Multi-Time-Scale Analysis on Power Grid Frequency Characteristics

Fluctuations in grid frequency occur across multiple time scales. An understanding and analysis of these characteristics are crucial for the design and implementation of power system operational and regulatory mechanisms. This study proposed a multi-time-scale analysis framework for investigating grid frequency fluctuation characteristics, focusing on three major regional power grids: Great Britain, Continental Europe, and Northeast China. Adaptive multitaper spectral estimation based on the Local Curvature-Smoothness Index (LCSI) revealed characteristic time scales of grid frequency fluctuations at 1 minute, 15/30/60 minutes, and 12/24 hours, exhibiting notable regional differences. The diurnal load rhythms, variations in regional dispatch and regulation mechanisms, and the design of the electricity market were posited as key drivers of these differences. Further analysis using continuous wavelet transform-based time-frequency analysis uncovered the daily patterns of grid frequency fluctuation components across typical time scales in the time domain. The study also found that the daily average fluctuation trends of the system load variation and the typical scale components of the grid frequency exhibit strong consistency during specific periods, indicating a close connection between them.