In recent years, the global energy industry has been experiencing a remarkable growth of distributed generators, which are mostly based on power electronics grid interfaces. This phenomenon has led to the development of many different techniques to allow the parallel operation of these dispersed sources without communication links. Most of the proposed techniques aim at emulating the behavior of synchronous generators, as it is the case of the droop control, virtual synchronous generator and synchronverter techniques. The synchronverter algorithm has increased the interest of many researchers due to its ability to perform autonomous power sharing and the possibility of adjusting its virtual inertia to enhance the dynamic response. Several implementation approaches of synchronverters have been proposed in literature. However, in most cases, the synchronverter performance is only evaluated under normal grid voltage conditions. This paper proposes a positive–negative sequence synchronverter technique for three-phase voltage source converters connected to unbalanced grids. This method consists in separating the power control in positive and negative sequence components to improve the converter behavior under both unbalanced grid voltages and unbalanced voltage sags. Simulation and experimental results validate the proposed method highlighting its capability of limiting the converter output current, reducing power oscillations and avoiding undesired shutdowns.
This is a preview of subscription content, access via your institution.
Buy single article
Instant access to the full article PDF.
Tax calculation will be finalised during checkout.
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
Tax calculation will be finalised during checkout.
Bevrani, H., Ghosh, A., & Ledwich, G. (2010). Renewable energy sources and frequency regulation: Survey and new perspectives. IET Renewable Power Generation, 4(5), 438–457.
Chen, M., Xiao, X., Yuan, C., Tao, S. (2017). Flexible power control of virtual synchronous generators under unbalanced grid voltage conditions. 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, pp. 2881-2888.
Cupertino, A. F., Xavier, L. S., & Brito, E. M. S. (2019). Benchmarking of power control strategies for photovoltaic systems under unbalanced conditions. International Journal of Electrical Power and Energy Systems., 106, 335–345.
de Souza, W. F., Severo-Mendes, M. A., & Lopes, L. A. C. (2015). Power sharing control strategies for a three-phase microgrid in different operating condition with droop control and damping factor investigation. IET Renewable Power Generation, 9(7), 831–839.
Dugan, R. C., & McGranaghan, M. F. (1996). Electrical power systems quality (2nd ed.). McGraw-Hill: New York.
Ferreira R. V., Silva S. M., Brandao D. I., et al. (2016). Single-phase synchronverter for residential PV power systems. 17th International Conference on Harmonics and Quality of Power (ICHQP), pp. 861–866.
Fortescue C. L. (1918). Method of symmetrical co-ordinates applied to the solution of polyphase networks. 34th Annual Convention of the American Institute of Electrical Engineers, Atlantic City, N. J.
Hoke, A., et al. (2018). Setting the smart solar standard: collaborations between Hawaiian electric and the national renewable energy laboratory. IEEE Power and Energy Magazine, 16(6), 18–29.
Hu Y., McKenzie H., Chen Z. (2008). Voltage source converters in distributed generation systems, 3rd International Conference on Electric Utility Deregulation and Restructuring and Power Technologies, Nanjing, pp. 2775–2780.
IEEE standard. (2018). IEEE standard for interconnection and interoperability of distributed energy resources with associated electric power systems interfaces, in: IEEE Std 1547–2018 (Revision of IEEE Std 1547–2003), pp.1–138.
La Gatta, P. O., Passos Filho, J. A., & Pereira, J. L. R. (2019). Tools for handling steady-state under-frequency regulation in isolated microgrids. IET Renewable Power Generation, 13(4), 609–617.
Li, Z., Zang, C., Zeng, P., et al. (2017). Control of a grid-forming inverter based on sliding-mode and mixed H2/H∞ control. IEEE Transactions on Industrial Electronics, 64(5), 3862–3872.
Liu, L. G., Zhu, K., Wang, W. (2018). An improved control strategy of virtual synchronous generator under unbalanced conditions, 2018 IEEE 4th Southern Power Electronics Conference (SPEC), Singapore, Singapore, pp. 1-6.
Ma Z., Zhong Q. C., Yan J. D. (2012). Synchronverter-based control strategies for three-phase pwm rectifiers, 7th IEEE Conference on Industrial Electronics and Applications (ICIEA), pp. 225–230.
McGranaghan, M. F., Mueller, D. R., & Samotyj, M. J. (1993). Voltage sags in industrial systems. IEEE Transactions on Industry Applications, 29(2), 397–403.
Mishra, S., Pullaguram, D., Buragappu, S. A., et al. (2016). Single-phase synchronverter for a grid-connected roof top photovoltaic system. IET Renewable Power Generation, 10(8), 1187–1194.
