A Simplified Approach to Calculate the Earth Fault Current Division Factor Passing Through the Substation Grounding System

Document Type : Article

Authors

1 University of Science and Technology of Mazandaran, P.O.Box: 48518-78195, Behshahr, Iran

2 University of Science and Technology of Mazandaran, P.O.Box 48518-78195, Behshahr, Iran

Abstract

The main aim of designing a safe grounding system is to provide a low impedance path to the flow of the earth fault currents without exceeding the operational constraints and equipment limits that will ensure electrical continuity. One of the most significant and well-known parameters to design a safe grounding system in power systems is the exact determination of the maximum earth fault current division factor. This paper presents a simplified and accurate method to calculate the earth fault current division factor in different states of the earth fault occurrence within and the vicinity of the substation under study. In the proposed method, a hybrid overhead-cable line, the impact of the frozen soil, mutual coupling between phase conductors and guard wires, grounding system resistance of adjacent substations, different tower footing resistances, the impact of the phase conductor impedance, and different spans in transmission lines can be considered. In addition, a closed-form formulation is also developed for the occurrence of the earth fault on the transmission line. Finally, details of the analysis results of this study have been compared with other methods in the literature. The validity and accuracy of the proposed approach also have been assayed and confirmed in details.

Keywords


 References:
[1] Ramezani, N., Shahrtash, S. M. “A complete procedure to determine earth fault current distribution and split factor for grounding grid design of HV substations”, Iranian Journal of Science & Technology, Transaction B, Engineering, 32(3), pp. 205-221 (2008).
[2] Popovic, L. M. “Practical method for evaluating ground fault current distribution in station, towers and ground wire”, IEEE Transactions On Power Delivery, 13(1), pp. 123-128 (1998).
[3] Popovic, L. M. “Practical method for evaluating ground fault current distribution in station supplied by an unhomogeneous line”, IEEE Trans. On Power Delivery, 12(2), pp. 722-727 (1997).
[4] Hans, R., Arora, J. K., Soni, S. K. “A practical approach for computation of grid current”, IEEE Transactions on Power Delivery, 14(3), pp. 897-902 (1999).
[5] Nahman, J. M. “Proximity effects on formed by a substation and the associated transmission lines”, IEE Proceedings, 135(6), pp. 497-502 (1988).
[6] Popovic, L. M. “Efficient reduction of fault current through the grounding grid of substation supplied by cable line”, IEEE Transactions on Power Delivery, 15(2), pp. 556-561 (2000).
[7] Popovic, L. M. “Ground fault current distribution when a ground fault occurs in HV substations located in an urban area”, Progress in Electromagnetics Research, B (59), pp. 167–179 (2014).
 [8] Verma, R., Mukhedkar, D. “Ground fault current distribution in sub-station, towers and ground wire”, IEEE Transactions on Power Apparatus and Systems, PAS-98(3), pp. 724-730 (1979).
 [9] Dawalibi, F. “Ground fault current distribution between soil and neutral conductors”, IEEE Transactions on Power Apparatus and Systems, PAS-99(2), pp. 452-461 (1980).
[10] Klucznik J. “Earth wires currents calculation by tableau analysis” Electric Power Systems Research, 151, pp. 329-337 (2017).
[11] Silvestre, M.L., Dusonchet L., Favuzza, S., et al. “On the interconnections of HV-MV stations to global grounding systems”, IEEE Transactions on Industry Applications, 55(2), pp. 1126-1134 (2018).  
[12] De Oliveira-De Jesus, P. M., Rojas Quintana, A. A. “Short-circuit current distribution analysis using a network model based on a 5×5 primitive matrix”, International Transactions on Electrical and Energy Systems, 29 (9), pp. 1-16 (2019).
[13] Nassereddine, M., Hellany A., Nagrial M., et al. “Advanced HV earthing system for smart substations”, IEEE, International Conference on Electrical Engineering Research & Practice (ICEERP), Sydney, NSW, Australia (2019).
[14] Meliopoulos, A. P., Webb R. P., Joy E. B., et al. “Computation of maximum earth current in substation switchyards”, IEEE Transactions on Power Apparatus and Systems, PAS-102(9), pp. 3131-39 (1983).
[15] Ramezani, N., Shahrtash, S. M. “Computation of the split factor of earth fault currents by considering the proximity effects” Iranian Journal of Science & Technology, Transaction B, Engineering, 34(B3), pp. 289-305 (2010).
[16] Zou, J., Lee, J., Li, J., et al. “Evaluating, ground fault current distribution on overhead transmission lines using an iterative nodal analysis”, COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering, 30(2), pp. 622-640 (2011).
[17] He, J., Wu, J., Zhang, B., et al. “Fault current-division factor of substation grounding grid in seasonal frozen soil”, IEEE Transactions on Power Delivery, 28(2), pp. 855-865 (2013).
[18] Vintan, M. “A comparative parametric analysis of the ground fault current distribution on overhead Transmission Lines”, Advances in Electrical and Computer Engineering, 16(1), pp. 107-114 (2016).
[19] IEEE guide for safety in AC substation grounding, IEEE Std. 80 (2013).
[20] Ibrahim Khater, M., Negm Abdallah, E., Hassan Abbasy, N. “New methods for designing a grounding system for future expansion of high voltage substations”, IEEE, Twentieth International Middle East Power Systems Conference (MEPCON), Cairo University, Egypt (2018). 
 [21] Luewattana, K. “Effects of overvoltage on mesh-distributed and edge-distributed rods in rectangular ground grid systems of high voltage substations”, IEEE, 15th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON), Chiang Rai, Thailand (2018).
[22] Das, J. C. “Understanding symmetrical components for power system modeling”, John wiley and sons (2017).
[23] Mangione, S. "A simple method for evaluating ground-fault current transfer at the transition station of a combined overhead-cable line”, IEEE Transaction On Power Delivery, 23(3), pp. 1413 – 1418 (2008).
[24] Colella, P., Pons, E., Piran, C., et al. “Validation and testing of an analytical formulation to compute the reduction factor in MV grids”, IEEE Transactions on Industry Applications, 59(4), pp. 3403-3411 (2020).
[25] Di Silvestre, M. L., Dusonchet, L., Favuzza, S.,  et al. “Interconnections criteria of grounding grids in global grounding systems”, IEEE/IAS 54th Industrial and Commercial Power Systems Technical Conference (I&CPS), Niagara Falls, ON (2018).
  [26] Fickert, L., Mallits, T., Resch, M. “Earth fault current distribution and proof method of global earthing systems” 19th International Scientific Conference on Electric Power Engineering (EPE), Brno, Czech Republic (2018).  
 [27] Gajdzica, J., Nowak, W., Szpyra W., et al. “Modelling and analysis of currents flowing in high voltage power substations during ground short-circuits”, IEEE, 14th Selected Issues of Electrical Engineering and Electronics (WZEE), Szczecin, Poland (2018).
[28] Coppo, M., Bignucolo, F., Turri, R., et al. “Analysis of frequency distribution of ground fault-current magnitude in transmission networks for electrical safety evaluation”, Electric Power Systems Research,173, pp. 100-111 (2019).
[29] Gatta, F. M., Geri A., Lauria S., et al. “An equivalent circuit for the evaluation of cross-country fault currents in medium voltage (MV) distribution networks”, Energies, 11 (8), https://doi.org/10.3390/en11081929 (2018).
[30] Cerretti, A., D’Orazio, L., Gatta, F.M., et al. “Limitation of cross country fault currents in MV distribution networks by current limiting reactors connected between cable screens and primary substation earth electrode”, Electric Power Systems Research,205, 107720 (2022).