Study on Wideband Harmonic Instability of Wind Farm Based on the Vector Fitting Method

The distributed parameter characteristics of the feeders can easily cause wideband harmonic instability (WHI), when the distributed generation power plants (DGPP) are connected to weak grids through long transmission lines or cables. The existing studies evaluating the harmonic instability of DGPP usually utilize the lumped parameter models of feeders, which are inaccurate for the WHI analysis. However, if the distributed parameter characteristics are considered, the pole equation of the system becomes transcendental with a complex hyperbolic function, which makes it hard to determine the pole distributions. Given this, this paper proposes a vector fitting method to obtain the pole distributions in considering the distributed parameters of feeders. Thus, more accurate and complete pole distributions can be obtained, and the results for system stability evaluation are more reliable in a wider frequency range.