目前我國再生能源併聯電力系統之規範為「台灣電力公司再生能源發電系統併聯技術要點」，至今國內已有許多研究報告針對該要點規定之電氣參數做適切地調和，最為常見的參數有電壓變動、併網容量、孤島運轉和電力逆送，這些穩態運轉分析皆為發展初期著重之要項。隨著再生能源併網容量的急遽增加，其穿透率(penetration)已不容小覷，當中最顯著的能源類型為風力發電。以往在電力系統發生故障時，受影響之風機會即時跳脫，藉以得到對風機的最大保護。但是在高穿透率下，倘若風機隨故障發生而跳脫，電力系統的暫態穩定度會因此受到波及，甚至造成整個系統的崩潰。為此各國電力公司紛紛制訂低電壓穿越(low voltage ride through, LVRT)規範，規定風機須於系統故障發生時，維持特定時間的併網，以支持系統度過故障。
本論文將著重在為我國併聯技術要點中低電壓穿越規範之電氣參數調和，以利電力系統之穩定運轉和再生能源之產業發展。為了解風機在低電壓時所受之影響，論文中使用Matlab/Simulink所提供之風機參數，模擬直接併網型鼠籠式感應發電機(directly coupled squirrel cage induction generator, DCSCIG)及雙饋式感應發電機(doubly-fed induction generator, DFIG)在電壓驟降時的暫態響應。所模擬之電壓驟降種類分別有三相、兩相和單相，而電壓驟降程度分別有0.9pu，0.5pu和0.15pu。
由模擬結果可以發現DCSCIG在電壓驟降時所受之影響主要在於因輸入輸出功率不匹配造成轉子轉速的劇增，對風機機械結構造成負擔以及運轉時需吸收虛功率。而DFIG因轉子側透過電力電子轉換器與電網連接，且電子元件耐壓耐流不高，容易因低電壓造成的轉子過電流而損壞。因此本文特別針對DFIG電力電子轉換器中的直流電容電壓，找出其自故障發生至超出限制值的時間，並以此為根據提出適合DFIG的低電壓穿越規範之建議。

The grid code for renewable energy currently used in Taiwan is “Grid Code of Renewable Energy of Taiwan Power Company.” There have been many studies on how to properly harmonize the parameters in the grid code so far and the most common parameters are voltage variation, installation capacity, islanding and reverse power flow. The analysis of these parameters is of great importance at the early stage of developing renewable energy. With the rapid increase of installation capacity of renewable energy, the penetration shouldn’t be thought little of anymore, this is especially true when it comes to the wind power generation. The wind turbines used to be tripped off when influenced by the fault in the system to acquire the optimum protection of wind turbines, but with higher penetration the stability of the system could be disturbed or the system could breakdown if the wind turbine were tripped off when the fault take place. Therefore, utilities from every country start drawing up regulation which requires that the wind turbine should remain connected to the grid when a fault takes place in the system to help the system through the fault. Such requirement is known as low voltage ride through (LVRT).
The primary goal of this thesis is to harmonize the parameters of LVRT for the grid code of Taiwan and to make benefit for steady operation of power system and development of renewable energy industry. In order to completely understand the effect that a voltage sag has on wind turbines, the transient responses of directly coupled squirrel cage induction generator(DCSCIG) and doubly-fed induction generator(DFIG) are simulated by using Matlab/Simulink. The voltages sags are classified into three types which are three phase voltage sag, two phase voltage sag and single phase voltage sag, and the voltage sag level will be decreased from 0.9pu to 0.5pu and then to 0.15pu.
From the simulation result, the main problem that the DCSCIG encountered during a voltage sag is the requirement of reactive power for the operation of induction generator and the rapidly increased rotor speed which adds burden on the mechanical structure of the wind turbine. As for DFIG, the over current in the rotor induced by the voltage sag could damage the power electronic device easily for they are vulnerable and can not withstand such high voltage and high current therefore, the thesis proposes a suggested LVRT characteristics according to the time when the dc-link voltage excesses its limit at different voltage sag level after the fault.

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