Owing to the increasing penetration of single-phase small generation units and electric vehicles connected to distribution grids, system operators are facing challenges related to local unbalanced voltage rise or drop issues, which may lead to a violation of the allowed voltage band. To address this problem, distribution transformers with on-load tapping capability are under development. This study presents model and experimental validation of a 35 kVA three-phase power distribution transformer with independent on-load tap-changer control capability on each phase. With the purpose of investigating and evaluating its effectiveness under different operative conditions, appropriate scenarios are defined and tested considering both balanced and unbalanced situations, also in case of reverse power flow. The experimental setup is built starting from an analysis of a Danish distribution network, in order to reproduce the main feature of an unbalanced grid. The experimental activities are recreated in by carrying out dynamics simulation studies, aiming at validating the implemented models of both the transformer as well as the other grid components. Phase–neutral voltages’ deviations are limited, proving the effectiveness of the phase-independent tap operations. Furthermore, minor deviations of the results from simulations and experiments confirm that all the system components have been properly modelled.

References

1. 1)
  - 21. ‘Automatic Voltage Stabilizer – Datasheet’. Schuntermann Transformatoren Gmbh. Available http://www.renecost.de/wp-content/uploads/2015/02/Spannungskonstanthalter_290414.pdf.
2. 2)
  - 36. El Moursi, M.S., Zeineldin, H.H., Kirtley, J.L., Alobeidli, K.: ‘A dynamic master/slave reactive power-management scheme for smart grids with distributed generation’, IEEE Trans. Power Deliv., 2014, 29, (3), pp. 1157–1167 (doi: 10.1109/TPWRD.2013.2294793).
3. 3)
  - 3. Caldon, R., Coppo, M., Turri, R.: ‘Distributed voltage control strategy for LV networks with inverter-interfaced generators’, Electr. Power Syst. Res., 2014, 107, pp. 85–92 (doi: 10.1016/j.epsr.2013.09.009).
4. 4)
  - 17. Braun, M., Stetz, T., Bründlinger, R., et al: ‘Is the distribution grid ready to accept large-scale photovoltaic deployment? State of the art, progress, and future prospects’, Prog. Photovoltaics, 2012, 20, (6), pp. 681–697 (doi: 10.1002/pip.1204).
5. 5)
  - 1. Stetz, T., Kraiczy, M., Braun, M., et al: ‘Technical and economical assessment of voltage control strategies in distribution grids’, Prog. Photovolt. Res. Appl., 2013, 21, (6), pp. 1292–1307 (doi: 10.1002/pip.2331).
6. 6)
  - 12. Einfalt, A., Kupzog, F., Brunner, H., et al: ‘Control strategies for smart low voltage grids – the project DG DemoNet – smart LV grid’. Integration of Renewables into the Distribution Grid, CIRED 2012 Workshop, Lisbon, Portugal, 2012, no. 0238, pp. 1–4.
7. 7)
  - 4. Knezović, K., Marinelli, M., Møller, R.J., et al: ‘Analysis of voltage support by electric vehicles and photovoltaic in a real Danish low voltage network’. Proc. 49th Int. Universities Power Engineering Conf. (UPEC), Cluj-Napoca, Romania, 2014.
8. 8)
  - 9. Kechroud, A., Ribeiro, P.F., Kling, W.L.: ‘Distributed generation support for voltage regulation: an adaptive approach’, Electr. Power Syst. Res., 2014, 107, pp. 213–220 (doi: 10.1016/j.epsr.2013.09.004).
9. 9)
  - 11. Kumar, C., Mishra, M.K.: ‘A voltage-controlled DSTATCOM for power-quality improvement’, IEEE Trans. Power Deliv., 2014, 29, (3), pp. 1499–1507 (doi: 10.1109/TPWRD.2014.2310234).
10. 10)
