DC Link Current Control of Cascaded Current Source Converter Based Offshore Wind Farms

A new interconnecting approach for an offshore wind farm is used, where same number of cascaded pulse width modulated (PWM) current source converters (CSCs) are used on both generator and grid side. This paper presents a novel control scheme which enables maximum power acquisition from the wind for every wind turbines in the wind farm and aggregate power is equally shared by the grid side CSCs with independent active and reactive power control. The individual generators be controlled for power tracking in a way similar to that used when they are connected directly to an ac grid. Because of the variability of wind speeds due to the different locations of the wind turbines in wind farm, each unit has different dc link current requirement depends on its generated power. The reduced dc link current is generated in a way to meet the minimum dc link requirements from all the CSCs in the wind farm. The simulation results are provided to verify the proposed control scheme.