First Order Integral Sliding Mode Control for Active and Reactive Current of A Multilevel Inverter Based Distributed Generation Unit

Abstract. This paper presents an innovative control scheme for Distributed Generation Systems, DGS, using an efficient version of the first order Sliding Mode Control, SMC. The control law of the SMC is modified in order to improve the tracking and reduce the chattering over the conventional SMC. The modification is focused on the definition of the sliding manifold, sliding surface, which contains an integral term of the error not a differential term like the conventional SMC. The proposed control scheme is applied to a multilevel diode clamped inverter based Distributed Generation Unit, DGU. The proposed control scheme is developed to control the active and reactive currents injected or absorbed by the power grid. Simulation results are provided to prove the viability of the proposed formulation and practicality of the presented sliding mode controller for the distributed generation system

Journal Staff

This paper discusses the effect of high level multi-tone acoustic excitation on the acoustic properties of perforates. It is based on a large experimental study of the nonlinear properties of these types of samples without mean grazing or bias flow. Compared to previously published results the present investigation concentrates on the effect of multiple harmonics. It is known from previous studies that high level acoustic excitation at one frequency will change the acoustic impedance of perforates at other frequencies, thereby changing the boundary condition seen by the acoustic waves. This effect could be used to change the impedance boundary conditions and for instance increase the absorption. It could obviously also pose a problem for the correct modelling of sound transmission through ducts lined with such impedance surfaces. Experimental results are compared to a quasi-stationary model. The effect of the combination of frequency components and phase in the excitation signal is studied.QC 20131030</p

Control and estimation techniques applied to smart microgrids : a review

DATA AVAILABILITY : No data was used for the research described in the article.The performance of microgrid operation requires hierarchical control and estimation schemes that coordinate and monitor the system dynamics within the expected manipulated and control variables. Smart grid technologies possess innovative tools and frameworks to model the dynamic behaviour of microgrids regardless of their types, structures, etc. Various control and estimation technologies are reviewed for developing dynamic models of smart microgrids. The hierarchical system of a microgrid control consists of three architectural layers, primary, secondary and tertiary, which need to be supported by real-time monitoring and measurement environment of the system variables and parameters. Various control and estimation schemes have been devised to handle the dynamic performance of microgrids in the function of control layers requirement. Firstly, control schemes in the innovative grid environment are evaluated to understand the dynamics of the developed technologies. Six control technologies, linear, non-linear, robust, predictive, intelligent and adaptive, are mainly used to model the control design within the layer(s) regardless of the types of microgrids. Secondly, the estimation technologies are evaluated based on the state of variables, locations and modelling of microgrids that can efficiently support the performance of the controllers and operating microgrids. Finally, a future vision for designing hierarchical and architectural control techniques for the optimal operation of intelligent microgrids is also provided. Therefore, this study will serve as a fundamental conceptual framework to select a perfect optimal design modelling strategy and policy-making decisions to control, monitor and protect the innovative electrical network.http://www.elsevier.com/locate/rserhj2023Electrical, Electronic and Computer Engineerin

Analysis of acoustic networks including cavities by means of a linear finite volume method

[EN] A procedure allowing for the analysis of complex acoustic networks, including three-dimensional cavities described in terms of zero-dimensional equivalent elements, is presented and validated. The procedure is based on the linearization of the finite volume method often used in gas-dynamics, which is translated into an acoustic network comprising multi-ports accounting for mass exchanges between the finite volumes, and equivalent 2-ports describing momentum exchange across the volume surfaces. The application of the concept to a one-dimensional case shows that it actually converges to the exact analytical solution when a sufficiently large number of volumes are considered. This has allowed the formulation of an objective criterion for the choice of a mesh providing results with a prefixed error up to a certain Helmholtz number, which has been generalized to three-dimensional cases. The procedure is then applied to simple but relevant three-dimensional geometries in the absence of a mean flow, showing good agreement with experimental and other computational results.This work has been partially supported by Ricardo Software, and by Ministerio de Ciencia e Innovacion through Grant DPI2009-14290. The authors thank Dr. F.D. Denia for his kind computational assistance.Torregrosa, AJ.; Broatch, A.; Gil, A.; Moreno Martínez, D. (2012). Analysis of acoustic networks including cavities by means of a linear finite volume method. Journal of Sound and Vibration. 331(20):4575-4586. https://doi.org/10.1016/j.jsv.2012.05.023S457545863312

Modular multilevel converter-based microgrid : a critical review

Recently, the Modular Multilevel Converter (MMC) has drawn significant attention due to its diverse merits and its applicability to a wide range of medium to high-power applications. The growing interest in the MMC can be attributed to its attractive features such as modularity, reliability, and high voltage capability. Significant research has been conducted on the MMC over the last few years to develop its operation and control in various applications. However, the application of MMCs in microgrids remains a largely unexplored topic. Therefore, this paper aims to address this research gap by offering an in-depth review of the latest developments concerning circuit topologies, control schemes, and fault-tolerance strategies of MMC within microgrid applications. This comprehensive review not only provides a synthesized overview of the current state of the art but also paves the way for future investigations in this promising field. The outcomes from this study are expected to stimulate further advancements in MMC applications in microgrid systems, thus contributing to the continuous improvement and evolution of microgrids.University of Sharjahhttps://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6287639Electrical, Electronic and Computer Engineerin

Relation of Asthma Control with Quality of Life among a Sample of Egyptian Asthmatic School Children

