具低電壓穿越能力之三相市電併聯PV換流器

Abstract

當市電發生不平衡電壓驟降時，市電併聯換流器輸出至市電的功率將會產生二次諧波。本文主旨提出使用拉格朗日乘數法來計算電流命令，使太陽發電系統具有低電壓穿越的能力，也能利用格朗日乘數法所計算出的電流命令，來調整實功及虛功的二次諧波。本文所提出的電流命令方法將會結合控制策略，經由電腦模擬來驗證本文所提出的控制法則。

When the grid experiences unbalanced voltages sag, the output power of the grid-connected inverter will have second harmonics. The objective of this thesis is to propose a new control scheme based on Lagrange multiplier method to calculate the current commands for the Photovoltaic (PV) inverter with the low-voltage ride-through (LVRT) capability. The current commands can control the second harmonics in the output power of the grid-connected inverter. The proposed method can combine with the maximum current amplitude control (MCAC) strategy. Computer simulations are shown to verify the performance of the proposed control scheme.