Sub-synchronous interaction in wind power plants — part I: Study tools and techniques

This is the first part of a two-paper series which investigates different modeling and simulation tools and techniques appropriate for the analysis of sub-synchronous control and torsional interaction in wind power plants. A critical review of the commonly used techniques is presented which allows identifying the three suitable candidates. These methods include frequency scanning method, the test signal method for the calculation of electrical damping provided by the wind turbine generator, and electromagnetic transient analysis which confirms the veracity of the first two methods. A dynamic frequency scanning method for the turbine side is developed which takes account of the turbine non-linearities and its active behavior. It is shown that these three tools allow capturing all the information pertinent to sub-synchronous interaction phenomena. The application of these tools and techniques on a practical power system comprising type 3 wind turbines and series compensated lines is demonstrated. Results obtained from these three methodologies are consistent and complimentary.