Experiences on voltage dip ride through factory testing of synchronous and doubly fed generator drives

The electrical utilities have specified in their recent requirements that wind turbines have to be capable to ride through severe voltage dips without disconnecting. For the verification of the ride through capability factory and field tests are needed. In most cases a test system with fault emulation is used that will give more realistic results especially for generators that have their stator directly connected to the grid. However, care has to be taken that the impedance level of the test setup is low enough. Experimental results are presented for a 1.6 MW doubly fed generator and a 200 kW synchronous generator drive. Moreover, the problem with the reactive power measurement during ride through is discussed in the end of the paper