A Virtual Synchronous Machine to Support Dynamic Frequency Control in a Mini-Grid That Operates in Frequency Droop Mode

Miguel  Torres; Luiz A. C.  Lopes

doi:10.4236/epe.2013.53025

Miguel Torres, Luiz A. C. Lopes

Abstract: This paper addresses the problem of dynamic frequency control in a diesel-based mini-grid. It is shown that a virtual synchronous machine (VSM) can support dynamic frequency control by adding virtual inertia and damping to the system. However, it is found that the typical formulation of damping power does not work properly when the grid forming gen-set operates in droop mode because of the unknown stabilization value of the grid frequency. As a solution to this problem, an estimator for the stabilization frequency that works in conjunction with the damping function of the VSM is proposed. Theoretical and experimental results provide evidence of a satisfactory performance of the proposed VSM with estimator for different values of the gen-set droop factor. The estimated stabilization frequency converges in approximately 2 s and the maximum frequency deviation during the transient is reduced in 34%, on average.

Keywords: Frequency Control; Mini-Grid; Inverter; Virtual Synchronous Machine

Cite this paper: M. Torres and L. Lopes, "A Virtual Synchronous Machine to Support Dynamic Frequency Control in a Mini-Grid That Operates in Frequency Droop Mode," Energy and Power Engineering, Vol. 5 No. 3, 2013, pp. 259-265. doi: 10.4236/epe.2013.53025.

References

[1] P. Kundur, J. Paserba, V. Ajjarapu, G. Andersson, A. Bose, C. Canizares, N. Hatziargyriou, D. Hill, A. Stankovic, C. Taylor, T. Van Cutsem and V. Vittal, “Definition and Classification of Power System Stability IEEE/CI GRE Joint Task Force on Stability Terms and Definitions,” IEEE Transactions on Power Systems, Vol. 19, No. 3, 2004, pp. 1387-1401. doi:10.1109/TPWRS.2004.825981

[2] IEEE Std 1159-2009 (Revision of IEEE Std 1159-1995) Recommended Practice for Monitoring Electric Power Quality, IEEE Std., 2009.

[3] R. Tonkoski and L. A. C. Lopes, “Enhanced Part Load Operation of Hybrid Mini-Grids with High Penetration of Photovoltaics,” 3rd Brazilian Conference on Solar En ergy, Belém, 21-24 September 2010.

[4] K. Elamari and L. A. C. Lopes, “Frequency Based Con trol of Electric Water Heaters in Small PV-Diesel Hybrid Mini-Grids,” 25th Canadian Conference on Electrical and Computer Engineering, Montreal, 29 April-2 May 2012, pp. 1-4.

[5] L. A. C. Lopes and M. Dalal-Bachi, “Economic Dispatch and Demand Side Management via Frequency Control in PV-Diesel Hybrid Mini-Grids,” 6th European Conference on PV-Hybrid and Mini-Grids, Chambery, 26-27 April 2012, pp. 266-273.

[6] F. Katiraei, R. Iravani, N. Hatziargyriou and A. Dimeas, “Microgrids Management,” IEEE Power and Energy Magazine, Vol. 6, No. 3, 2008, pp. 54-65. doi:10.1109/MPE.2008.918702

[7] J. Morren, S. de Haan and J. Ferreira, “Contribution of DG Units to Primary Frequency Control,” 2005 International Conference on Future Power Systems, Amsterdam, 18 November 2005, p. 6.

[8] S. De Haan, R. Van Wesenbeeck and K. Visscher, “VSG Control Algorithms: Present Ideas,” 2008. http://www.vsync.eu. Project VSYNC

[9] K. Visscher and S. De Haan, “Virtual Synchronous Machines (VSGs) for Frequency Stabilisation in Future Grids with a Significant Share of Decentralized Generation,” CIRED Seminar SmartGrids for Distribution, Frankfurt, 23-24 June 2008, pp. 1-4.

[10] Q. C. Zhong and G. Weiss, “Static Synchronous Generators for Distributed Generation and Renewable Energy,” Power Systems Conference and Exposition, Seattle, 15-18 March 2009, pp. 1-6.

[11] M. Van Wesenbeeck, S. de Haan, P. Varela and K. Visscher, “Grid Tied Converter with Virtual Kinetic Storage,” PowerTech, 2009 IEEE Bucharest, Bucharest, 28 June-2 July 2009, pp. 1-7.

[12] Q. C. Zhong and G. Weiss, “Synchronverters: Inverters That Mimic Synchronous Generators,” IEEE Transactions on Industrial Electronics, Vol. 58, No. 4, 2011, pp. 1259-1267. doi:10.1109/TIE.2010.2048839

[13] J. Morren, S. de Haan, W. Kling and J. Ferreira, “Wind Turbines Emulating Inertia and Supporting Primary Frequency Control,” IEEE Transactions on Power Systems, Vol. 21, No. 1, 2006, pp. 433-434. doi:10.1109/TPWRS.2005.861956

[14] X. Yingcheng and T. Nengling, “Review of Contribution to Frequency Control through Variable Speed Wind Turbine,” Renewable Energy, Vol. 36, No. 6, 2011, pp. 1671 1677. http://www.sciencedirect.com/science/article/pii/S0960148110005112 =0pt

[15] M. Torres and L. A. C. Lopes, “Inverter-Based Virtual Diesel Generator for Laboratory-Scale Applications,” 36th Annual Conference on IEEE Industrial Electronics Society, Glendale, 7-10 November 2010, pp. 532-537.

[16] T. S. Lee, “Input-Output Linearization and Zero-Dynamics Control of Three-Phase ac/dc Voltage-Source Converters,” IEEE Transactions on Power Electronics, Vol. 18, No. 1, 2003, pp. 11-22. doi:10.1109/TPEL.2002.807145