DFIG wind turbine under unbalanced power system conditions using adaptive fuzzy virtual inertia controller
Keywords: adaptive Virtual Inertia Controller (VIC), Doubly-Fed Induction Generator (DFIG), frequency stability, inter-area oscillations, Maximum Power Point Tracking (MPPT), Wind Turbine Generator (WTG)
AbstractThe Doubly-Fed Induction Generator (DFIG) based Wind Turbines Generator (WTG) with traditional Maximum Power Point Tracking (MPPT) control provides no inertia response under system frequency events. Recently, the DFIG wind turbines have been equipped with the Virtual Inertia Controller (VIC) to enhance the frequency stability of the power system. However, the conventional VICs with fixed gain have negative effects on the inter-area oscillations of regional networks. To cope with this drawback, this paper proposes a novel adaptive VIC to improve both the inter-area oscillations and frequency stability. In the proposed scheme, the gain of the VIC is dynamically adjusted using fuzzy logic. The effectiveness and control performance of the adaptive fuzzy VIC is evaluated under different frequency events such as loss of generation and three-phase fault with load shedding. The simulation studies are performed on a generic two-area network integrated with a DFIG wind farm, and the comparative results are presented for these three cases: DFIG without VIC, DFIG with fixed gain VIC, and DFIG with adaptive fuzzy VIC. The results confirm the ability of the proposed adaptive fuzzy VIC in improving both the interarea oscillations and frequency stability of the system.