A control strategy is formulated for photovoltaic generators (PVG) operating in parallel in a Microgrid. A radial microgrid is considered and when it is isolated from the utility grid, the PVG's must operate in the voltage-frequency control mode in the absence of a storage or a diesel generator unit. It is observed that the conventional P-f and Q-v droop control method fails to deliver correct power references for inverters operating in parallel when network impedance is unequal, and therefore an active power-reactive power-frequency-derivative (PQFD) droop control is proposed to achieve an error free power sharing. Seamless operation from the grid connected mode to isolated mode and vice-versa is achieved with the help of the aforementioned control, which in addition assists in the alleviation of sluggish response in the presence of Induction motor (IM) loads by providing appropriate damping. For a transient free transfer from isolated mode to grid connected mode, a synchronisation control is formulated which helps in the proper reconnection. The controller designed is tested in both Microgrid and the grid connected mode and during transition. The controller gains used in the paper have been obtained with the help of a small signal analysis of the system considered.

References

1. 1)
  - 17. Delfino, F., Procopio, R., Rossi, M., Ronda, G.: ‘Integration of large-size photovoltaic systems into the distribution grids: a p–q chart approach to assess reactive support capability’, IET Renew. Power Gener., 2010, 4, (4), pp. 329–340 (doi: 10.1049/iet-rpg.2009.0134).
2. 2)
  - 3. Majumder, R., Chaudhuri, B., Ghosh, A., et al: ‘Improvement of stability and load sharing in an autonomous microgrid using supplementary droop control loop’, IEEE Trans. Power Syst., 2010, 25, (2), pp. 796–808 (doi: 10.1109/TPWRS.2009.2032049).
3. 3)
  - 17. Wang, J., Chang, N.C.P., Feng, X., et al: ‘Design of a generalized control algorithm for parallel inverters for smooth microgrid transition operation’, IEEE Trans. Ind. Electron., 2015, 62, (8), pp. 4900–4914 (doi: 10.1109/TIE.2015.2404317).
4. 4)
  - 19. Du, W., Jiang, Q., Erickson, M.J., et al: ‘Voltage-source control of PV inverter in a CERTS microgrid’, IEEE Trans. Power Deliv., 2014, 29, (4), pp. 1726–1734 (doi: 10.1109/TPWRD.2014.2302313).
5. 5)
  - 1. Patrick, A.M.B., Harish, S.P., Urpelainen, J.: ‘Quantifying slum electrification in India and explaining local variation’, Energy, 2015, 80, (1), pp. 203–212.
6. 6)
  - 9. Kahrobaeian, A., Ibrahim, Y.: ‘Mitigation of low-frequency oscillations in autonomous converter-based micro-grids with induction motor load’, IEEE Trans. Ind. Electron., 2014, 99, pp. 1–10.
7. 7)
  - 8. Vandoorn, T.L., Meersman, B., De Kooning, J.D.M., et al: ‘Transition from islanded to grid-connected mode of microgrids with voltage-based droop control’, IEEE Trans. Power Syst., 2013, 28, (3), pp. 2545–2553 (doi: 10.1109/TPWRS.2012.2226481).
8. 8)
  - 17. Balathandayuthapani, S., Edrington, C.S., Henry, S.D., et al: ‘Analysis and control of a photovoltaic system: application to a high-penetration case study’, IEEE Syst. J., 2012, 6, (2), pp. 213–219 (doi: 10.1109/JSYST.2011.2162889).
9. 9)
