本論文係針對以雙饋式感應發電機為主之離岸式風場與永磁式同步發電機為主之離岸式風場整合後，經由高壓直流傳輸系統並聯至市電之架構為研究目標，並比較此類混合離岸式風場採用高壓直流傳輸系統進行功率潮流控制以及穩定度改善之影響。本論文於三相平衡系統下利用交直軸等效電路模型，分別建立雙饋式感應發電機為主之離岸式風場、永磁式同步發電機為主之離岸式風場以及電壓源型之高壓直流傳輸系統等模型，並利用極點安置法設計高壓直流傳輸系統之比例-積分-微分阻尼控制器。本論文於穩態特性方面，分析風速及電網電壓變動等情況下對系統穩定度特性之影響。在暫態及動態模擬方面，完成了風速變動、轉矩干擾以及市電端發生三相短路故障等模擬結果。由穩態、動態及暫態之模擬結果分析得知，高壓直流傳輸系統能夠有效地控制混合離岸式風場並聯市電之功率潮流以及改善該風場系統於不同干擾下之穩定度。

This thesis presents the analyzed results of power-flow control and stability improvement of an integrated doubly-fed induction generator (DFIG)-based offshore wind farm (OWF) and permanent-magnet synchronous generator (PMSG)-based OWF connected to a large utility grid through a high-voltage direct-current (HVDC) link. The q-d axis equivalent-circuit model is used to establish the models of the studied DFIG-based OWF, the PMSG-based OWF, and the HVDC link under three-phase balanced loading conditions. A proportional-integral- derivative (PID) damping controller of the HVDC link is designed by using a pole-assignment approach based on modal control theory. Steady-state characteristics of the studied system under different values of wind speed and grid voltage are examined. Dynamic results and transient simulations of the studied system subject to a wind-speed disturbance, a torque disturbance, and a three-phase fault at the power grid are also carried out. It can be concluded from the simulation results that the proposed HVDC link joined with the designed damping controller are very effective to control the power flow and improve the stability of the studied integrated OWF systems.

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