition, they are also impacted at the same kinetic energy under dynamic axial loading. Validated LS-DYNA finite element (FE) models have been used to simulate the impact of the thin-walled tubes. Compared to the original tube design, the modified tubes have improved energy absorption characteristics. A conical tube with a flat end cap was identified as the best performing tube among the modified tubes because it had the lowest initial peak load, a moderate energy absorption capacity and an excellent CFE and SEA. The findings from this study can be used as a guidance in designing thin-walled structure.

Concrete technology is life-long research, that strives to discover the best additives or admixtures that are able to produce good concrete in terms of physical, chemical and mechanical properties in a more economical, sustainable, environmental friendly and obtainable. This study focuses the effect of different percentages of EM toward strength of concrete. The compressive strength test was carried out to analyse these properties by using the concrete cubes with size 100 mm x 100 mm x 100 mm. These concrete mixes were tested at different ages which are 7, 14 and 28 days. Effective microorganism (EM) replacement percentages are 5%, 10% and 15% and the strength of concrete with EM replacement will be compared with the control sample. All the cubes were cured by immersed in the water for curing process before the compressive strength tests were conducted. The finding shows that the workability degree of EM mixture is similar with the conventional mixture. The compressive strength increase with the increment of EM content. The results shows that 10% of EM could be the optimum value of water replacement in concrete production to improve strength and durability.

A high penetration of renewable energy in power systems gives rise to the inverter based distributed generators (DG) in the current microgrid system. With the ability of microgrid to operate in both islanded and grid connected mode, a robust and reliable coordination and synchronization between the DGs and the utility grid is crucial to provide a seamless transition between operation modes. Droop based technique is the most popular method in microgrid system, however, voltage or current transient are present during mode transition. A power offset synchronization technique is proposed to provide a seamless transition between modes of operation. The results show that the mode transition is smooth and seamless without any voltage or current transients.

AbstractThe nationwide usage of cross-linked polyethylene (XLPE) for medium to high voltage distribution networks are practically common due to its excellent electrical, thermal and mechanical properties and widely installed through existing network of cable line in Malaysia. However, cable exposures to harsh climates coupled with inadvertent damage throughout installation or transportation are influencing the presence of voids inside the insulation leading to the initiation of partial discharges (PD) in the cable line. Therefore, this study is important to investigate the activities of PD due to the manifestation of voids in XLPE cable and how it affects the physical, electrical and mechanical characteristics of the cable. Analysis has been performed using Finite Element Analysis (FEA) tool to simulate the PD activities in a 2D model of a three (3) core-XLPE insulated armoured sheathed cable (500 mm2, 11 kV) with several placements of voids. The varied placement and radius of voids is very crucial in order to achieve comprehensive analysis. From the obtained result, it has been established that closest the void to the core yielded higher electric field potential. Additionally, it is verified from the simulation that the larger the size of void, the higher the electric field potential consequently increasing the current density inside the void. This simulation and analysis is quite important to provide better insight pertaining to the behaviour of PD in correspond to the presence of voids which will accelerate ageing failure in insulation framework of the XLPE cable.

This paper presents a droop control technique for equal power sharing in islanded microgrid. In this study, the proposed controller is based on the frequency droop method, is applied to a robust droop controller in parallel connected inverters. The previous robust droop controller deals with voltage droop method. A modification has been formed against this controller by adding a fuzzy logic controller with the frequency droop method. The only sharing error which is concentrated in this paper is the error in sharing the rated frequency among the inverters. By adapting fuzzy in the robust droop, it tries to eliminate the frequency error, hence that the frequency reference of the inverters keeps maintain at 50Hz. A derivation of generalized models of a single-phase parallel-connected inverter system is shown. The simulation results show that the proposed controller with FLC is able to improve the stability of frequency reference and the performance of power sharing between the inverters under the inductive line impedance.

Injection moulding process is a quite popular process in current industries to produce and replicate a various shape of plastic parts. However, the process involved a lot of processing parameters which is importance to control in order to minimise defect such as warpage. Nowadays, there are a lot of optimisation approaches that can be employed to obtain the suitable processing parameters setting to overcome this kind of defects. In this study, an artificial intelligent optimisation method which is Genetic Algorithm (GA) approach has been carried out to minimise warpage condition. The battery cover was tested with the selected processing parameters of packing time, cooling time, melting temperature, and mould temperature. Based on the Autodesk Mouldflow Insight (AMI) simulation results warpage value is 1.038 mm and GA approach demonstrated a warpage reduction and the results were 0.7005 mm. Thus, by utilising GA in minimising warpage on the moulded part can be applied in injection moulding sector.

Injection moulding process is a quite popular process in current industries to produce and replicate a various shape of plastic parts. However, the process involved a lot of processing parameters which is importance to control in order to minimise defect such as warpage. Nowadays, there are a lot of optimisation approaches that can be employed to obtain the suitable processing parameters setting to overcome this kind of defects. In this study, an artificial intelligent optimisation method which is Glowworm Swarm Optimisation (GSO) approach has been carried out to minimise warpage condition. The front panel housing was tested with the selected processing parameters of melting temperature, cooling time, packing pressure and packing time. Based on the Autodesk Mouldflow Insight (AMI) simulation results warpage value is 0.26 mm and GSO approach demonstrated a warpage reduction and the results were 0.2015 mm. Thus, by utilising GSO in minimising warpage on the moulded part can be applied in injection moulding sector.

