臺灣博碩士論文加值系統

隨著電力需求的增加，電力系統也日益複雜，為了供給龐大的電力用戶，發電容量亦隨之增加。然而電力系統上的高電壓與大電流是無法直接利用儀表量測以及利用此高電壓與大電流進行保護偵測。因此，需要適當的變比器將此高電壓與大電流轉換成一個適當值。變比器包含比流器與比壓器等兩種型式，其中比流器係將大電流轉換成小電流；另一為比壓器係將高電壓轉換成低電壓。但是，當電力系統發生故障，此故障電流流過比流器鐵心時，因故障電流含有過大的直流成份會使得比流器的鐵心發生飽和的現象。若鐵心一旦發生飽和現象時，將會導致鐵心的激磁電流迅速的增加，並造成比流器二次測的電流產生失真的現象，並使量測儀表產生量測誤差與電驛產生誤動作。
本篇論文擬利用雙輸入描述函數法以及暫態描述函數法來計算鐵心飽和後的等效導納值，即可分析比流器二次測電流失真的現象。本文擬以Matlab軟體來撰寫模擬分析程式，並驗證本方法的正確性。

As power systems have grown both in complexity and the increased degrees of fault current. Power system protective relays are playing an important role than before. They require reproduction of the primary current and voltage accurately when faults occur on the system. However, CTs may saturation due to the malfunctions of power systems because of the property of iron-core of CT is non-linearity once CT had saturated, the exciting current of CT would be huge and the secondary current would be distorting. This paper presents the new methods to estimate the transient exciting current of CTs by dual-input describing function (DIDF) and transient describing function (TDF). The proposed algorithms find out the relationships of the flux and exciting current. According to the results of above the accurate transient exciting current could be estimated.

誌謝 ……………………………………………………………………………...i
中文摘要 …………….……………………………………………………………….ii
Abstract …………………………………………………………………………….iii
目錄 ……………………………………………………………………………iv
圖目錄 ……………………………………………………………………………vi
第一章 緒論………………………………………………………………………..1
1.1 前言……………………………………………………………………….1
1.2 文獻研討………………………...………………………………………..5
第二章 故障(暫態)電流分析………………………………………………….…..7
2.1 故障電流的分析………………………………………………...………..7
2.2 影響故障電流的因素…………………………………………...………11
第三章 雙輸入描述函數法(DIDF)與暫態描述函數法(TDF)簡介……………..13
3.1 描述函數法的基本概念……………………………………………..….13
3.2 雙輸入描述函數法……………………………………………………...17
3.3 暫態描述函數…………………………………………………..……….21
第四章 比流器簡介…………………………………………………………...….23
4.1 比流器的構造…………………………………………….……………..23
4.2 影響比流器準確之因素…………………………………...……………29
4.3 比流器之暫態測試方法……………………………………….………..31
第五章 比流器鐵心之等效導納及激磁電流……………………………………34
5.1 理想的飽和鐵心等效導納…………………………………………….…36
5.2 雙斜率飽和鐵心之等效導納…………………………………………….41
5.3 二次側電流補償……………………………………………………….…46

第六章 模擬結果與討論…………………………………………………………..48
第七章 結論………………………………………………………………………..64
參考文獻……………………………………………………………………………..65

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