Comparison study among the different existing loss of excitation protection schemes in synchronous generator


  • Hamid Bentarzi University of Boumerdes
  • Ayache Mati Laboratory Signals and Systems (LSS), IGEE, University M’hamed Bougara Boumerdes
  • Jean-Claude MAUN Beams, ULB, Brusselles



Loss Of Excitation (LOE), positive-offset mho element, negative-offset mho element, loading conditions


Synchronous generator is the most important element of a power system and its fast and reliable protection is crucial. One of the most abnormal conditions in a generator is loss of excitation (LOE) which is harmful to both the generator and the power system. This condition should be detected and the generator isolated from the system to avoid generator damage as well as power system instability.

This work presents an experimental study and comparison of the two conventional LOE protection schemes, negative-offset and positive-offset mho element under different conditions. The results show that the two schemes can detect LOE fault under total or partial LOE conditions, however in terms of speed (fault detection time) the positive offset scheme is faster than the negative offset scheme under all loading conditions. Besides, the two LOE protection schemes are reliable and do not operate under power swing disturbances caused by any type of external faults.


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Author Biography

Hamid Bentarzi, University of Boumerdes

I have been faculty member in the Institute (IGEE), University M’hamed Bougara, Boumerdes, Algeria, since 1998.  I received Bachelor and M. Phil degrees from INELEC, Boumerdes, in 1989 and 1992 respectively, in applied Electronics. However, I defended PhD degree at the ENP, Algiers, on 2004. From 1993 to 1998 I had been lecturer at INELEC. Now, I am full professor and research team leader in Laboratory signals and systems (LSS). My research activities are centered upon control and protection systems reliability enhancement using the recent technologies. I have been author and co-author in more than hundred papers.




How to Cite

Bentarzi, H., Mati, A. and MAUN, J.-C. 2021. Comparison study among the different existing loss of excitation protection schemes in synchronous generator . Algerian Journal of Signals and Systems . 6, 4 (Dec. 2021), 206-213. DOI: