The scientific objective of this study is to demonstrate how a hybrid photovoltaic-grid-generator microsystem responds under transient regime to varying loads and grid disconnection/reconnection. The object of the research was realized by acquiring the electrical magnitudes from the three PV systems (25 kW, 40 kW, and 60 kW) connected to the grid and the consumer (on-grid), during the technological process where the load fluctuated uncontrollably. Similar recordings were also made for the transient regime caused by the grid disconnection, diesel generator activation (450 kVA), its synchronization with PV systems, power supply to receivers, and grid voltage restoration after diesel generator shutdown. Analysis of the data focused on power supply continuity, voltage stability, and frequency variations. Findings indicated that on-grid photovoltaic systems had a 7.9% maximum voltage deviation from the standard value (230 V) and a frequency variation within ±1%. In the transient period caused by the grid disconnection and reconnection, a brief period with supply interruption was noted. This study contributes to the understanding of hybrid system behavior during transient regimes.

Ameen, A. M., Pasupuleti, J., & Khatib, T. (2015). Replacement model for hybrid Photovoltaic/Diesel generator/Battery system’s components with typical control strategy. In: Proceedings of the 2015 IEEE Student Conference on Research and Development (SCOReD). https://doi.org/10.1109/scored.2015.7449328

Atănăsoae, P., Pentiuc, R. D., Milici, D. L., et al. (2019). The Cost-Benefit Analysis of the Electricity Production from Small Scale Renewable Energy Sources in the Conditions of Romania. Procedia Manufacturing, 32, 385–389. https://doi.org/10.1016/j.promfg.2019.02.230

Averbukh М. А., Zhilin Е. V., & Prokopishin, D. I. (2018). Electric Power Loss Minimization in Power Supply Systems for the Suburban Houses. Problemele Energeticii Regionale, 2, 31–38. https://doi.org/10.5281/zenodo.1343394

Babatunde, O. M., Munda, J. L., & Hamam, Y. (2020). A Comprehensive State-of-the-Art Survey on Hybrid Renewable Energy System Operations and Planning. IEEE Access, 8, 75313–75346. https://doi.org/10.1109/access.2020.2988397

Badea, G., Felseghi, R. A, Raboaca, M. S., et al. (2016). Techno-economical Analysis of Hybrid PV-WT-Hydrogen FC System for a Residential Building with Low Power Consumption. Problemele Energeticii Regionale, 3, 78–84.

Brahim, B. (2019). Performance investigation of a hybrid PV-diesel power system for remote areas. International Journal of Energy Research, 43(2), 1019–1031. https://doi.org/10.1002/er.4301

Budiyanto, A., Kamil, M. I., Aryani, D. R., et al. (2020). Performance analysis of a hybrid natural gas generator/photovoltaic system for residential use. IOP Conference Series: Earth and Environmental Science, 599(1), 012018. https://doi.org/10.1088/1755-1315/599/1/012018

Chindris, M., Cziker, A., Anca, M., et al. (2016). Small Distributed Renewable Energy Generation for Low Voltage Distribution Networks. Problemele Energeticii Regionale, 2, 11–21.

Coban, H. H. (2023). Hydropower Planning in Combination with Batteries and Solar Energy. Sustainability, 15(13), 10002. https://doi.org/10.3390/su151310002

Das, D., Chakraborty, I., Bohre, A. K., et al. (2024). Sustainable Integration of Green Hydrogen in Renewable Energy Systems for Residential and EV Applications. International Journal of Energy Research, 2024, 1–20. https://doi.org/10.1155/2024/8258624

Dehghani, F., & Shafiyi, M. A. (2023). Integration of hybrid renewable energy sources with the power system considering their economic complementarity. IET Renewable Power Generation, 17(15), 3638–3650. https://doi.org/10.1049/rpg2.12871

EN. (1999). Voltage characteristics of electricity supplied by public distribution systems. Available online: https://fs.gongkong.com/files/technicalData/201110/2011100922385600001.pdf (accessed on 2 June 2024).

Fluke. (2024). Fluke 434-II and 435-II Power Quality and Energy Analyzers. Available online: https://www.fluke.com/en-us/product/electrical-testing/power-quality/434-435 (accessed on 24 June 2024).

Giraud, F., & Salameh, Z. M. (2007). Measurements of Harmonics Generated by an Interactive Wind/Photovoltaic Hybrid Power System. Electric Power Components and Systems, 35(7), 757–768. https://doi.org/10.1080/15325000601175132

Halabi, L. M., Mekhilef, S., Olatomiwa, L., et al. (2017). Performance analysis of hybrid PV/diesel/battery system using HOMER: A case study Sabah, Malaysia. Energy Conversion and Management, 144, 322–339. https://doi.org/10.1016/j.enconman.2017.04.070

Huang, X. J., & Bao, N. S. (2017). Modeling and simulation analysis of wind-hydro hybrid power plant. In: Proceedings of the 2nd Annual International Conference on Energy, Environmental & Sustainable Ecosystem Development (EESED 2016). https://doi.org/10.2991/eesed-16.2017.22

IEC. (2015). Testing and measurement techniques—Power quality measurement methods. Available online: https://webstore.iec.ch/en/publication/21844 (accessed on 2 June 2024).

