Susceptibility of Wind Turbines to Sub-synchronous Control and Torsional Interaction

This paper investigates the risk of sub-synchronous interaction in wind power plants. Time-domain PSCAD/EMTDC simulation case studies are conducted for the most pessimistic operating condition where the wind power plant becomes radially connected to a weak ac system through a series compensated ac line. Wind turbines of type 1-4 designs are investigated from a sub-synchronous control interaction standpoint. Two different variations of type 3 turbines are considered. Further the susceptibility of type 3 turbine with regard to sub-synchronous torsional interaction is discussed. The outcome of these case studies helps identifying the turbine types which are immune to sub-synchronous interaction problems, and those which could, under some circumstances, be susceptible to sub-synchronous interaction issues.