三相併網太陽能換流器之直流匯流排電壓漣波消除方法

Abstract

本論文提出了一種新的控制方法，即三相併網太陽能電力系統的直流匯流排電壓漣波消除方法，它可以消除不平衡電網條件下的直流匯流排漣波。當電網故障發生時，由於不平衡電壓，傳統的太陽能換流器會產生兩倍市電頻率振盪的實虛功，導致直流匯流排電壓波動，對太陽能系統的穩定性造成不利影響。除此之外，注入電網的電流可能會失真。 本文提出的直流匯流排電壓漣波消除方法的目的是消除不平衡電網下的直流匯流排電壓漣波，並且不需要額外的電路。此外，前級轉換器和後級換流器之間的通信機制是不必要的。本論文介紹此方法的操作原理和數學推導，並從電腦模擬結果和1kVA原型機實作來驗證該方法的可行性。

A new control method, the dc-link voltage ripple cancellation (DVRC), for three-phase grid-tied PV power systems is proposed to cancel the dc-link ripple during unbalanced grid conditions. When a grid fault occurs, the conventional PV inverter system will generate double-line frequency active/reactive power due to the unbalanced grid voltage. It causes the dc-link voltage fluctuating, which is bad for PV system's stability. Moreover, the current injected to the grid may suffer from distortion. The objective of the proposed DVRC method is to cancel the dc-link voltage ripple in an unbalanced grid without the need of additional circuits. Besides, communication mechanisms between the front-end converter and the rear-end inverter are not necessary. Operational principles and mathematical derivations of the proposed DVRC are presented in this thesis. Both simulation results and hardware verifications obtained from a 1kVA prototype circuit demonstrate the feasibility of the proposed DVRC method.