Effect of wind speed variation on the short-circuit contribution of a wind turbine

This paper investigates the effect of wind speed variation on short-circuit current contribution from a fixed-speed wind turbine. The focus is on fixed-speed wind turbines since this type of wind turbines can contribute fault currents as high as 6 or more times the rated current. The study is motivated by the fact that wind speed variation affects the internal voltage of the generator. As a result, if a fault occurs when the internal generator voltage is maximum, the fault current will be maximum. When the internal voltage is minimum, it will result in minimum short-circuit current. Hence, the objective in this paper is to study how significant this variation in fault current is with respect to the protective device settings calculated from the IEC 60909 Standard. Although this Standard has been developed for traditional power systems, it is a common practice to use it in networks interconnected with distributed generation. Five comprehensive case studies have been conducted. For each case study, the maximum and minimum fault current is calculated using the IEC Standard 60909 and compared with simulation results at different wind speeds.