Isakov, I., & Todorovic, I. (2021). Power production strategies for two-stage PV systems during grid faults. Solar Energy, 221, 30–45. https://doi.org/10.1016/j.solener.2021.03.085

Kemp, J. M., Millstein, D., Kim, J. H., et al. (2023). Interactions between hybrid power plant development and local transmission in congested regions. Advances in Applied Energy, 10, 100133. https://doi.org/10.1016/j.adapen.2023.100133

Khosravani, A., Safaei, E., Reynolds, M., et al. (2023). Challenges of reaching high renewable fractions in hybrid renewable energy systems. Energy Reports, 9, 1000–1017. https://doi.org/10.1016/j.egyr.2022.12.038

Manoj, D., Tomonobu, S., Atsushi, Y., et al. (2011). A Frequency-Control Approach by Photovoltaic Generator in a PV-Diesel Hybrid Power System. IEEE Transactions on Energy Conversion, 26(2), 559–571. https://doi.org/10.1109/tec.2010.2089688

Maritz, J., Gorjão, L. R., Bester, P. A., et al. (2024). Data-Driven Modeling of Frequency Dynamics Observed in Operating Microgrids: A South African University Campus Case Study. IEEE Access, 12, 14466–14473. https://doi.org/10.1109/access.2024.3357945

Martínez, J., & Medina, A. (2010). A state space model for the dynamic operation representation of small-scale wind-photovoltaic hybrid systems. Renewable Energy, 35(6), 1159–1168. https://doi.org/10.1016/j.renene.2009.11.039

Mthwecu, S., & Chowdhury, S. (2015). Solar PV/Diesel Hybrid Power System design using macroeconomic analysis. In: Proceedings of the 2015 50th International Universities Power Engineering Conference (UPEC). https://doi.org/10.1109/upec.2015.7339958

Neamt, L., Petrean, L., Chiver, O., et al. (2018). Some Considerations About Overvoltages During and After the Disconnection of a Photovoltaic Park. In: Proceedings of the 2018 IEEE 24th International Symposium for Design and Technology in Electronic Packaging (SIITME). https://doi.org/10.1109/siitme.2018.8599251

Nguyen, H. V. P., Nguyen, V. T., Vo, Q. S., et al. (2021). Enhancing effectiveness of grid-connected photovoltaic systems by using hybrid energy storage systems. Journal of Engineering Science and Technology, 16(2), 1561–1576.

ANRE. (2021). Performance standard for electricity distribution service. Official Monitor, 649(1).

Pan, W., Gao, W., & Muljadi, E. (2009). The dynamic performance and effect of hybrid renewable power system with diesel/wind/PV/battery. In: Proceedings of the 2009 International Conference on Sustainable Power Generation and Supply. https://doi.org/10.1109/supergen.2009.5348178

Priolkar, J. G., & Doolla, S. (2013). Analysis of PV-hydro isolated power systems. In: Proceedings of the 2013 Annual IEEE India Conference (INDICON). https://doi.org/10.1109/indcon.2013.6725890

Ratnata, I. W., Sumarto, S., & Saputra, W. S. (2019). Performance analysis of Pico Hydro-Solar Photovoltaic Hybrid System. In: Proceedings of the 2nd International Symposium on Materials and Electrical Engineering (ISMEE); 17 July 2019; Bandung, Indonesia.

Siddaraj, U., & Tangi, S. (2016). Integration of DG systems composed of photovoltaic and a micro-turbine in remote areas. In: Proceedings of the 2016 International Conference on Computation of Power, Energy Information and Commuincation (ICCPEIC). https://doi.org/10.1109/iccpeic.2016.7557332

Spunei, E., Piroi, I., & Piroi, F. (2022). Efficiency of a small power photovoltaic installation connected to the low voltage network. Journal of Physics: Conference Series, 2212(1), 012020. https://doi.org/10.1088/1742-6596/2212/1/012020

Spunei, E., Piroi, I., Piroi, F., et al. (2021). Examining the Performances of a Low Power Photovoltaic Installation. In: Proceedings of the 2021 12th International Symposium on Advanced Topics in Electrical Engineering (ATEE). https://doi.org/10.1109/atee52255.2021.9425231

Zhang, Y., Ma, C., Yang, Y., et al. (2021). Study on short-term optimal operation of cascade hydro-photovoltaic hybrid systems. Applied Energy, 291, 116828. https://doi.org/10.1016/j.apenergy.2021.116828