{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T02:02:36Z","timestamp":1760148156641,"version":"build-2065373602"},"reference-count":24,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2023,4,5]],"date-time":"2023-04-05T00:00:00Z","timestamp":1680652800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of Botswana"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>This article proposes a novel equivalent control method for voltage source inverters (VSI) with disturbance observers (DOB) to support the symmetric and asymmetric voltage requirements of a micro-grid (MG) while also matching the MG output power requirements. The method leverages the degrees of freedom (DOF) of the VSI under symmetric and asymmetric MG voltage conditions by utilizing the mean-point voltage of the MG, which is often overlooked in literature studies due to this being grounded. The method enables the three-phase inverter to generate voltages as needed by the MG inconsistently due to changing loads in the MG circuits or phases. The method is also insensitive to disturbances because of the DOB, being part of the controller. The proposed method is validated under both the balance and imbalance voltage demands of the MG. The mean voltage of the MG is used as a set-point to be corroborated as a mean voltage at the inverter\u2019s output, in addition to active-reactive power references. The novel model is developed by augmenting the new, mean-point voltage as part of the system dynamics. The proposed method is simulated in MATLAB\/Simulink\u00ae and is verified for its hardiness and effectiveness.<\/jats:p>","DOI":"10.3390\/sym15040865","type":"journal-article","created":{"date-parts":[[2023,4,5]],"date-time":"2023-04-05T05:42:44Z","timestamp":1680673364000},"page":"865","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Utilizing Full Degrees of Freedom of Control in Voltage Source Inverters to Support Micro-Grid with Symmetric and Asymmetric Voltage Requirements"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0018-3455","authenticated-orcid":false,"given":"Akhtar","family":"Rasool","sequence":"first","affiliation":[{"name":"Department of Electrical Engineering, University of Botswana, Gaborone UB 0061, Botswana"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4105-2483","authenticated-orcid":false,"given":"Fiaz","family":"Ahmad","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, Air University, Islamabad 44000, Pakistan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0335-298X","authenticated-orcid":false,"given":"Muhammad Salman","family":"Fakhar","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5038-9072","authenticated-orcid":false,"given":"Syed Abdul Rahman","family":"Kashif","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, University of Engineering and Technology, Lahore 54000, Pakistan"}]},{"given":"Edwin","family":"Matlotse","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering, University of Botswana, Gaborone UB 0061, Botswana"}]}],"member":"1968","published-online":{"date-parts":[[2023,4,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Bharothu, J.N., Sridhar, M., and Rao, R.S. (2014, January 19\u201320). A literature survey report on Smart Grid technologies. Proceedings of the IEEE International Conference on Smart Electric Grid (ISEG), Guntur, India.","DOI":"10.1109\/ISEG.2014.7005601"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Ekanayake, J.B., Jenkins, N., Liyanage, K., Wu, J., and Yokoyama, A. (2012). Smart Grid: Technology and Applications, John Wiley & Sons.","DOI":"10.1002\/9781119968696"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"2659","DOI":"10.1016\/j.rser.2017.06.071","article-title":"Distribution system state estimation-A step towards smart grid","volume":"81","author":"Ahmad","year":"2018","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Kaviri, S.M., Pahlevani, M., Jain, P., and Bakhshai, A. (2017, January 17\u201320). A review of AC microgrid control methods. Proceedings of the 8th IEEE International Symposium on Power Electronics for Distributed Generation Systems (PEDG), Florian\u00f3polis, Brazil.","DOI":"10.1109\/PEDG.2017.7972498"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"562","DOI":"10.1016\/j.rser.2015.03.031","article-title":"A survey on the contributions of power electronics to smart grid systems","volume":"47","author":"Colak","year":"2015","journal-title":"Renew. Sustain. Energy Rev."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Teodorescu, R., Liserre, M., and Rodriguez, P. (2011). Grid Converters for Photovoltaic and Wind Power Systems, John Wiley & Sons.","DOI":"10.1002\/9780470667057"},{"key":"ref_7","first-page":"455","article-title":"Power electronic systems as a crucial part of Smart Grid infrastructure\u2014A survey","volume":"59","author":"Benysek","year":"2011","journal-title":"Bull. Pol. Acad. Sci. Tech. Sci."