Clustering Effect Evaluation on Offshore Wind Power Based on Time-amplitude and Time-frequency Analysis

With large-scale offshore wind farms integrated to power systems, it becomes necessary to consider the clustering effect of wind power during planning and operation of power systems. Addition to traditional time-amplitude analysis, time-frequency analysis is also employed to evaluate the clustering effect of offshore wind power simultaneously and comprehensively. To evaluate the clustering effect quantitatively and accurately, an extensive index system is presented including normalized average output value, deviation coefficient, proportion of low output, peak-to-valley difference, smoothing coefficient, modal fluctuation rate, and frequency amplitude ratio. Consequently, in time-amplitude domain, the long-term and short-term output characteristics of single wind farm and long-term fluctuation correlation and short-term clustering complementarity of multiple wind farms are investigated. And, in time-frequency domain, variational mode decomposition (VMD) is used to decompose multiple wind power sequences to calculate the frequency range of wind power fluctuation. Finally, case study based on the practical data of offshore wind farms in Jiangsu province, China, is performed to validate the feasibility and effectiveness of the proposed evaluation scheme.