BACKGROUND: Asthma is considered a chronic health illness that not only resulted in physical symptoms but also emotional effects. It is; therefore, so important to assess the quality of life of asthmatic patients besides their level of disease control. AIM: To determine the correlation of asthma control with the health-related quality of life (HRQOL) of asthmatic children in Egypt. METHODS: One hundred and twenty-eight asthmatic Egyptian children were enrolled in the study. They were subjected to asthma severity grading, asthma control questionnaire (ACQ) and pediatric asthma quality of life questionnaire (PAQLQ). Studied cases were taken from 6 primary and preparatory schools, Giza governorate. RESULTS: The mean child control score was significantly higher in not well-controlled asthmatics compared to well-controlled asthmatics (p &lt; 0.005). The not well controlled asthmatic children showed significantly lower activity limitation score, symptoms score, and overall asthmatic score compared to controlled asthmatic children (p &lt; 0.05). The severity of asthma shows significant positive correlation with symptoms score, emotional function score and overall asthmatic score (p &lt; 0.05). CONCLUSION: The quality of life for the asthmatic children is strongly correlated with the level of asthma control and severity

Quenching of acoustic bandgaps by flow noise

Copyright (2009) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics along with the following message: The following article appeared in Appl. Phys. Lett. 94, 134104 (2009) and may be found at http://dx.doi.org/10.1063/1.3111797. Authors own version of final article on e-print serversWe report an experimental study of acoustic effects produced by wind impinging on noise barriers based on two-dimensional sonic crystals with square symmetry. We found that the attenuation strength of sonic-crystal bandgaps decreases for increasing values of flow speed. A quenching of the acoustic bandgap appears at a certain speed value that depends of the barrier filling ratio. For increasing values of flow speed, the data indicate that the barrier becomes a sound source because of its interaction with the wind. We conclude that flow noise should be taken into account in designing acoustic barriers based on sonic crystals.This work was supported by the Spanish Agency of International Cooperation (AECI), the Spanish Ministry of Science and Innovation (MICIIN), and the Spanish Ministry of Public Works (MF). J.S.-D. acknowledges useful conversations with A. Broatch.Elnady, T.; Elsabbagh, A.; Akl, W.; Mohamady, O.; Garcia Chocano, VM.; Torrent Martí, D.; Cervera Moreno, FS.... (2009). Quenching of acoustic bandgaps by flow noise. Applied Physics Letters. 94(13). doi:10.1063/1.3111797S9413Sánchez-Pérez, J. V., Caballero, D., Mártinez-Sala, R., Rubio, C., Sánchez-Dehesa, J., Meseguer, F., … Gálvez, F. (1998). Sound Attenuation by a Two-Dimensional Array of Rigid Cylinders. Physical Review Letters, 80(24), 5325-5328. doi:10.1103/physrevlett.80.5325Rubio, C., Caballero, D., Sanchez-Perez, J. V., Martinez-Sala, R., Sanchez-Dehesa, J., Meseguer, F., & Cervera, F. (1999). The existence of full gaps and deaf bands in two-dimensional sonic crystals. Journal of Lightwave Technology, 17(11), 2202-2207. doi:10.1109/50.803012Caballero, D., Sánchez-Dehesa, J., Rubio, C., Mártinez-Sala, R., Sánchez-Pérez, J. V., Meseguer, F., & Llinares, J. (1999). Large two-dimensional sonic band gaps. Physical Review E, 60(6), R6316-R6319. doi:10.1103/physreve.60.r6316Caballero, D., Sánchez-Dehesa, J., Martínez-Sala, R., Rubio, C., Sánchez-Pérez, J. V., Sanchis, L., & Meseguer, F. (2001). Suzuki phase in two-dimensional sonic crystals. Physical Review B, 64(6). doi:10.1103/physrevb.64.064303Chen, Y.-Y., & Ye, Z. (2001). Acoustic Attenuation by Two-Dimensional Arrays of Rigid Cylinders. Physical Review Letters, 87(18). doi:10.1103/physrevlett.87.184301Sanchez-Perez, J. V., Rubio, C., Martinez-Sala, R., Sanchez-Grandia, R., & Gomez, V. (2002). Acoustic barriers based on periodic arrays of scatterers. Applied Physics Letters, 81(27), 5240-5242. doi:10.1063/1.1533112Goffaux, C., Maseri, F., Vasseur, J. O., Djafari-Rouhani, B., & Lambin, P. (2003). Measurements and calculations of the sound attenuation by a phononic band gap structure suitable for an insulating partition application. Applied Physics Letters, 83(2), 281-283. doi:10.1063/1.1592016Goffaux, C., & Vigneron, J. P. (2001). Theoretical study of a tunable phononic band gap system. Physical Review B, 64(7). doi:10.1103/physrevb.64.075118Zhong, L., Wu, F., Zhang, X., Zhong, H., & Zhong, S. (2005). Effects of orientation and symmetry of rods on the complete acoustic band gap in two-dimensional periodic solid/gas systems. Physics Letters A, 339(1-2), 164-170. doi:10.1016/j.physleta.2005.03.025Umnova, O., Attenborough, K., & Linton, C. M. (2006). Effects of porous covering on sound attenuation by periodic arrays of cylinders. The Journal of the Acoustical Society of America, 119(1), 278-284. doi:10.1121/1.2133715Martínez-Sala, R., Rubio, C., García-Raffi, L. M., Sánchez-Pérez, J. V., Sánchez-Pérez, E. A., & Llinares, J. (2006). Control of noise by trees arranged like sonic crystals. Journal of Sound and Vibration, 291(1-2), 100-106. doi:10.1016/j.jsv.2005.05.030Sanchis, L., Håkansson, A., Cervera, F., & Sánchez-Dehesa, J. (2003). Acoustic interferometers based on two-dimensional arrays of rigid cylinders in air. Physical Review B, 67(3). doi:10.1103/physrevb.67.03542