Secondary voltage regulation based on average voltage control
This paper compares a conventional Secondary Voltage Regulation (SVR) scheme based on pilot nodes with a proposed SVR that takes into account average voltages of control zones. Voltage control significance for the operation of power systems has promoted several strategies in order to deal with this problem. However, the Hierarchical Voltage Control System (HVCS) is the only scheme effectively implemented with some relevant applications into real power systems.
The HVCS divides the voltage control problem into three recognized stages. Among them, the SVR is responsible for managing reactive power resources to improve network voltage profile. Conventional SVR is based on dividing the system into some electrically distant zones and controlling the voltage levels of some specific nodes in the system named pilot nodes, whose voltage levels are accepted as appropriate indicators of network voltage profile.
The SVR approach proposed in this work does not only consider the voltage on pilot nodes, but it also takes the average voltages of the defined zones to carry out their respective control actions. Additionally, this innovative approach allows to integrate more reactive power resources into each zone according to some previously defined participation factors.
The comparison between these strategies shows that the proposed SVR achieves a better allocation of reactive power in the system than conventional SVR, and it is able to keep the desired voltage profile, which has been expressed in terms of network average voltage.
 V. Alimisis and P. C. Taylor, “Zoning Evaluation for Improved Coordinated Automatic Voltage Control,” IEEE Trans. Power Syst., vol. 30, no. 5, pp. 2736–2746, Sep. 2015.
 A. Morattab, O. Akhrif, and M. Saad, “Decentralised coordinated secondary voltage control of multi-area power grids using model predictive control,” IET Gener. Transm. Distrib., vol. 11, no. 18, pp. 4546–4555, Dec. 2017.
 Q.-Y. Liu, C.-C. Liu, and Q.-F. Liu, “Coordinated Voltage Control With Online Energy Margin Constraints,” IEEE Trans. Power Syst., vol. 31, no. 3, pp. 2064–2075, May 2016.
 A. Morattab, A. Dalal, O. Akhrif, M. Saad, and S. Lefebvre, “Model Predictive Coordinated secondary voltage control of power grids,” in 2012 International Conference on Renewable Energies for Developing Countries (REDEC), 2012, pp. 1–6.
 H. Lefebvre, D. Fragnier, J. Y. Boussion, P. Mallet, and M. Bulot, “Secondary coordinated voltage control system: feedback of EDF,” in 2000 Power Engineering Society Summer Meeting (Cat. No.00CH37134), 2000, vol. 1, pp. 290–295.
 J. Rios, A. Zamora, M. R. A. Paternina, A. Lopez, and E. Vazquez, “Secondary voltage control areas through energy levels,” in 2016 IEEE PES Transmission & Distribution Conference and Exposition-Latin America (PES T&D-LA), 2016, pp. 1–6.
 H. Vu, P. Pruvot, C. Launay, and Y. Harmand, “An improved voltage control on large-scale power system,” IEEE Trans. Power Syst., vol. 11, no. 3, pp. 1295–1303, 1996.
 G. Grigoras, B.-C. Neagu, F. Scarlatache, and R. C. Ciobanu, “Identification of pilot nodes for secondary voltage control using K- means clustering algorithm,” in 2017 IEEE 26th International Symposium on Industrial Electronics (ISIE), 2017, pp. 106–110.
 International Council on Large Electric Systems-CIGRE, “Coordinated voltage control in transmission networks,” 2007.
 N. A. Daher, I. Mougharbel, M. Saad, and H. Y. Kanaan, “Comparative study of partitioning methods used for secondary voltage control in distributed power networks,” in 2013 IEEE International Conference on Smart Energy Grid Engineering (SEGE), 2013, pp. 1–7.
 Bo Hu, C. A. Canizares, and M. Liu, “Secondary and Tertiary Voltage Regulation based on optimal power flows,” in 2010 IREP Symposium Bulk Power System Dynamics and Control - VIII (IREP), 2010, pp. 1–6.
 N. Martins, J. C. R. Ferraz, S. Gomes, P. E. M. Quintao, and J. A. Passos, “A demonstration example of secondary voltage regulation: dynamic simulation and continuation power flow results,” in 2001 Power Engineering Society Summer Meeting. Conference Proceedings (Cat. No.01CH37262), 2001, pp. 791–796.
 P. Lagonotte, J. C. Sabonnadiere, J.-Y. Leost, and J.-P. Paul, “Structural analysis of the electrical system: application to secondary voltage control in France,” IEEE Trans. Power Syst., vol. 4, no. 2, pp. 479–486, May 1989.
 F. Milano, Power system modelling and scripting, Illustrate. London: Springer Science & Business Media, 2010.
 M. K. Verma and S. C. Srivastava, “Approach to determine voltage control areas considering impact of contingencies,” IEE Proc. - Gener. Transm. Distrib., vol. 152, no. 3, pp. 342–350, 2005.