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Radio Frequency Identification (RFID) and communication technologies for solid waste bin and truck monitoring system

Hannan MA, Arebey M, Begum RA, Basri H

Waste Manag, 2011 Dec;31(12):2406-13.
PMID: 21871788 DOI: 10.1016/j.wasman.2011.07.022

This paper deals with a system of integration of Radio Frequency Identification (RFID) and communication technologies for solid waste bin and truck monitoring system. RFID, GPS, GPRS and GIS along with camera technologies have been integrated and developed the bin and truck intelligent monitoring system. A new kind of integrated theoretical framework, hardware architecture and interface algorithm has been introduced between the technologies for the successful implementation of the proposed system. In this system, bin and truck database have been developed such a way that the information of bin and truck ID, date and time of waste collection, bin status, amount of waste and bin and truck GPS coordinates etc. are complied and stored for monitoring and management activities. The results showed that the real-time image processing, histogram analysis, waste estimation and other bin information have been displayed in the GUI of the monitoring system. The real-time test and experimental results showed that the performance of the developed system was stable and satisfied the monitoring system with high practicability and validity.

Matched MeSH terms: Computer Systems/economics*
Fulltext Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results

Humada AM, Hojabri M, Sulaiman MH, Hamada HM, Ahmed MN

PLoS One, 2016;11(4):e0152766.
PMID: 27035575 DOI: 10.1371/journal.pone.0152766

A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions.

Matched MeSH terms: Computer Systems
Fulltext Performance Evaluation of Localization Accuracy for a Log-Normal Shadow Fading Wireless Sensor Network under Physical Barrier Attacks

Hussein AA, Rahman TA, Leow CY

Sensors (Basel), 2015;15(12):30545-70.
PMID: 26690159 DOI: 10.3390/s151229817

Localization is an apparent aspect of a wireless sensor network, which is the focus of much interesting research. One of the severe conditions that needs to be taken into consideration is localizing a mobile target through a dispersed sensor network in the presence of physical barrier attacks. These attacks confuse the localization process and cause location estimation errors. Range-based methods, like the received signal strength indication (RSSI), face the major influence of this kind of attack. This paper proposes a solution based on a combination of multi-frequency multi-power localization (C-MFMPL) and step function multi-frequency multi-power localization (SF-MFMPL), including the fingerprint matching technique and lateration, to provide a robust and accurate localization technique. In addition, this paper proposes a grid coloring algorithm to detect the signal hole map in the network, which refers to the attack-prone regions, in order to carry out corrective actions. The simulation results show the enhancement and robustness of RSS localization performance in the face of log normal shadow fading effects, besides the presence of physical barrier attacks, through detecting, filtering and eliminating the effect of these attacks.

Matched MeSH terms: Computer Systems
Fulltext Passive damping techniques with LCL filter in inverter-grid connected

Erum Pathan, Shamsul Aizam Zulkifli

Pertanika Journal of Science & Technology, 2017;25(102):45-52.
MyJurnal

In this paper, the challenge of harmonic injection mitigation becomes critical with the massive use of inverters in electrical distribution systems that has been discussed and analyzed. Currently, between the inverter and the grid, L, LC or LCL filters is often used to mitigate the current harmonic. Further, filter connection in both delta-to-star or star-to-delta transformer for state space model of LC filter couplings with impedance is obtained in this paper and it also talked about the different passive damping techniques that been used to suppress the resonance effect on the filter. The effect of series and parallel damping resistor techniques that impact filtering and stability are also been analyzed and discussed. At the end, the simulation results show that LCL filter with parallel damping resistor achieves best performance compared on those for L, LC, or LCL with series damping resistor while at the same time enhancing the smoothness of the signal output while at the same time reducing the percentage of total harmonic distortion between inverter-grid connection.

Matched MeSH terms: Computer Systems
Fulltext PRESIMS: Requirements and design for Preschool Management System using usability theory

