Dynamic Coordination to Supplementary Damping Controllers in Heterogeneous Wind Farm to Suppress Oscillations Among Synchronous Generators

The supplementary damping controller (SDC) at the doubly-fed induction generator (DFIG) can suppress angular oscillations among synchronous generators (SGs). The existing studies see wind farm as equivalent DFIG, ignoring interaction among SDCs and DFIGs, not suitable to coordinate SDCs in heterogeneous wind farm (HWF) with only some DFIGs having SDCs. This paper proposes a dynamic coordination model to SDCs to suppress the oscillations considering the interaction due to HWF. First, the interactive currents of DFIGs are decomposed to components related to stator voltages and SDCs. Non-square interactive matrix caused by SDCs is derived to quantify impact of SDCs on non-identical DFIGs. Then by using the non-square internal model control (IMC), a two-stage model is proposed to coordinate the gains of SDCs with the interactive matrix to avoid uniform setting. Finally, to further improve suppression effect, interactive sensitivity with respect to SDC's gain is derived, based on which the analytical expression of the pseudo inverse of interactive matrix is newly derived by equating it to numerical solution derived by Moore-Penrose inverse and equating the sensitivity of the former to that of the latter, to avoid uncertain solutions of coordination model. Simulation results verify control effect of the proposed model.