Stability Impacts of an Alternate Voltage Controller (AVC) on Wind Turbines with Different Grid Strengths

This paper studies the stability impact of alternate voltage controller’s (AVC) low-pass filter (LPF) in a wind turbine’s grid-connected source converter (VSC). A small-signal model is designed with grid-following synchronization control. More specifically, non-linear state-space was developed, including dynamics both inner and outer control loops converter, elements electrical system, as well digital time delay. An eigenvalue-based analysis gives insight into impacts outer-loop controllers. It proven that cutoff frequency AVC’s LPF affects phase-locked loop (PLL) AVC bandwidths instability, corresponding critical oscillation frequencies. phenomenon observed weak strong grids. Consequently, regions PLL bandwidth can be identified for range under study. The AVC, which are obtained from model, determined frequencies, validated through domain simulations fast-Fourier transformation (FFT) analysis.