| Title |
Compensation of Unbalanced PCC Voltage in an Off-shore Wind Farm of PMSG Type Turbines |
| Authors |
Ja-Yoon Kang ; Dae-Su Han ; Yong-Sug Suh ; Byoung-Chang Jung ; Jeong-Joong Kim ; Jong-Hyung Park ; Young-Joon Choi |
| Keywords |
Unbalanced grid; PCC; PMSG; Converter; Wind power system; Negative sequence current |
| Abstract |
This paper proposes a control algorithm for permanent magnet synchronous generators with a back-to-back three-level neutral-point clamped voltage source converter in a medium-voltage off-shore wind power system under unbalanced grid conditions. Specifically, the proposed control algorithm compensates for unbalanced grid voltage at the PCC (Point of Common Coupling) in a collector bus of an off-shore wind power system. This control algorithm has been formulated based on symmetrical components in positive and negative synchronous rotating reference frames under generalized unbalanced operating conditions. Instantaneous active and reactive power is described in terms of symmetrical components of measured grid input voltages and currents. Negative sequential component of AC input current is injected into the PCC in the proposed control strategy. The amplitude of negative sequential component is calculated to minimize the negative sequential component of grid voltage under the limitation of current capability in a voltage source converter. The proposed control algorithm enables the provision of balanced voltage at the PCC resulting in the high quality generated power from off-shore wind power systems under unbalanced network conditions. |