Sub-synchronous resonance analysis of grid-connected DFIG- based wind farms

This paper aims to research the sub-synchronous resonance (SSR) in DFIG-based wind farms connected to an infinite bus via a series-compensated transmission line. The detailed mathematical models and state matrix involving the dynamics of mechanical shaft, generator, transmission line, and the reduced-capacity converters are derived. The PI parameters of the control systems of the DFIG-based wind farm are optimized based on an improved evolutionary programming algorithm, in which all the real parts of the eigenvalues of the test system can be kept negative. Based on the IEEE first benchmark model as example, the eigen-analysis along with participation factors is performed to study the impacts of series compensation level, parameters of PI controllers, and wind speed on SSR.