Effect of variable speed wind turbine generator on stability of a weak grid

In this paper, we illustrate the effect of adding a hypothetical 100-MW doubly fed induction generator (DFIG) wind power plant to a weak transmission system. The effects of various wind plant load factors (100, 60 and 25% of nameplate rating) are investigated. System performance is compared to a 100-MW conventional synchronous generator interconnected at the same location. The conventional generator is installed some distance away. The simulations demonstrated that DFIG generators provide a good damping performance under these conditions. These results support the conclusion that modern wind power plants equipped with power electronics and low-voltage ride-through capability, can be interconnected to weak power grids without reducing stability. To conduct the studies, we selected an area of the Western Electricity Coordinating Council power system that is electrically far from major generation centers and is-weakly connected to the bulk transmission system. The area contains large motor loads. We observed the dynamic response of large motors in the vicinity, especially their ability to ride through fault events. The studies were conducted using positive sequence phasor time-domain analysis.