在科技發展迅速，用電量有增無減的現代，傳統集中式發電與電網穩定性的問題，比起過往更受到重視，分散式發電及微電網等概念被提出，用來解決這些問題。再加上近年來各國積極發展再生能源，而換流器具有將直流電轉換成交流電的功能，能將再生能源所產生的電能送入市電。當電網連接至電感性、電容性負載時，會造成電網電壓與電流之間的相位差而產生虛功。虛功會增加電網電流之振幅，導致線路壓降提高，影響電網電壓穩定性；同時也增加線路損失，造成電能傳輸效率降低，再加上傳統虛功補償電容無法應用於負載變動的場合，因此本文以數位訊號處理器實現單相併網型全橋換流器，並加入虛功補償功能。根據電網需要提供電感性或電容性虛功，提高整體系統功率因數，降低傳輸損失。輸出端採用LCL型濾波器，濾除開關高次諧波，避免併網時造成電網負擔；並使用二階廣義積分器鎖相迴路取得電網振幅及相位資訊，用以產生電壓命令，併網時採用定功率控制，此時電網主導輸出電壓，因此將控制環由電壓電流雙環切換至單電流環。最終以電路模擬軟體PSIM驗證控制法及電路參數，建構出單臺輸入直流電壓400 V，輸出交流電壓230 V，額定功率1.65 kW具虛功補償單相併網型換流器。

In the rapidly evolving world of technology and increasing electricity demand, the issues surrounding traditional centralized power generation and grid stability have become more critical than ever before. Concepts like distributed generation and microgrids have emerged as potential solutions to address these challenges. Moreover, with the global push towards renewable energy sources, inverters capable of converting direct current to alternating current have become vital for integrating renewable energy into the grid. When the grid is connected to inductive or capacitive loads, a phase difference between grid voltage and current leads to the consumption of reactive power, resulting in an increase in grid current amplitude and causing voltage instability. This, in turn, contributes to increased line losses and reduced transmission efficiency of electrical energy. The traditional method of using capacitors for reactive power compensation is inadequate for load variations, necessitating the implementation of digital signal processors to realize single-phase grid-tied full-bridge inverters with reactive power compensation. The primary objective of this study is to provide inductive or capacitive reactive power as per the grid requirements to enhance the overall system power factor and reduce transmission losses. An LCL-type filter is employed at the output to eliminate high-order harmonics from switching and prevent grid burden during grid-tied operation. Additionally, a second-order generalized integrator phase-locked loop is utilized to obtain grid voltage amplitude and phase information for generating voltage commands. During grid-tied operation, a constant power control strategy is applied, with the grid taking the lead in determining the output voltage. Consequently, the control loop switches from a dual-loop to a single current loop. Finally, the control method and circuit parameters were validated using the circuit simulation software PSIM, resulting in the construction of a single-unit, single-phase grid-tied inverter with reactive power compensation. The system was designed to accept an input DC voltage of 400 V and produce an output AC voltage of 230 V, with a rated power of 1.65 kW.

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