Precise ROCOF Estimation Algorithm for Low Inertia Power Grids

He Yin, Yuru Wu, Wei Qiu, Chujie Zeng, Shutang You, Jin Tan, Andy Hoke, Cameron Kruse, Brad Rockwell, Kelcie Kawamura, Yilu Liu

Research output: Contribution to journalArticlepeer-review

15 Scopus Citations


The precise estimation of Rate Of Change Of Frequencies (ROCOFs) in a generation trip event can be helpful on power system inertia estimation, fast system response, and accurate event capturing. However, the ROCOF estimations from the existing Synchronized Measurement Devices (SMDs) are usually simply calculated by the finite difference between two adjacent frequency measurement points. The ineluctable noises, disturbances, and spikes from real-world frequency measurements can bring large dynamics to the ROCOF estimation and thus can result in an inaccurate estimation of the initial ROCOF. This issue becomes more serious when the target power grid has low inertia and a large amount of distributed energy sources are deployed. To address this issue, a precise ROCOF estimation algorithm is designed based on least square method with flexible window size. In addition, a median filter is also designed and applied on the frequency measurements before using the proposed algorithm. The window size and thresholds in the proposed algorithm are determined with historical event data analysis. The proposed algorithm is deployed in a low cost, flexible, and distribution level universal grid analyzer (UGA) platform. Multiple experiments are conducted in both a laboratory and the Hawaiian Islands to verify the effectiveness of the proposed algorithm.

Original languageAmerican English
Article number107968
Number of pages10
JournalElectric Power Systems Research
StatePublished - 2022

Bibliographical note

Publisher Copyright:
© 2022 Elsevier B.V.

NREL Publication Number

  • NREL/JA-6A40-82669


  • Event capturing
  • Frequency estimation
  • Low inertia power system
  • Rate of change of frequencies
  • Synchronized measurement devices


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