Nor Hasnul Azirah Abdul Hamid, Normalina Ibrahim@Mat, Nurul Najihah Mustopa

ESTEEM Academic Journal, 2020;16(2):51-64.
MyJurnal

Student Information Management System (SIMS) is a computerized system for education that can be used to manage student information and data. PASTI An-Nur is chosen as a case study in developing the system. Thus, several problems are identified that PASTI An-Nur faces due to the
implementation of a manual system in the admission process. The first problem is the paper-based registration form that is prone to lose, misplaced and less secure. As for the payment process, arise a problem in term of higher error rate when checking and calculating the payments. The biggest downfall for PASTI An-Nur is the amount of space used to store all the students' files.
These problems bring inefficiency since the world is changing to computerized, where data management become one of the most significant issues nowadays. So, the aim of developing the Preschool Management System (PRESIMS) is for helping the staffs and teachers in managing the
students' information. The Adapter Waterfall model was used in developing this system. Additionally, usability heuristics was used also as a theory to guide the development of this system. The system has been tested with the four (4) users and two (2) experts. The testing method is the ISO/IEC 9126- 4 approach to measure usability metrics, including efficiency, effectiveness, and satisfaction. Whereas, for the experts, heuristic evaluation is used to bring six (6) usability principles into implementation for testing. The result of the testing is very satisfying, which shows 75.5% of efficiency, 83.33% of effectiveness and three (3) out of four (4) users very satisfied with the system. The result of heuristic evaluation also shows a successful implementation of the system. The details of the result are discussed in this paper and expected to meet the users' specification and it is ready to go live.

Matched MeSH terms: Computer Systems
Objective assessment of vitiligo with a computerised digital imaging analysis system

Shamsudin N, Hussein SH, Nugroho H, Fadzil MH

Australas J Dermatol, 2015 Nov;56(4):285-9.
PMID: 25367709 DOI: 10.1111/ajd.12247

An objective tool to quantify treatment response in vitiligo is currently lacking. This study aimed to objectively evaluate the treatment response in vitiligo by using a computerised digital imaging analysis system (C-DIAS) and to compare it with the physician's global assessment (PGA). Tacrolimus ointment 0.1% (Protopic; Astellas Pharma Tech,Toyama, Japan) was applied twice daily on selected lesions which were photographed every 6 weeks for 24 weeks. The primary efficacy end-point was the mean percentage of repigmentation (MPR), as assessed by the digital method (MPR-C-DIAS) or by the PGA. The response was categorised into none (0%), mild (1-25%), moderate (26-50%), good (51-75%) and excellent (76-100%).

Matched MeSH terms: Computer Systems
Fulltext Neuropsychiatric manifestations of neurosyphilis: a case report

Abdul Taib, N.I., Seed, H.F., Yeoh, C.M., Thon,g K.S.

Malaysian Journal of Psychiatry, 2016;25(1):0-0.
MyJurnal

Neurosyphilis has been known to present with wide array of neuropsychiatric
signs and symptoms. However little is known of the severity of its
manifestations especially in our Malaysia setting. We are reporting a case of
a middle-aged ex-military Malay man who contracted neurosyphilis during
active service and since then had severe neuropsychiatric symptoms which
caused deterioration in his activities of daily living skills which warrants
constant supervision. We discuss the various presentations of neurosyphilis
and its sequelae despite completion of antibiotics treatment.

Matched MeSH terms: Computer Systems
Fulltext Multiple adaptive neuro-fuzzy inference system with automatic features extraction algorithm for cervical cancer recognition

Al-batah MS, Isa NA, Klaib MF, Al-Betar MA

Comput Math Methods Med, 2014;2014:181245.
PMID: 24707316 DOI: 10.1155/2014/181245

To date, cancer of uterine cervix is still a leading cause of cancer-related deaths in women worldwide. The current methods (i.e., Pap smear and liquid-based cytology (LBC)) to screen for cervical cancer are time-consuming and dependent on the skill of the cytopathologist and thus are rather subjective. Therefore, this paper presents an intelligent computer vision system to assist pathologists in overcoming these problems and, consequently, produce more accurate results. The developed system consists of two stages. In the first stage, the automatic features extraction (AFE) algorithm is performed. In the second stage, a neuro-fuzzy model called multiple adaptive neuro-fuzzy inference system (MANFIS) is proposed for recognition process. The MANFIS contains a set of ANFIS models which are arranged in parallel combination to produce a model with multi-input-multioutput structure. The system is capable of classifying cervical cell image into three groups, namely, normal, low-grade squamous intraepithelial lesion (LSIL) and high-grade squamous intraepithelial lesion (HSIL). The experimental results prove the capability of the AFE algorithm to be as effective as the manual extraction by human experts, while the proposed MANFIS produces a good classification performance with 94.2% accuracy.

