Detailed modelling and analysis of digital mho distance relay with single-pole operation




electrical engineering, power system protection, PSCAD/EMTDC, time-domain analysis


This paper introduces a methodology for modelling a digital admittance-type distance relay using PSCAD/EMTDC. The proposed distance relay was tested in a simulation of the Brazilian power grid with predetermined fault scenarios. The goal of this paper is to make a detailed evaluation of the mho distance relay. The main aspects include the correct operation of the distance relay, fault resistance effects on the mho characteristics, and the fault detection time of this relay. A new approach to analyse the fault detection time is presented, considering several simulated fault scenarios. The results demonstrate that the fault resistance influences the fault detection time and severely affects the distance relay’s general performance. The fault detection time is not constant. It varies within a time interval, considering different fault types, fault locations, and fault resistances. The confidence interval calculation provides a detailed range of the fault detection time, considering its upper and lower limits.


S. H. Horowitz, A. G. Phadke. Power System Relaying, chap. Nonpilot Distance Protection of Transmission Lines, pp. 101–131. 3rd ed. John Wiley & Sons, Ltd., 2008.

C. A. B. Da Costa, N. S. D. Brito, B. A. De Souza. A methodology for distance relay modeling. IEEE Latin America Transactions 16(5):1388–1394, 2018.

R. H. Salim, D. P. Marzec, A. S. Bretas. Phase distance relaying with fault resistance compensation for unbalanced systems. IEEE Transactions on Power Delivery 26(2):1282–1283, 2011.

J. Choi, Y. Han, I. Suh, et al. A study on the effects of new facts installations on existing distance protection relays. IFAC Proceedings Volumes 36(20):279–283, 2003.

S. M. Hashemi, M. Sanaye-Pasand. Distance protection during asymmetrical power swings: Challenges and solutions. IEEE Transactions on Power Delivery 33(6):2736–2745, 2018.

A. Manori, M. Tripathy. Protection of TCSC transmission line by wavelet based advance Mho relay. In 2018 5th IEEE Uttar Pradesh Section International Conference on Electrical, Electronics and Computer Engineering (UPCON), pp. 1–4. 2018.

P. R. Khade, M. P. Thakre. Optimal reach settings of Mho relay for series compensated transmission line protection. In 2020 4th International Conference on Electronics, Communication and Aerospace Technology (ICECA), p. 307–313. 2020.

Y. Liang, W. Li, W. Zha. Adaptive mho characteristic-based distance protection for lines emanating from photovoltaic power plants under unbalanced faults. IEEE Systems Journal pp. 1–11, 2020.

C. R. Mason. The art and science of protective relaying. Wiley, New York, 1956.

H. Beleed, B. K. Johnson, H. L. Hess. An examination of the impact of D-FACTS on the dynamic behavior of mho and quadrilateral ground distance elements. In 2020 IEEE Power & Energy Society Innovative Smart Grid Technologies Conference (ISGT), pp. 1–5. 2020.

L. Gérin-Lajoie. A MHO distance relay device in EMTPWorks. Electric Power Systems Research 79(3):484–491, 2009.

K. Pipaliya, V. Makwana. Modeling and simulation of digital distance protection scheme for quadrilateral characteristics using PSCAD. International Journal of Advance Engineering and Research Development 2(5):1238–1246, 2015.

S. R. Samantaray, P. K. Dash. Transmission line distance relaying using a variable window short-time Fourier transform. Electric Power Systems Research 78(4):595–604, 2008.

Manitoba HVDC Research Centre. Applications of PSCADTM/EMTDCTM. Winnipeg, 2008.

Institute of Electrical and Electronic Engineers. Guide for protective relay applications to transmission lines. In IEEE Std C37.113-2015 (Revision of IEEE Std C37.113-1999), pp. 1–141. 2016.

A. M. Abdullah, K. Butler-Purry. Distance protection zone 3 misoperation during system wide cascading events: The problem and a survey of solutions. Electric Power Systems Research 154:151–159, 2018.

S. G. Aquiles Perez, M. S. Sachdev, T. S. Sidhu. Modeling relays for use in power system protection studies. In Canadian Conference on Electrical and Computer Engineering, 2005, pp. 566–569. 2005.

A. V. Oppenheim, R. W. Schafer. Discrete-Time Signal Processing, chap. Digital Processing of Analog Signals, pp. 153–237. 3rd ed. Pearson, 2010.

A. M. Goler. PSCAD On-Line Help System, chap. PFFT 49 Low Pass, Anti-Aliasing Filter. PSCAD, Winnipeg, 1993.

W. Kester. MT-002 TUTORIAL what the nyquist criterion means to your sampled data system design. Analog Devices pp. 1–12, 2009.

R. Jayasinghe, S. Woodford. PSCAD On-Line Help System, chap. Online Fast Fourier Transform. PSCAD, Winnipeg, 1992.

M. Inci, M. Buyuk, M. Tumay. FFT based reference signal generation to compensate simultaneous voltage sag/swell and voltage harmonics. In 2016 IEEE 16th International Conference on Environment and Electrical Engineering (EEEIC), pp. 3–7. 2016.

K. R. Rao, D. N. Kim, J.-J. Hwang. Fast Fourier Transform - Algorithms and Applications. Springer Netherlands, Dordrecht, 2010.

A. G. Phadke, J. S. Thorp. Computer Relaying for Power Systems, chap. Relaying Practices. Wiley, Chichester, UK, 2009.

D. D. Fentie. Understanding the dynamic mho distance characteristic. In 2016 69th Annual Conference for Protective Relay Engineers (CPRE), pp. 1–15. 2016.

M. da C. Siqueira. Desempenho da proteção de distância sob diferentes formas de polarização, 2007. Federal University of Rio de Janeiro.

B. Gustavsen, G. Irwin, R. Mangelrød, et al. International Converence on Power System Transients (IPST), chap. Transmission line models for the simulation of interaction phenomena between parallel AC and DC overhead lines, pp. 61–67. 1999.

A. Morched, B. Gustavsen, M. Tartibi. A universal model for accurate calculation of electromagnetic transients on overhead lines and underground cables. IEEE Transactions on Power Delivery 14(3):1032–1038, 1999.

F. M. Dekking, C. Kraaikamp, H. P. Lopuhaa, L. E. Meester. A Modern Introduction to Probability and Statistics, Understanding Why and How. Springer, London, 2005.