本文旨在提出一套適用於三相獨立供電模式變流器，對共同耦合點(Point of Common Coupling, PCC)提供不平衡及非線性負載之電壓自動補償技術。理想上，供電系統負載側的變流器應提供固定振幅、頻率的弦波電壓於PCC。少了市電輔助，獨立供電模式的PCC電壓容易受到負載種類影響，非線性負載可能產生電壓諧波而降低電壓品質。為維護供電品質，本研究採用比例諧振控制器(PR controller)搭配諧波補償機制。此方法需要在使用諧振控制器前獲得電壓的諧波資訊，透過諧振控制器在特定諧波頻率下操作來降低電壓的諧波。本研究利用快速傅立葉轉換(Fast Fourier Transform, FFT) 得到電壓的諧波資訊，比例諧振控制器便能針對不同的諧波頻率進行辨識與補償，達到自我修正電壓的功能。最後，本研究建構了三相獨立供電系統的測試平台，透過不同的負載試驗，證明該控制策略能有效改善供電品質。

In this thesis, a three-phase inverter providing automatic voltage compensation for unbalanced or nonlinear load under stand-alone operation is presented. An ideal load-side inverter should provide constant amplitude, frequency, and sinusoidal voltage at point of common coupling (PCC). Without the stiff sinusoidal voltage support by grid, voltage quality at PCC is heavily affected by the type of loads. The nonlinear loads could produce voltage harmonics that degrade voltage quality. To maintain voltage quality at certain level, a proportional-resonant (PR) controller embedded with automatic harmonic compensation scheme is proposed. Harmonic components of voltage can be neutralized by resonant controllers that are tuned at harmonic frequencies. This method requires that the voltage harmonics need to be identified before resonant controllers are applied. Using the fast Fourier transform (FFT), dominant harmonic components could be identified for the PR controller to compensate harmonics at some resonant frequencies. The effectiveness of proposed voltage compensation strategy is verified through experiments on a testbed of the three-phase stand-alone system.

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