Application of Model Order Reduction to a DFIG-Based Wind Farm in the Chilean System

This paper presents the application of a model order reduction method (Balanced Truncation, BT) to the Chilean Central Interconnected Subsystem (CCIS), where rising penetration of wind power is increasing the number of state variables in power system dynamic studies. We use BT to approximate the dynamic models of wind farms composed of doubly-fed induction generators (DFIG), considering plant-level control schemes such as voltage supervisory control and frequency regulation participation. Time-domain simulations for a real DFIG-based wind farm connected to the CCIS were conducted for a step change in the set-point of the plant-level voltage supervisor control and for changes in wind speed. Simulation results showed that the reduced-order dynamic models were capable of tracing the signal, retaining the oscillations, and reaching the same final values than the full-order model. Furthermore, in our application to the Chilean system they could run in a fraction of the time needed to simulate the full non-linear wind farm models. Thus, the reduced-order model can offer a good compromise between computational effort and accuracy in time-domain simulations.