Matched MeSH terms: Computer Systems
Multi-sources data fusion framework for remote triage prioritization in telehealth

Salman OH, Rasid MF, Saripan MI, Subramaniam SK

J Med Syst, 2014 Sep;38(9):103.
PMID: 25047520 DOI: 10.1007/s10916-014-0103-4

The healthcare industry is streamlining processes to offer more timely and effective services to all patients. Computerized software algorithm and smart devices can streamline the relation between users and doctors by providing more services inside the healthcare telemonitoring systems. This paper proposes a multi-sources framework to support advanced healthcare applications. The proposed framework named Multi Sources Healthcare Architecture (MSHA) considers multi-sources: sensors (ECG, SpO2 and Blood Pressure) and text-based inputs from wireless and pervasive devices of Wireless Body Area Network. The proposed framework is used to improve the healthcare scalability efficiency by enhancing the remote triaging and remote prioritization processes for the patients. The proposed framework is also used to provide intelligent services over telemonitoring healthcare services systems by using data fusion method and prioritization technique. As telemonitoring system consists of three tiers (Sensors/ sources, Base station and Server), the simulation of the MSHA algorithm in the base station is demonstrated in this paper. The achievement of a high level of accuracy in the prioritization and triaging patients remotely, is set to be our main goal. Meanwhile, the role of multi sources data fusion in the telemonitoring healthcare services systems has been demonstrated. In addition to that, we discuss how the proposed framework can be applied in a healthcare telemonitoring scenario. Simulation results, for different symptoms relate to different emergency levels of heart chronic diseases, demonstrate the superiority of our algorithm compared with conventional algorithms in terms of classify and prioritize the patients remotely.

Matched MeSH terms: Computer Systems
Fulltext Monte Carlo method with heuristic adjustment for irregularly shaped food product volume measurement

Siswantoro J, Prabuwono AS, Abdullah A, Idrus B

ScientificWorldJournal, 2014;2014:683048.
PMID: 24892069 DOI: 10.1155/2014/683048

Volume measurement plays an important role in the production and processing of food products. Various methods have been proposed to measure the volume of food products with irregular shapes based on 3D reconstruction. However, 3D reconstruction comes with a high-priced computational cost. Furthermore, some of the volume measurement methods based on 3D reconstruction have a low accuracy. Another method for measuring volume of objects uses Monte Carlo method. Monte Carlo method performs volume measurements using random points. Monte Carlo method only requires information regarding whether random points fall inside or outside an object and does not require a 3D reconstruction. This paper proposes volume measurement using a computer vision system for irregularly shaped food products without 3D reconstruction based on Monte Carlo method with heuristic adjustment. Five images of food product were captured using five cameras and processed to produce binary images. Monte Carlo integration with heuristic adjustment was performed to measure the volume based on the information extracted from binary images. The experimental results show that the proposed method provided high accuracy and precision compared to the water displacement method. In addition, the proposed method is more accurate and faster than the space carving method.

Matched MeSH terms: Computer Systems
Modified recurrent equation-based cubic spline interpolation for missing data recovery in phasor measurement unit (PMU)

Thangaraj S, Goh VT, Yap TTV

F1000Res, 2022;11:246.
PMID: 38152076 DOI: 10.12688/f1000research.73182.3

BACKGROUND: Smart grid systems require high-quality Phasor Measurement Unit (PMU) data for proper operation, control, and decision-making. Missing PMU data may lead to improper actions or even blackouts. While the conventional cubic interpolation methods based on the solution of a set of linear equations to solve for the cubic spline coefficients have been applied by many researchers for interpolation of missing data, the computational complexity increases non-linearly with increasing data size.
METHODS: In this work, a modified recurrent equation-based cubic spline interpolation procedure for recovering missing PMU data is proposed. The recurrent equation-based method makes the computations of spline constants simpler. Using PMU data from the State Load Despatch Center (SLDC) in Madhya Pradesh, India, a comparison of the root mean square error (RMSE) values and time of calculation (ToC) is calculated for both methods.
RESULTS: The modified recurrent relation method could retrieve missing values 10 times faster when compared to the conventional cubic interpolation method based on the solution of a set of linear equations. The RMSE values have shown the proposed method is effective even for special cases of missing values (edges, continuous missing values).
CONCLUSIONS: The proposed method can retrieve any number of missing values at any location using observed data with a minimal number of calculations.

