Equivalent modelling of wind farm for small‐signal stability analysis in weak power system

Abstract

This study proposes a novel equivalent modelling method of wind farm (WF), which can be used for small‐signal stability analysis and researches on damping control of low‐frequency oscillation. First, a complete WF model described with a set of differential algebraic equations is established, then its linearised model is obtained at one of the steady‐state operating points. Next, the eigenanalysis and the modal participation factor (MPF) analysis methods are adopted to evaluate the low‐frequency oscillation modes and the corresponding modal participation in each wind turbine generator (WTG). A feature vector for each WTG, describing its oscillation characteristics, is extracted based on the MPFs. Afterwards, all WTGs are clustered into some groups via a clustering algorithm, then the WTGs in the same groups are aggregated into a single WTG, using the weighted summation method. Furthermore, the criterion for the validity of the equivalent model is studied. The proposed modelling and validation methods are verified by simulations.