Document Type : Original Article

Authors

1 Department of Electrical Engineering, Razi University, Kermanshah, Iran.

2 Department of Energy Technology, Aalborg University, Esbjerg, Denmark.

Abstract

The expansion of renewable energy sources (RESs (and advances in power electronics have been led to more attention being paid to DC microgrids (DCMGs). DCMGs enable the exploitation of all renewable energy potentials. Along with the advantages of RESs and DCMGs, the use of RESs is associated with the challenges of absence or lack of inherent inertia. Inertia in the DCMGs plays an important role in reducing voltage changes under destructive events such as load change and power change. Therefore, by applying energy storage systems (ESSs) in DCMGs, and inertia emulation the mentioned challenges can be overcome. The proposed control scheme is implemented based on the concept of the virtual supercapacitor in the inner control loop of the ESS interface dual-half-bridge (DHB) converter with DCMG to emulate the inertia. Due to the high efficiency, electrical insulation, inherent soft switching, and the need for a smaller filter, the DHB converter has been used. Finally, a DCMG is simulated in MATLAB / Simulink. The simulation results show the efficiency and flexibility of the proposed scheme in terms of inertia emulation.

Keywords

[1] Dreidy, M., Mokhlis, H., and Mekhilef, S. (2017). Inertia response and frequency control techniques for renewable energy sources: A review. Renewable and sustainable energy reviews, Vol. 69, pp. 144-155.
[2] Yi, Z., Zhao, X., Shi, D., Duan, J., Xiang, Y., and Wang, Z. (2019). Accurate power sharing and synthetic inertia control for dc building micro-grids with guaranteed performance. IEEE Access, Vol. 7, pp. 63698-63708.
[3] Wu, W., Chen, Y., Luo, A., Zhou, L., Zhou, X., Yang, L., ... and Guerrero, J.M. (2016). A virtual inertia control strategy for DC micro-grids analogized with virtual synchronous machines.IEEE Transactions on Industrial Electronics, Vol. 64, No 7, pp. 6005-6016.
[4] Samanta, S., Mishra, J.P., and Roy, B.K. (2018). Virtual DC machine: an inertia emulation and control technique for a bidirectional DC–DC converter in a DC micro-grid. IET Electric Power Applications, Vol. 12, No 6, pp. 874-884.
[5] Pishbahar, H., Moradi CheshmehBeigi, H., Piri Yengijeh, N., and Bagheri, Shokoofeh (2021). Inertia emulation with incorporating the concept of virtual compounded DC machine and bidirectional DC–DC converter for DC micro-grid in islanded mode. IET Renewable Power Generation, Vol. 15, pp. 1812-1825.
[6] Samanta, S., Mishra, J.P., and Roy, B.K. (2019). Implementation of a virtual inertia control for inertia enhancement of a dc micro-grid under both grid connected and isolated operation. Computers and Electrical Engineering, Vol. 76, pp. 283-298.
[7] Zhu, X., Meng, F., Xie, Z., and Yue, Y. (2019). An inertia and damping control method of DC–DC converter in DC micro-grids. IEEE Transactions on Energy Conversion, Vol. 35, No 2, pp. 799-807.
[8] Zhu, X., Cai, J., Yan, Q., Chen, J., and Wang, X. (2015). Virtual inertia control of wind-battery-based islanded DC. Int. Conf. Renewable power Generation (RPG). Beijing, China.
[9] Zhi, N., Ding, K., Du, L., and Zhang, H. (2020). An SOC-based virtual DC machine control for distributed storage systems in DC micro-grids. IEEE Transactions on Energy Conversion, Vol. 35, No 3, pp. 1411-1420.
[10] Jami, M., Shafiee, Q., Gholami, M., and Bevrani, H. (2020). Control of a super-capacitor energy storage system to mimic inertia and transient response improvement of a direct current micro-grid. Journal of Energy Storage, Vol. 32, pp. 101788.
[11] Molina, M.G. (2017). Energy storage and power electronics technologies: A strong combination to empower the transformation to the smart grid. Proceedings of the IEEE, Vol. 105, No 11, pp. 2191-2219.
[12] Pan, X., Li, H., Liu, Y., Zhao, T., Ju, C., and Rathore, A.K. (2019). An overview and comprehensive comparative evaluation of current-fed-isolated-bidirectional DC/DC converter. IEEE Transactions on Power Electronics, vol. 35, No 3, p. 2737-2763.