台灣的配電系統上經常採用兩個單相變壓器繞組的U-V和V-V連接來供電三相負載，這兩種類型的變壓器連接方式將導致配電系統的三相電壓不平衡，進而使中性線電流增加而導致接地電驛跳脫，同時三相不平衡供電也會造成額外的輸配電線路損失及降低交流馬達的運轉效率，故本論文提出採用配電型靜態同步補償器來改善系統三相電壓不平衡的特性。本論文系統架構一係以IEEE四節點之測試饋線為基礎，利用配電型靜態同步補償器改善變壓器因U-V/V-V連接所造成之電壓不平衡；系統架構二係以實際台電配電系統架構為基礎，分析一具配電型靜態同步補償器安裝位置以及變壓器繞組改裝對電壓不平衡率的影響，本論文由模擬結果驗證所提出方法的可行性。

The U-V or V-V winding connection of two single-phase distribution transformers is widely used in most utility companies including Taiwan Power Company (TPC) to deliver power to various three-phase loads. Such special winding connection can cause three-phase voltage unbalance which leads to the trip of ground relay, extra power loss on distribution lines, and reduced efficiency of induction motors. This thesis proposes a distributed static synchronous compensator (D-STATCOM) to decrease the voltage unbalance due to U-V or V-V winding connection of distribution transformers. System configuration 1 is based on the IEEE 4-node test feeder with U-V or V-V winding connection of transformers while the D-STATCOM is proposed to reduce three-phase voltage unbalance. System configuration 2 is based on a distribution system of TPC while the location of the D-STATCOM and the modification of U-V/V-V winding connection of transformers are carried out. The simulation results show that the use of the proposed D-STATCOM to reduce three-phase voltage unbalance due to U-V or V-V winding connection of distribution transformers is feasible.

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