Low-voltage ride-through of PM synchronous wind generator under asymmetrical voltage sags with constant power

摘要

As the wind energy generation becomes more frequently employed worldwide, specific grid codes concerning power quality are required for these systems. Several countries have determined that the wind turbines cannot be disconnected from the grid during voltage sags, depending on the severity of the sags. This has pushed manufacturers to implement low-voltage-ride-through strategies in their turbines. Some grid codes not only demand that the turbine remain connected but also that it must provide active or reactive power in order to aid the recovery from the fault. This paper presents a strategy of low-voltage-ride-through that uses resonant controllers in the synchronous reference frame in order to withstand unbalanced voltage sags in a permanent magnet synchronous machine topology with full-scale power converter. It presents also the current references calculation so that the output active or reactive power can be controlled with oscillations. Simulation results are shown to demonstrate the strategy.