  - 23. ELSPEC: ‘G4500 & G3500 portable power quality analyzer USER & INSTALLATION MANUAL’. V1.2 SMX-0618-0100, 2013.
11. 11)
  - 26. Pillay, P., Manyage, M.: ‘Definitions of voltage unbalance’, IEEE Power Eng. Rev., 2002, 22, (11), pp. 49–50.
12. 12)
  - 25. Martinenas, S., Marinelli, M., Andersen, P.B., et al: ‘Implementation and demonstration of grid frequency support by V2G enabled electric vehicle’. Proc. 49th Int. Universities Power Engineering Conf. (UPEC), Cluj-Napoca, Romania, 2014, pp. 1–6.
13. 13)
  - 11. IEEE Task Force on Load Representation for Dynamic Performance: ‘Load representation for dynamic performance analysis’, IEEE Trans. Power. Syst., 1993, 8, (2), pp. 472–482 (doi: 10.1109/59.260837).
14. 14)
  - 15. ‘GRIDCON® TRANSFORMER – Datasheet’. Maschinenfabrik Reinhausen Gmbh. Available at – http://www.reinhausen.com/en/desktopdefault.aspx/tabid-1605/1835_read-4652/.
15. 15)
  - 18. Meersman, B., Renders, B., Degroote, L., et al: ‘Three-phase inverter-connected DG-units and voltage unbalance’, Electr. Power Syst. Res., 2011, 81, (4), pp. 899–906 (doi: 10.1016/j.epsr.2010.11.024).
16. 16)
  - 20. Zecchino, A., Marinelli, M., Hu, J., et al: ‘Voltage control for unbalanced low voltage grids using a decoupled-phase on-load tap-changer transformer and photovoltaic inverters’. 50th Int. Universities Power Engineering Conf., Stoke-On-Trent, UK, 2015, pp. 1–6.
17. 17)
  - 8. Golsorkhi, M.S., Lu, D.: ‘A control method for inverter-based islanded microgrids based on V–I droop characteristics’, IEEE Trans. Power Deliv., 2014, 30, (3), pp. 1196–1204 (doi: 10.1109/TPWRD.2014.2357471).
18. 18)
  - 16. ‘FITformer® REG – Datasheet’. Siemens. Available at http://www.energy.siemens.com/hq/en/power-transmission/transformers/distribution-transformers/distribution/fit-former-reg.htm.
19. 19)
  - 19. Hu, J., Marinelli, M., Coppo, M., et al: ‘Coordinated voltage control of a decoupled three-phase on-load tap changer transformer and photovoltaic inverters for managing unbalanced networks’, Electr. Power Syst. Res., 2016, 131, pp. 264–274 (doi: 10.1016/j.epsr.2015.10.025).
20. 20)
  - 13. Leisse, I., Samuelsson, O., Svensson, J.: ‘Coordinated voltage control in medium and low voltage distribution networks with wind power and photovoltaics’. IEEE PowerTech Conf., Grenoble, France, 2013, pp. 1–6.
21. 21)
  - 4. Sinsukthavorn, W., Ortjohann, E., Mohd, A., et al: ‘Control strategy for three-/four-wire-inverter-based distributed generation’, IEEE Trans. Ind. Electron., 2012, 59, pp. 3890–3899 (doi: 10.1109/TIE.2012.2188871).
22. 22)
  - 10. Carradore, L., Turri, R.: ‘Electric vehicles participation in distribution network voltage regulation’. 2010 45th Int. University Power Engineering Conf. (UPEC), Cardiff, UK, 2010, pp. 1–6.
23. 23)
  - 5. Schneider, K.P., Fuller, J.C., Tuffner, F.K., et al: ‘Evaluation of conservation voltage reduction (CVR) on a national level’ (Pacific Northwest National Laboratory, Richland, WA, USA, 2010), July 2010, p. 114.
24. 24)
  - 7. Uluski, R.: ‘VVC in the smart grid era’. IEEE PES General Meeting, Minneapolis, MN, 2010, pp. 1–7.
25. 25)
  - 6. Rahimi, S., Marinelli, M., Silvestro, F.: ‘Evaluation of requirements for volt/var control and optimization function in distribution management systems’. IEEE Int. Energy Conf. Exhibition Energycon, Florence, Italy, 2012, pp. 331–336.
26. 26)
  - 22. ‘SYSLAB-PowerLabDK’. Available at http://www.powerlab.dk/facilities/syslab.aspx.

Experimental testing and model validation of a decoupled-phase on-load tap-changer transformer in an active network

References

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