Planas, E., Gil-de-Muro, A., Andreu, J., et al. (2013). Design and implementation of a droop control in d-q frame for islanded microgrids. IET Renewable Power Generation, 7(5), 458–474.
Rodriguez, P., Pou, J., Bergas, J., et al. (2007). Decoupled double synchronous reference frame PLL for power converters control. IEEE Transactions on Power Electronics, 22(2), 584–592.
Teodorescu, R., Liserre, M., Rodriguez, P. (2007). Grid requirements for PV’. Grid converters for photovoltaic and wind power systems, IEEE.
Wang, C., Wu, J., Yang, D., Zhao, J. (2017). Suppressing power oscillation based on VSG. 2017 IEEE 2nd Information Technology, Networking, Electronic and Automation Control Conference (ITNEC), Chengdu, pp. 336-339.
Wang, M., Li, H., Li, L. (2018). Fault through technique of synchronverter based on voltage feedforward compensation, 2018 International Conference on Power System Technology (POWERCON), Guangzhou, pp. 2056–2061.
Wang, X., Chen, L., Sun, D., Zhang, L., & Nian, H. (2019). A Modified self-synchronized synchronverter in unbalanced power grids with balanced currents and restrained power ripples. Energies, 12, 923.
Yang, Y., Wang, H., & Blaabjerg, F. (2014). Reactive power injection strategies for single-phase photovoltaic systems considering grid requirements. IEEE Transactions on Industry Applications, 50(6), 4065–4076.
Yazdani, A., & Iravani, R. (2010). Voltage-sourced converters in power systems: Modeling, control, and applications. Amsterdam: Wiley.
Yu, Y., & Hu, X. (2019). Active disturbance rejection control strategy for grid-connected photovoltaic inverter based on virtual synchronous generator. IEEE Access, 7, 17328–17336.
Zhang C. H., Zhong Q. C., Meng J. S., et al. (2013). An improved synchronverter model and its dynamic behaviour comparison with synchronous generator, 2nd IET Renewable Power Generation Conference, pp. 1–4.
Zhao, X., Guerrero, J. M., Savaghebi, M., et al. (2017). Low-voltage ride-through operation of power converters in grid-interactive microgrids by using negative-sequence droop control. IEEE Transactions on Power Electronics, 32(4), 3128–3142.
Zheng, T., Chen, L., Guo, Y., & Mei, S. (2018). Comprehensive control strategy of virtual synchronous generator under unbalanced voltage conditions. IET Generation, Transmission and Distribution, 12(7), 1621–2163.
Zheng, T., Chen, L., Zhang, H., Chen, T., Mei, S. (2015). Control strategy for suppressing power oscillation of virtual synchronous generator under unbalanced grid voltage, International Conference on Renewable Power Generation (RPG 2015), Beijing, pp. 1–5.
Zheng, X., Wang, C., & Pang, S. (2019a). Injecting positive-sequence current virtual synchronous generator control under unbalanced grid. IET Renewable Power Generation, 13(1), 165–170.
Zheng, X., Wang, C., Pang, S. (2019b). Injecting positive-sequence current virtual synchronous generator control under unbalanced grid, in IET Renewable Power Generation, vol. 13, no. 1, pp. 165–170.
Zhong, Q., & Konstantopoulos, G. C. (2017). Current-limiting droop control of grid-connected inverters. IEEE Transactions on Industrial Electronics, 64(7), 5963–5973.
Zhong, Q. C., Nguyen, P. L., Ma, Z., et al. (2014) Self-synchronized synchronverters: Inverters without a dedicated synchronization unit, IEEE Transactions on Power Electronics, 29(2), pp. 617–630.
Zhong, Q., & Weiss, G. (2011). Synchronverters: Inverters that mimic synchronous generators. IEEE Transactions on Industrial Electronics, 58(4), 1259–1267.
Zhong, Q., & Zeng, Y. (2016). Universal droop control of inverters with different types of output impedance. IEEE Access, 4, 702–712.
This work has been supported by the Brazilian agencies CAPES, FAPEMIG (APQ-02518-16) and CNPq (420850/2016-3). The authors also would like to thank the Federal Institute of Minas Gerais, Brazil.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Ferreira, R.V., Silva, S.M. & Brandao, D.I. Positive–Negative Sequence Synchronverter for Unbalanced Voltage in AC Grids. J Control Autom Electr Syst (2021). https://doi.org/10.1007/s40313-021-00690-4
- Unbalanced grid
- Positive–negative sequence
- Grid-connected converter