  - 20. Elrayyah, A., Sozer, Y., Elbuluk, M.E.: ‘Modeling and control design of microgrid-connected PV-based sources’, IEEE J. Emerging Sel. Top. Power Electron., 2014, 2, (4), pp. 907–919 (doi: 10.1109/JESTPE.2014.2330797).
10. 10)
  - 6. Mohamed, Y.A.R.I., El-Saadany, E.: ‘Adaptive decentralized droop controller to preserve power sharing stability of paralleled inverters in distributed generation microgrids’, IEEE Trans. Power Electron., 2008, 23, (6), pp. 2806–2816 (doi: 10.1109/TPEL.2008.2005100).
11. 11)
  - 10. De Brabandere, K., Bolsens, B., Van den Keybus, J., et al: ‘A voltage and frequency droop control method for parallel inverters’, IEEE Trans. Power Electron., 2007, 22, (4), pp. 1107–1115 (doi: 10.1109/TPEL.2007.900456).
12. 12)
  - 5. Liu, Y., Bebic, J., Kroposki, B., et al: ‘Distribution system voltage performance analysis for high-penetration PV’. Proc. of IEEE Energy 2030 Conf., November 2008, pp. 1–8.
13. 13)
  - 12. Kim, J., Guerrero, J.M., Rodriguez, P., et al: ‘Mode adaptive droop control with virtual output impedances for an inverter-based flexible AC microgrid’, IEEE Trans. Power Electron., 2011, 26, (3), pp. 689–701 (doi: 10.1109/TPEL.2010.2091685).
14. 14)
  - 36. Pogaku, N., Prodanovic, M., Green, T.C.: ‘Modelling, analysis and testing of autonomous operation of an inverter based microgrid’, IEEE Trans. Power Electron., 2007, 22, (2), pp. 613–625 (doi: 10.1109/TPEL.2006.890003).
15. 15)
  - 3. Adhikari, S., Li, F., Li, H.: ‘P–Q and P–V control of photovoltaic generators in distribution systems’, IEEE Trans. Smart Grid, 2015, 6, (6), pp. 2929–2941 (doi: 10.1109/TSG.2015.2429597).
16. 16)
  - 1. Vasquez, J.C., Guerrero, J.M., Savaghebi, M., Eloy-Garcia, J., Teodorescu, R.: ‘Modeling, analysis, and design of stationary-reference-frame droop-controlled parallel three-phase voltage source inverters’, IEEE Trans. Ind. Electron., 2013, 60, (4), pp. 1271–1280 (doi: 10.1109/TIE.2012.2194951).
17. 17)
  - 15. Chandorkar, M., Divan, D., Adapa, R.: ‘Control of parallel connected inverters in standalone AC supply systems’, IEEE Trans. Ind. Appl., 1993, 29, (1), pp. 136–143 (doi: 10.1109/28.195899).
18. 18)
  - 92. Blaabjerg, F., Teodorescu, R., Liserre, M., Timbus, A.V.: ‘Overview of control and grid synchronization for distributed power generation systems’, IEEE Trans. Ind. Electron., 2006, 53, (5), pp. 1398–1409 (doi: 10.1109/TIE.2006.881997).
19. 19)
  - 10. Zamani, M.A., Yazdani, A., Sidhu, T.S.: ‘A control strategy for enhanced operation of inverter-based microgrids under transient disturbances and network faults’, IEEE Trans. Power Deliv., 2012, 27, (4), pp. 1737–1747 (doi: 10.1109/TPWRD.2012.2205713).
20. 20)
  - 63. Guerrero, J.M., Vasquez, J.C., Matas, J., de Vicuna, L.G., Castilla, M.: ‘Hierarchical control of droop-controlled AC and DC microgrids – a general approach toward standardization’, IEEE Trans. Ind. Electron., 2011, 58, (1), pp. 158–172 (doi: 10.1109/TIE.2010.2066534).
21. 21)
  - 14. Kim, Y-Su., Eung-Sang, K., Seung-II, M.: ‘Frequency and voltage control strategy of standalone microgrids with high penetration of intermittent renewable generation systems’, IEEE Trans. Power Syst., 2016, 31, (1), pp. 718–728 (doi: 10.1109/TPWRS.2015.2407392).

Efficient power sharing approach for photovoltaic generation based microgrids

References

Related content