本論文係研究採用統一功率潮流控制器來抑制混合蒸汽渦輪機以及風力渦輪機發電系統之次同步共振現象。本論文中第一個研究架構為原始美國電機電子工程師學會提出之第二標準模型、第一系統之同步發電機系統以及將雙饋式感應發電機為基底之風場取代系統中同步發電機之架構；第二研究系統架構為整合原始第二標準模型、第一系統模型與離岸式風場，經串聯電容補償輸電線連接至無限流排，探討當離岸式風場與同步發電機系統併入後，對原始系統之次同步共振現象。本論文於三相平衡下，利用交-直軸等效電路建立模型，其中包含：同步發電機、雙饋式感應發電機為基底之離岸式風場以及統一功率潮流控制器等系統模型，並利用極點安置法設計統一功率潮流控制器之比例-積分-微分阻尼控制器。在系統小訊號穩定度方面，針對傳輸線路補償比、同步發電機輸出實功率、同步發電機輸出端電壓、功率因數及風場風速變動等工作點變化之頻域特徵值分析；在系統動態與暫態模擬分析部分，完成轉矩干擾、風速變動、風速干擾及三項短路故障等模擬結果。由系統小訊號穩定度、動態及暫態模擬結果可以得知，當加入統一功率潮流控制器結合比例-積分-微分阻尼控制器後，能使系統回復至穩定，並有效抑制系統次同步共振現象

This thesis presents the suppression results of subsynchronous resonance (SSR) in power systems with a steam-turbine system and a wind-turbine generation system using a unified power flow controller (UPFC). The first studied system uses the Second Benchmark Model, system-1 of Institute of Electrical and Electronic Engineers (IEEE), USA while a doubly-fed induction generator (DFIG)-based wind farm is used to replace the synchronous generator (SG) in the IEEE second Benchmark Model, system-1. The second studied system is based on the IEEE Second Benchmark Model, system-1 joining with a DFIG-based offshore wind farm (OWF). The d-q axis equivalent-circuit model under three-phase balanced loading conditions is used to establish the studied systems including the mass-spring-damper system, the SG, the DFIG-based offshore wind farm, the UPFC, and other system models. A proportional-integral-derivative (PID) damping controller of the UPFC is designed by using pole-assignment approach based on modal control theory. Small signal stability characteristics of the studied system under different series compensation ratios, output active power, the terminal voltage, power factor of the SG, and wind speed of the OWF are performed. Nonlinear model time-domain simulations under torque disturbance of the SG, wind speed variation, wind speed disturbance, and three short-circuit faults are also carried out. The simulation results show that the proposed UPFC joined with the designed damping controller are effective to suppress the SSR of the studied power systems.

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