},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Arbab-Zavar, B., Palacios-Garcia, E.J., Vasquez, J.C., and Guerrero, J.M. (2019). Smart Inverters for Microgrid Applications: A Review. Energies, 12.","DOI":"10.3390\/en12050840"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Jiang, H., Cao, S., Soh, C.B., and Wei, F. (2021, January 22\u201324). Unbalanced load modeling and control in microgrid with isolation transformer. Proceedings of the IEEE International Conference on Electrical Drives & Power Electronics (EDPE), Dubrovnik, Croatia.","DOI":"10.1109\/EDPE53134.2021.9604101"},{"key":"ref_10","first-page":"562","article-title":"Control strategy for grid connected inverters under unbalanced network conditions-A DOb based decoupled current approach","volume":"47","author":"Padmanaban","year":"2017","journal-title":"Energies"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Li-Jun, J., Miao-Miao, J., Guang-Yao, Y., Yi-Fan, C., Rong-Zheng, L., Hai-Peng, Z., and Ke, Z. (2015, January 15\u201317). Unbalanced control of grid-side converter based on DSOGI-PLL. Proceedings of the IEEE 10th Conference on Industrial Electronics and Applications (ICIEA), Auckland, New Zealand.","DOI":"10.1109\/ICIEA.2015.7334279"},{"key":"ref_12","unstructured":"Suul, J.A. (2012). Control of Grid Integrated Voltage Source Converters under Unbalanced Conditions: Development of an on-Line Frequency-Adaptive Virtual Flux-Based Approach. [Ph.D. Thesis, Norwegian University of Science and Technology]."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Puranik, S., Keyhani, A., and Chatterjee, A. (2012). Smart Power Grids 2011, Springer.","DOI":"10.1007\/978-3-642-21578-0"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"562","DOI":"10.1109\/TIA.1985.349711","article-title":"Current control of VSI-PWM inverters","volume":"3","author":"Brod","year":"1985","journal-title":"IEEE Trans. Ind. Appl."},{"key":"ref_15","unstructured":"Tenca, P., and Lipo, T.A. (April, January 31). Synthesis of desired AC line currents in current-sourced DC-AC converters. Proceedings of the IEEE Second International Conference on Power Electronics, Machines and Drives (PEMD), Edinburgh, UK."},{"key":"ref_16","unstructured":"Milosevic, M. (November, January 29). Decoupling control of d and q current components in three-phase voltage source inverter. Proceedings of the IEEE Power Systems Conference and Exposition (PSCE), Atlanta, GA, USA."},{"key":"ref_17","doi-asserted-by":"crossref","unstructured":"Sowmmiya, U., and Jamuna, V. (2011, January 3\u20135). Voltage control scheme for three phase SVM inverter fed induction motor drive systems. Proceedings of the IEEE 1st International Conference on Electrical Energy Systems (ICEES), Chennai, India.","DOI":"10.1109\/ICEES.2011.5725329"},{"key":"ref_18","unstructured":"Sabanovic, A., Ohnishi, K., and Sabanovic, N. (1993, January 19\u201321). Control of PWM three phase converters: A sliding mode approach. Proceedings of the Conference Record of Power Conversion Conference, Yokohama, Japan."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1108\/WJE-10-2016-0118","article-title":"A robust cascaded controller for DC-DC Boost and Cuk converters","volume":"14","author":"Fiaz","year":"2017","journal-title":"World J. Eng."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"1687","DOI":"10.1049\/iet-pel.2019.1080","article-title":"Unbalance mitigation strategies in microgrids","volume":"13","author":"Vijay","year":"2020","journal-title":"IET Power Electron."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"20","DOI":"10.1109\/TSG.2021.3108677","article-title":"Distributed predictive secondary control for imbalance sharing in AC microgrids","volume":"13","author":"Donoso","year":"2022","journal-title":"IEEE Trans. Smart Grid"},{"key":"ref_22","doi-asserted-by":"crossref","unstructured":"Utkin, V., Guldner, J., and Shi, J. (2017). Sliding Mode Control in Electro-Mechanical Systems, Taylor & Francis, CRC Press. [3rd ed.].","DOI":"10.1201\/9781420065619"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e12389","DOI":"10.1002\/2050-7038.12389","article-title":"Three-phase converter power control under grid imbalance with consideration of instantaneous power components limitation","volume":"30","author":"Wodyk","year":"2020","journal-title":"Int. Trans. Electr. Energy Syst."},{"key":"ref_24","unstructured":"Rasool, A. (2017). Control of Three Phase Converters as Source for Microgrid. [Ph.D. Thesis, Sabanc\u0131 University]."}],"container-title":["Symmetry"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-8994\/15\/4\/865\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T19:10:25Z","timestamp":1760123425000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-8994\/15\/4\/865"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,4,5]]},"references-count":24,"journal-issue":{"issue":"4","published-online":{"date-parts":[[2023,4]]}},"alternative-id":["sym15040865"],"URL":"https:\/\/doi.org\/10.3390\/sym15040865","relation":{},"ISSN":["2073-8994"],"issn-type":[{"type":"electronic","value":"2073-8994"}],"subject":[],"published":{"date-parts":[[2023,4,5]]}}}