Document Type : Research Article


1 Department of Electrical Engineering, Khorramabad Branch, Islamic Azad University, Khorramabad, Lorestan, Iran.

2 Department of Electrical Engineering, Lorestan University, Khorramabad, Lorestan, Iran.


In this study, a novel stochastic planning method is proposed for AC-DC hybrid distribution networks. The proposed approach is based on the graph theory, and the optimal AC-DC structure of the network is selected among the system spanning trees. The presented method is a Mixed Integer Nonlinear Programming (MINLP) problem, which is solved using genetic algorithm. The buses and lines of the network can be either AC or DC to minimize the system investment costs in the master optimization problem. The location and capacity of the Distributed Energy Resources (DERs) as well as the site and size of the Electric Vehicle (EV) charging stations are optimized in the slave problem to minimize the network losses and system costs. The proposed model utilizes Monte Carlo simulation to deal with the stochastic variations of the renewable energy resources power and load demands. Besides, the converter efficiency curve in the proposed planning problem is modeled based on a function of its input current using PLECS software. The proposed approach for network design can be applied to different DG resources and AC-DC loads. The comparison between the simulation results of the proposed approach and the conventional AC planning method demonstrates the efficiency of the proposed model in reducing network losses and system costs.


Main Subjects

  1. Eajal, A.A., Shaaban, M.F., Ponnambalam, K. and El-Saadany, E.F., "Stochastic centralized dispatch scheme for AC/DC hybrid smart distribution systems", IEEE Transactions on Sustainable Energy, Vol. 7, No. 3, (2016), 1046-1059. (
  2. Peyghami, S., Mokhtari, H. and Blaabjerg, F., "Autonomous operation of a hybrid AC/DC microgrid with multiple interlinking converters", IEEE Transactions on Smart Grid, Vol. 9, No. 6, (2018), 6480-6488. (
  3. Wang, T., Li, C., Mi, D., Wang, Z. and Xiang, Y., "Coordinated modulation strategy considering multi-HVDC emergency for enhancing transient stability of hybrid AC/DC power systems", CSEE Journal of Power and Energy Systems, Vol. 6, No. 4, (2020), 806-815. (
  4. ElNozahy, M.S. and Salama, M.M.A., "Uncertainty-based design of a bilayer distribution system for improved integration of PHEVs and PV arrays", IEEE Transactions on Sustainable Energy, Vol. 6, No. 3, (2015), 659-674. (
  5. Kurohane, K., Senjyu, T., Yona, A., Urasaki, N., Goya, T. and Funabashi, T., "A hybrid smart AC/DC power system", IEEE Transactions on Smart Grid, Vol. 1, No. 2, (2010), 199-204. (
  6. Lotfjou, A., Fu, Y. and Shahidehpour, M., "Hybrid AC/DC transmission expansion planning," IEEE Transactions on Power Delivery, Vol. 27, No. 3, (2012), 1620-1628. (
  7. Doagou-Mojarrad, H., Rastegar, H. and Gharehpetian, G.B., "Probabilistic multi-objective HVDC/AC transmission expansion planning considering distant wind/solar farms", IET Science, Measurement & Technology, Vol. 10, No. 2, (2016), 140-149. (
  8. Meng, K., Zhang, W., Qiu, J., Zheng, Y. and Dong, Z.Y., "Offshore transmission network planning for wind integration considering AC and DC transmission options", IEEE Transactions on Power Systems, Vol. 34, No. 6, (2019), 4258-4268. (
  9. Torbaghan, S.S., Gibescu, M., Rawn, B.G. and Meijden, M., "A market-based transmission planning for HVDC grid-Case study of the North Sea", IEEE Transactions on Power Systems, Vol. 30, No. 2, (2015), 784-794. (
  10. Moradi-Sepahvand, M. and Amraee, T., "Hybrid AC/DC transmission expansion planning considering HVAC to HVDC conversion under renewable penetration", IEEE Transactions on Power Systems, Vol. 36, No. 1, (2021), 579-591. (
  11. Huang, L., Chen, Z., Cui, Q., Zhang, J., Wang, H. and Shu, J., "Optimal planning of renewable energy source and energy storage in a medium- and low-voltage distributed AC/DC system in China", The Journal of Engineering, Vol. 2019, No. 16, (2019), 2354-2361. (
  12. Wu, Z., Liu, P., Gu, W., Huang, H. and Han, J., "A bi-level planning approach for hybrid AC-DC distribution system considering N-1 security criterion", Applied Energy, Vol. 230, (2018), 417-428. (
  13. Wu, Z., Sun, Q., Gu, W., Chen, Y., Xu, H. and Zhang, J., "AC/DC hybrid distribution system expansion planning under long-term uncertainty considering flexible investment", IEEE Access, Vol. 8, (2020), 94956-94967. (
  14. Frank, S.M. and Rebennack, S., "Optimal design of mixed AC–DC distribution systems for commercial buildings: a nonconvex generalized benders decomposition approach", European Journal of Operational Research, Vol. 242, No. 3, (2015), 710-729. (
  15. Bagheri, A., Monsef, H. and Lesani, H., "Integrated distribution network expansion planning incorporating distributed generation considering uncertainties, reliability, and operational conditions", International Journal of Electrical Power & Energy Systems, Vol. 73, (2015), 56-70. (
  16. Lotfi, H. and Khodaei, A., "AC versus DC microgrid planning", IEEE Transactions on Smart Grid, Vol. 8, No. 1, (2017), 296-304. (
  17. Hamad, A.A., Nassar, M.E., El-Saadany, E.F. and Salama, M.M.A., "Optimal configuration of isolated hybrid AC/DC microgrids", IEEE Transactions Smart Grid, Vol. 10, No. 3, (2019), 2789-2798. (
  18. Ghadiri, A., Haghifam, M.R. and Larimi, S.M.M., "Comprehensive approach for hybrid AC/DC distribution network planning using genetic algorithm", IET Generation, Transmission & Distribution, Vol. 11, No. 16, (2017), 3892-3902. (
  19. Ahmed, H.M.A., Eltantawy, A.B. and Salama, M.A., "A planning approach for the network configuration of AC-DC hybrid distribution systems", IEEE Transactions on Smart Grid, Vol. 9, No. 3, (2018), 2203-2213. (
  20. Ahmed, H.M.A., Eltantawy, A.B. and Salama, M.M.A., "A reliability-based stochastic planning framework for AC-DC hybrid smart distribution systems", International Journal of Electrical Power & Energy Systems, Vol. 107, (2019), 10-18. (
  21. Blaabjerg, F., Jaeger, U. and Munk-Nielsen, S., "Power losses in PWM-VSI inverter using NPT or PT IGBT devices", IEEE Transactions on Power Electronics, Vol. 10, No. 3, (1995), 358-367. (
  22. Islam, M.M., Rahman, M.A. and Islam, M.R., "Power loss and thermalimpedance modeling of multilevel power converter with discontinuous modulation", IEEE Transactions on Energy Conversion, Vol. 36, No. 1, (2020), 36-47. (
  23. Ebrahimi, J., Abedini, M., Rezaei M.M. and Nasri M., "Optimum design of a multi-form energy in the presence of electric vehicle charging station and renewable resources considering uncertainty", Sustainable Energy, Grids and Networks, Vol. 23, (2020), 100375. (
  24. Sabzian Molaee, Z., Rokrok, E. and Doostizadeh M., "A unified power flow approach using VSC-efficiency for AC-DC distribution systems operating at grid connected and islanded modes", International Journal of Electrical Power & Energy Systems, Vol. 130, (2021), 106906. (