Matched MeSH terms: Computer Systems*
Fulltext Minimizing thermal stress for data center servers through thermal-aware relocation

Chaudhry MT, Ling TC, Hussain SA, Manzoor A

ScientificWorldJournal, 2014;2014:684501.
PMID: 24987743 DOI: 10.1155/2014/684501

A rise in inlet air temperature may lower the rate of heat dissipation from air cooled computing servers. This introduces a thermal stress to these servers. As a result, the poorly cooled active servers will start conducting heat to the neighboring servers and giving rise to hotspot regions of thermal stress, inside the data center. As a result, the physical hardware of these servers may fail, thus causing performance loss, monetary loss, and higher energy consumption for cooling mechanism. In order to minimize these situations, this paper performs the profiling of inlet temperature sensitivity (ITS) and defines the optimum location for each server to minimize the chances of creating a thermal hotspot and thermal stress. Based upon novel ITS analysis, a thermal state monitoring and server relocation algorithm for data centers is being proposed. The contribution of this paper is bringing the peak outlet temperatures of the relocated servers closer to average outlet temperature by over 5 times, lowering the average peak outlet temperature by 3.5% and minimizing the thermal stress.

Matched MeSH terms: Computer Systems*
Fulltext Measurement of dosimetric parameters and dose verifi cation in stereotactic radiosurgery (srs)

Reduan Abdullah, Ahmad Zakaria, Nur Iziana Mohsin, Nik Ruzman Nik Idris, Ahmad Lutfi Yusof, Mazurawati Mohamed

Jurnal Sains Kesihatan Malaysia, 2015;13(1):39-49.
MyJurnal

The fi rst part of this study was about measurement of dosimetric parameters for small photon beams to be used as input
data for treatment planning computer system (TPS) and to verify the dose calculated by TPS in Stereotactic Radiosurgery
(SRS) procedure. The beam data required were percentage depth dose (PDD), off-axis ratio (OAR) and scattering factor.
Small beams of 5 mm to 45 mm diameter from a circular cone collimator in SRS were used for beam data measurements.
Measurements were made using pinpoint ionisation chamber (0.016cc). In the second part of this study, we reported
the important of carrying out quality assurance (QA) procedures before SRS treatment which were found to infl uence the
accuracy of dose delivery. These QA procedures consisted of measurements on the accuracy in target localization and
treatment room laser alignment. The calculated TPS dose for treatment was verifi ed using pinpoint ionisation chamber
and thermoluminescent detector (TLD) 100H. The deviation mean between measured and calculated dose was -3.28%.
The measured dose obtained from pinpoint ionisation chamber is in good agreement with the calculated dose from TPS
with deviation mean of 2.17%. In conclusion, pinpoint ionisation chamber gives a better accuracy in dose calculation
compared to TLD 100H. The results are acceptable as recommended by International Commission on Radiation Units
and Measurements (ICRU) Report No. 50 (1994) that dose delivered to the target volume must be within ± 5% error.

Matched MeSH terms: Computer Systems
MIMO model of an interacting series process for Robust MPC via System Identification

Wibowo TC, Saad N

ISA Trans, 2010 Jul;49(3):335-47.
PMID: 20304404 DOI: 10.1016/j.isatra.2010.02.005

This paper discusses the empirical modeling using system identification technique with a focus on an interacting series process. The study is carried out experimentally using a gaseous pilot plant as the process, in which the dynamic of such a plant exhibits the typical dynamic of an interacting series process. Three practical approaches are investigated and their performances are evaluated. The models developed are also examined in real-time implementation of a linear model predictive control. The selected model is able to reproduce the main dynamic characteristics of the plant in open-loop and produces zero steady-state errors in closed-loop control system. Several issues concerning the identification process and the construction of a MIMO state space model for a series interacting process are deliberated.

Matched MeSH terms: Computer Systems
Fulltext Low complexity smart grid security protocol based on elliptic curve cryptography, biometrics and hamming distance

Mutlaq KA, Nyangaresi VO, Omar MA, Abduljabbar ZA, Abduljaleel IQ, Ma J, et al.

PLoS One, 2024;19(1):e0296781.
PMID: 38261555 DOI: 10.1371/journal.pone.0296781

The incorporation of information and communication technologies in the power grids has greatly enhanced efficiency in the management of demand-responses. In addition, smart grids have seen considerable minimization in energy consumption and enhancement in power supply quality. However, the transmission of control and consumption information over open public communication channels renders the transmitted messages vulnerable to numerous security and privacy violations. Although many authentication and key agreement protocols have been developed to counter these issues, the achievement of ideal security and privacy levels at optimal performance still remains an uphill task. In this paper, we leverage on Hamming distance, elliptic curve cryptography, smart cards and biometrics to develop an authentication protocol. It is formally analyzed using the Burrows-Abadi-Needham (BAN) logic, which shows strong mutual authentication and session key negotiation. Its semantic security analysis demonstrates its robustness under all the assumptions of the Dolev-Yao (DY) and Canetti- Krawczyk (CK) threat models. From the performance perspective, it is shown to incur communication, storage and computation complexities compared with other related state of the art protocols.

