Optimal Power Oscillation Damper Placement in Wind Farm to Enhance Stability Margin Based on Open-Loop Gain Perturbation Bound

Wind turbine generators, e.g., doubly-fed induction generators (DFIGs), have little inertia, thus reduce power system stability and intensify low-frequency oscillation (LFO). The LFO previously damped by the synchronous generators now may be damped by power oscillation damper (POD) at the DFIGs. The existing POD studies are for the aggregated wind farm, ignoring the difference among the DFIGs, and the POD placement at all DFIGs may be unnecessary. In this paper, the optimal placement of the PODs in wind farm to enhance the stability margin and mitigate the LFOs of power system is studied, with the following novelties, 1) The feedback loops for multi-DFIG wind farm and PODs are newly derived to show the effect of PODs on stability margin. 2) With the perturbation analysis to the open-loop gain function, the tight bound to describe the effect of POD placement on stability margin is proposed. 3) An optimization model with the bound of stability margin is proposed to place the PODs, and solved with the improved simulated annealing algorithms using the greedy search. Numerical analysis verifies the correctness of the proposed stability margin bound and the effectiveness of the optimal placement to PODs.