An Inductive Filtering-Based Parallel Operating Transformer With Shared Filter for Power Quality Improvement of Wind Farm

This article proposes an inductive filtering-based parallel operating transformer with a shared filter to improve the power quality at the grid-connected step-up station of a wind farm. Only a set of the shared inductive filter is configured to serve for two wind farms (two harmonic sources). The proposed transformer together with the shared filter has the merits of less installation space, higher equipment utilization, and better filtering performance compared with the conventional scheme. The three-phase mathematical model of the step-up station is established. Its simplifying circuit is obtained considering the symmetry and asymmetry parameters of the transformer impedance. The filtering mechanism, operating characteristics, and the realization condition of satisfactory filtering performance are further revealed. At last, the proposal is verified to be feasible and effective by means of simulation results and field measurements.