DC voltage control in off-shore wind farms with distributed diode rectifier units

Distributed diode rectifier units have been proposed as a robust and cost efficient solution for the connection of large off-shore wind farms to HVDC links. However, since the diode rectifier platforms are connected in series with cables of varying distances, their dc-side voltage might not be the same in all diode rectifier platforms. This paper introduces a diode rectifier platform dc-voltage balancing control to cancel the aforementioned unbalanced. Balanced operation has been shown by means of detailed PSCAD simulations, considering a wide range of power generation unbalance between the wind power plants connected to the HVDC diode rectifier platforms. Moreover, the proposed balancing control has shown a very good dynamic performance.