Injection moulding process is a quite popular process in current industries to produce and replicate a various shape of plastic parts. However, the process involved a lot of processing parameters which is importance to control in order to minimise defect such as warpage. Nowadays, there are a lot of optimisation approaches that can be employed to obtain the suitable processing parameters setting to overcome this kind of defects. In this study, an artificial intelligent optimisation method which is Glowworm Swarm Optimisation (GSO) approach has been carried out to minimise warpage condition. The battery cover was tested with the selected processing parameters of packing time, cooling time, melting temperature, and mould temperature. Based on the Autodesk Mouldflow Insight (AMI) simulation results warpage value is 1.038 mm and GSO approach demonstrated a warpage reduction and the results were 0.931 mm. Thus, by utilising GSO in minimising warpage on the moulded part can be applied in injection moulding sector.

In designing a good furniture, there are three major aspects that should be considered; design, material selection, and strength. For strength aspects, the design of joint play a vital role as it needs to sustain the loads that applied on the furniture. The joint must capable to sustain the sufficient load and stay firm. In this study, three different designs of joint were proposed in order to determine the best joint design to be applied to the furniture. The Abaqus software was used to examine the strength of all three different designs. All three designs were constructed in T-shape with constant tenon (male) length and mortise (female). Among all three-proposed design, Design A provided the best result in terms of stress distribution and maximum displacement.

Generation of biofuels from renewable resources such as lignocellulosic biomass is a promising approach to reduce the sole reliability on the depleting fossil fuel. The aim of this work is to assess the potential environmental impact of bioethanol production from oil palm frond in a conceptual oil palm based biorefinery model, utilizing wet disc milling as a pretreatment method. A cradle-to-gate approach was selected, beginning with the harvesting and transportation of the frond petiole from the plantation, followed by production of oil palm frond petiole sugars via pretreatment and saccharification prior to bioethanol fermentation, and finally purification of the fermentation products to obtain anhydrous bioethanol. A life cycle assessment was performed using CML 2 baseline 2000 method (SimaPro v8.0), where ten impact categories were evaluated. It was found that the most significant environmental impact was from sugar recovery process with contribution of more than 90 %. This is mainly due to high power consumption by wet disc milling during pretreatment. Apart from that, production of enzyme and chemicals which were used during saccharification consumes high energy thus contributing major problems to the surrounding. Finding of this study helps to identify the hotspot which can be improved to establish a more energy efficient and greener system for bioethanol production from oil palm frond petiole sugars.

Average of about 53 million m(3) POME is being produced yearly in Malaysia. The treated palm oil mill effluent (POME) will be discharged to the river. However, the POME final discharge still contains high oxygen demand (COD) and suspended solids (SS) that potentially to cause environmental issues. Therefore, the aim of this study is to treat the POME final discharge with Napier grass (Pennisetum purpureum) in the constructed wetland system. This study has been carried out to investigate the feasibility of the Constructed Wetland in polishing the final discharge according to river quality index. Besides, the propagation of Napier grass in the POME final discharge was evaluated. Four different physicochemical parameters such as chemical oxygen demand (COD), total suspended solid (TSS), ammonia and colour were analysed based on standard laboratory methods and procedures. Results revealed that the reduction of COD level by 71.57 %, TSS by 83.59 %, ammonia by 85.97 % and colour reduced by 87.62 % after 15 days treatment time. In term of propagation of plant, Napier grass showed an excellent propagation in POME final discharge by 13.94% increment. The overall results indicated that treatment of POME final discharge by using Napier grass constructed wetland was successful to reduce the concentration of the contaminants.

Optimization in control method of microgrids attracted a great deal of attention of many researchers nowadays. In obtaining a robust controller that is capable in improving the quality of load power sharing and reducing losses thus increasing the performance and reliability of microgrids especially in islanded mode, droop based method is seem to be a popular option in many ways. The optimization methods justify the level of performance of a microgrid by enabling a robust control in controlling active and reactive power in ensuring stability, voltage regulation, as well as prevent the occurrence of circulating current. This paper strives to bring to light the review of control strategies involved in parallel connected inverters, obstruction in implementing droop method, and which optimization approaches were applied to empower the microgrid. An overview control strategy in islanded microgrid is also presented.

Coordination of different distributed generation (DG) units is essential to meet the increasing demand for electricity. Many control strategies, such as droop control, master-slave control, and average current-sharing control, have been extensively implemented worldwide to operate parallel-connected inverters for load sharing in DG network. Among these methods, the droop control technique has been widely accepted in the scientific community because of the absence of critical communication links among parallel-connected inverters to coordinate the DG units within a microgrid. Thus, this study highlights the state-of-the-art review of droop control techniques applied currently to coordinate the DG units within a microgrid.