Probability-based approach for parametrisation of traditional underfrequency load-shedding schemes

Probability-based approach for parametrisation of traditional underfrequency load-shedding schemes

For access to this article, please select a purchase option:

Buy article PDF
(plus tax if applicable)
Buy Knowledge Pack
10 articles for $120.00
(plus taxes if applicable)

IET members benefit from discounts to all IET publications and free access to E&T Magazine. If you are an IET member, log in to your account and the discounts will automatically be applied.

Learn more about IET membership 

Recommend Title Publication to library

You must fill out fields marked with: *

Librarian details
Your details
Why are you recommending this title?
Select reason:
IET Generation, Transmission & Distribution — Recommend this title to your library

Thank you

Your recommendation has been sent to your librarian.

Underfrequency load shedding (UFLS) is one of the measures performed when an emergency situation occurs in the power system in order to prevent system collapse. Owing to its importance, a lot of effort is dedicated to research and development of the optimal UFLS. Therefore, several different approaches are available to improve the so-called traditional UFLS schemes into more sophisticated adaptive schemes. On the other hand, the literature lacks a systematic analysis of traditional UFLS schemes, which still present the majority within all UFLS schemes actually used in real power systems. For that reason, the probabilistic power flow is used to quantify the level of performance of many different configurations of traditional UFLS schemes (varied both in the number of shedding steps as well as their size) in the whole variety of operating conditions. With the use of probability power flow the probability density function of active-power imbalance is calculated. The obtained results enable to extract those configurations that yield the best results in most probable events and at the same time avoid giving too much attention on poor performance during less probable system conditions. The results were obtained by performing dynamic simulations on the north-western part of a Slovenian power system.


    1. 1)
      • 1. ‘Official Gazette of the Republic of Slovenia’. Available at, accessed August 2014.
    2. 2)
      • 2. ‘Continental Europe operation handbook’. Available at, accessed August 2014.
    3. 3)
    4. 4)
    5. 5)
      • 5. Tofis, Y., Hadjidemetriou, L., Kyriakides, E.: ‘An intelligent load shedding mechanism for maintaining frequency stability’, IEEE PowerTech (POWERTECH), 2013, Grenoble, 2013, pp. 15.
    6. 6)
    7. 7)
    8. 8)
    9. 9)
      • 9. Delfino, B., Massucco, S., Morini, A., et al: ‘Implementation and comparison of different under frequency load-shedding schemes’. Power Engineering Society Summer Meeting, 2001, pp. 307312.
    10. 10)
      • 10. Rudez, U., Mihalic, R.: ‘Comparison of adaptive UFLS schemes in modern power systems’. 2011 IEEE Electrical Power and Energy Conf. (EPEC), 2011, pp. 233238.
    11. 11)
      • 11. Coroiu, F., Bucatariu, I., Baloi, A.: ‘Using the Gram–Charlier expansion in power systems reliability’. 2012 Seventh IEEE Int. Symp. on Applied Computational Intelligence and Informatics (SACI), 2012, pp. 5962.
    12. 12)
      • 12. Chen, P., Chen, Z., Bak-Jensen, B.: ‘Probabilistic load flow: a review’. Third Int. Conf. on Electric Utility Deregulation and Restructuring and Power Technologies, 2008, pp. 15861591.
    13. 13)
      • 13. Cai, D., Chen, J., Shi, D., et al: ‘Enhancements to the cumulant method for probabilistic load flow studies’. 2012 IEEE Power and Energy Society General Meeting, 2012, pp. 18.
    14. 14)
      • 14. Bogovic, J., Bone, G., Mihalic, R.: ‘An improved method enabling probabilistic calculation of the power-system load-flow using the method of cumulants’, Elektroteh. Vestn., 2013, 80, (5), pp. 251257.
    15. 15)
    16. 16)
    17. 17)
      • 17. Rudez, U., Mihalic, R.: ‘Dynamic analysis of transition into island conditions of Slovenian power system applying underfrequency load shedding scheme’. IEEE PowerTech, 2009Bucharest, 2009, pp. 16.
    18. 18)
    19. 19)
    20. 20)
      • 20. Wan, C., Xu, Z., Dong, Z.Y., et al: ‘Probabilistic load flow computation using first-order second-moment method’. 2012 IEEE Power and Energy Society General Meeting, 2012, pp. 16.
    21. 21)
      • 21. Billinton Li, W.: ‘Reliability assessment of electrical power systems using Monte Carlo methods’ (Springer Science and Business Media, 1994).
    22. 22)
      • 22. Hsu, H.P.: ‘Schaum's outline of theory and problems of probability, random variables, and random processes’ (McGraw-Hill, 1997).
    23. 23)
    24. 24)
      • 24. ‘SENG’. Available at, accessed August 2014.
    25. 25)
      • 25. Azbe, V., Mihalic, R.: ‘Modelling of control of a doubly-fed machine in transient stability analysis’. 2013 Eighth Int. Conf. on Compatibility and Power Electronics (CPE), 2013, pp. 214218.
    26. 26)
    27. 27)

Related content

This is a required field
Please enter a valid email address