Matched MeSH terms: Computer Systems
Fulltext Lightning performance analysis of a rooftop grid-connected solar photovoltaic without external lightning protection system

Nasir MSM, Ab-Kadir MZA, Radzi MAM, Izadi M, Ahmad NI, Zaini NH

PLoS One, 2019;14(7):e0219326.
PMID: 31295278 DOI: 10.1371/journal.pone.0219326

The Sustainable Energy Development Authority of Malaysia (SEDA) regularly receives complaints about damaged components and distribution boards of PV systems due to lightning strikes. Permanent and momentary interruptions of distribution circuits may also occur from the disturbance. In this paper, a solar PV Rooftop system (3.91 kWp) provided by SEDA was modelled in the PSCAD/EMTDC. The Heidler function was used as a lightning current waveform model to analyse the transient current and voltage at two different points susceptible to the influence of lightning events such as different lightning current wave shape, standard lightning current and non-standard lightning current. This study examines the effect on the system components when lightning directly strikes at two different points of the installation. The two points lie between the inverter and the solar PV array and between inverter and grid. Exceptionally high current and voltage due to the direct lightning strike on a certain point of a PV Rooftop system was also studied. The result of this case study is observed with and without the inclusion of surge protective devices (SPDs). The parameters used were 31 kA of peak current, 10 metres cable length and lightning impulse current wave shape of 8/20μs. The high current and voltage at P1 striking point were 31 kA and 2397 kV, respectively. As for the AC part, the current and voltage values were found to be 5.97 kA and 5392 kV, respectively.Therefore, SPDs with suitable rating provided by SEDA were deployed. Results showed that high transient current voltage is expected to clamp sharply at the values of 1.915 kV and 0 A at the P1 striking point. As for the AC part, the current and voltage values were found to be 0 kA and 0.751 V, respectively. Varying lightning impulse current wave shapes at striking point P2 showed that the highest voltage was obtained at waveshape 10/350 μs at 11277 kV followed by wave shapes of 2/70 μs, 8/20 μs and 0.7/6 μs. The high value of transient voltage was clamped at a lower level of 2.029 kV. Different lightning amplitudes were also applied, ranging from 2-200 kA selected based on the CIGRE distribution. It showed that the current and voltage at P1 and P2 were directly proportional. Therefore, the SPD will be designed at an acceptable rating and proper position of SPD installation at solar PV Rooftop will be proposed. The results obtained in this study can then be utilised to appropriately assign a SPD to protect the PV systems that are connected to the grid. Installing SPDs without considering the needs of lightning protection zones would expose the expensive equipment to potential damage even though the proper energy coordination of SPDs is in place. As such, the simulation results provide a basis for controlling the impacts of direct lightning strikes on electrical equipment and power grids and thus justify SPD coordination to ensure the reliability of the system.

Matched MeSH terms: Computer Systems
Fulltext Level of satisfaction in using the hospital information system among staff of a teaching hospital in Malaysia

Sangaran, G., Ahmad Taufik, J., Aniza, I.

Malaysian Journal of Public Health Medicine, 2014;14(1):29-38.
MyJurnal

Hospital information systems have evolved with the recent widespread, involving technology and target functions, and this involves the critical computer systems from multiple perspectives. Healthcare organizations increasingly use information technology as a basis for improving productivity and user satisfaction. A research had been done about the level of satisfaction in using the Hospital Information System. Data was obtained by using a set of questionnaires that have been tested for reliability and validity. The staff are comprised of two (2) categories: Nurses (community nurses / Head nurse / staff nurse, nurse managers and others) while the second category consists of administrative officers (administrative officers, administrative assistants and clerks) in selected departments. Variables consist of sociodemographic factors, occupational factors and perception factors. A total of 152 respondents identified using stratified sampling method. The factors studied were age, gender, marital status, level of qualifications, length of service, knowledge of the system, attitude towards the use of the system, behavioral intention to use the system and compatibility with work. Majority of respondents were females (88.2%). The level of satisfaction among the staff in using the hospital information system is high (88.8%) compared to the dissatisfied staff in UKMMC (11.2%). In overall, the staffs in UKMMC are satisfied using the hospital information system available now but there are always a room for improvement so that the system can be used more intensively.

