Short circuit signatures from different wind turbine generator types

Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay of the protections. The following wind turbine generator during faults have been studied: (i) induction generator, (ii) induction generator with variable rotor resistance (iii) converter-fed rotor (often referred to as DFIG) and (iv) full scale converter. To make a clear comparison and performance analysis during faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant, with a synchronous generator, has been simulated. This paper addresses the difficulties that distance or overcurrent relays can experience when they are used in wind power plants. Whereas the short circuit contribution from power plants with synchronous generators can be calculated on the basis of the machine parameters alone, for wound rotor asynchronous and full scale generators power plants, the converters or rotor circuitry representation have to be taken into account for short circuit current studies and relay settings.