Adaptive underfrequency load shedding based on the magnitude of the disturbance estimation

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In this paper, a new approach to adaptive underfrequency load shedding (UFLS), a procedure for protecting electric power systems from dynamic instability and frequency collapse, is presented. It consists of two main stages. In the first stage, the frequency and the rate of frequency change are estimated by the nonrecursive Newton-type algorithm. By using the simplest expression of the generator swing equation, in the second algorithm stage, the magnitude of the disturbance is determined. The UFLS plan is adapted to the magnitude estimated, obtaining in this way a more efficient system operation during emergency conditions. Results of procedure testing are demonstrated through the dynamic simulations by using: 1) a simple three-machine test system and 2) a ten-machine New England system.

Original languageEnglish
Pages (from-to)1260-1266
Number of pages7
JournalIEEE Transactions on Power Systems
Issue number3
Publication statusPublished - Aug 2006
Externally publishedYes


  • Adaptive control
  • Dynamic simulation
  • Nonlinear estimation
  • Underfrequency load shedding (UFLS)


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