Matched MeSH terms: Computer Systems
Fulltext Intelligent Malaysian Sign Language Translation System Using Convolutional-Based Attention Module with Residual Network

Khan RU, Khattak H, Wong WS, AlSalman H, Mosleh MAA, Mizanur Rahman SM

Comput Intell Neurosci, 2021;2021:9023010.
PMID: 34925497 DOI: 10.1155/2021/9023010

The deaf-mutes population always feels helpless when they are not understood by others and vice versa. This is a big humanitarian problem and needs localised solution. To solve this problem, this study implements a convolutional neural network (CNN), convolutional-based attention module (CBAM) to recognise Malaysian Sign Language (MSL) from images. Two different experiments were conducted for MSL signs, using CBAM-2DResNet (2-Dimensional Residual Network) implementing "Within Blocks" and "Before Classifier" methods. Various metrics such as the accuracy, loss, precision, recall, F1-score, confusion matrix, and training time are recorded to evaluate the models' efficiency. The experimental results showed that CBAM-ResNet models achieved a good performance in MSL signs recognition tasks, with accuracy rates of over 90% through a little of variations. The CBAM-ResNet "Before Classifier" models are more efficient than "Within Blocks" CBAM-ResNet models. Thus, the best trained model of CBAM-2DResNet is chosen to develop a real-time sign recognition system for translating from sign language to text and from text to sign language in an easy way of communication between deaf-mutes and other people. All experiment results indicated that the "Before Classifier" of CBAMResNet models is more efficient in recognising MSL and it is worth for future research.

Matched MeSH terms: Computer Systems
Infrared tomography: data distribution system and software development for real-time velocity measurement

Abdul Rahim R, Pang JF, Chan KS, Leong LC, Sulaiman S, Abdul Manaf MS

ISA Trans, 2007 Apr;46(2):131-45.
PMID: 17367791

The data distribution system of this project is divided into two types, which are a Two-PC Image Reconstruction System and a Two-PC Velocity Measurement System. Each data distribution system is investigated to see whether the results' refreshing rate of the corresponding measurement can be greater than the rate obtained by using a single computer in the same measurement system for each application. Each system has its own flow control protocol for controlling how data is distributed within the system in order to speed up the data processing time. This can be done if two PCs work in parallel. The challenge of this project is to define the data flow process and critical timing during data packaging, transferring and extracting in between PCs. If a single computer is used as a data processing unit, a longer time is needed to produce a measurement result. This insufficient real-time result will cause problems in a feedback control process when applying the system in industrial plants. To increase the refreshing rate of the measurement result, an investigation on a data distribution system is performed to replace the existing data processing unit.

Matched MeSH terms: Computer Systems
Hierarchical control strategy for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions

Naderipour A, Abdul-Malek Z, Ramachandaramurthy VK, Kalam A, Miveh MR

ISA Trans, 2019 Nov;94:352-369.
PMID: 31078293 DOI: 10.1016/j.isatra.2019.04.025

This paper proposes an improved hierarchical control strategy consists of a primary and a secondary layer for a three-phase 4-wire microgrid under unbalanced and nonlinear load conditions. The primary layer is comprised of a multi-loop control strategy to provide balanced output voltages, a harmonic compensator to reduce the total harmonic distortion (THD), and a droop-based scheme to achieve an accurate power sharing. At the secondary control layer, a reactive power compensator and a frequency restoration loop are designed to improve the accuracy of reactive power sharing and to restore the frequency deviation, respectively. Simulation studies and practical performance are carried out using the DIgSILENT Power Factory software and laboratory testing, to verify the effectiveness of the control strategy in both islanded and grid-connected mode. Zero reactive power sharing error and zero frequency steady-state error have given this control strategy an edge over the conventional control scheme. Furthermore, the proposed scheme presented outstanding voltage control performance, such as fast transient response and low voltage THD. The superiority of the proposed control strategy over the conventional filter-based control scheme is confirmed by the 2 line cycles decrease in the transient response. Additionally, the voltage THDs in islanded mode are reduced from above 5.1% to lower than 2.7% with the proposed control strategy under nonlinear load conditions. The current THD is also reduced from above 21% to lower than 2.4% in the connection point of the microgrid with the offered control scheme in the grid-connected mode.

Matched MeSH terms: Computer Systems

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