本研究旨在提出最大及最小短路電流的合理計算條件。由於目前國外計算短路電流的方法不盡相同，且IEEE及IEC等國際標準的計算方法亦未相同，本論文遂於研究過程中蒐集IEEE及IEC的短路電流計算方法，並探討台灣電力、韓國電力、關西電力、九州電力(台電、韓電、關電、九電)等總共四家電力公司的計算方法之差異，據此提出最大及最小短路電流之合理計算條件及其計算流程。本研究另以台電系統為例，進行檢討試算並對台電公司現行的計算方法提出檢討。
在最大短路電流計算方面，蒐集IEEE與IEC的相關標準資料，探討最大短路電流的諸多影響因素：直流衰減、交流衰減、斷路器的接點分離時間以及電壓因數等；亦蒐集英國電業建議的計算標準草案（ER G74）。以之與台電的現行計算準則（包括計算公式）相比較。數值驗證結果顯示：依台電現行有關直流衰減計算公式的計算結果，與依據IEEE標準的計算結果相近。本研究進一步比較四家電力公司現行的計算方法，以台電系統為對象，進行試算：試算結果顯示；台電現行的計算方法有必要予以修改，俾降低其最大短路電流值。
在最小短路電流計算方面，本研究提出統計分析法及最低負載法來計算全年最小短路電流值。統計分析法乃透過抽樣方式，以全年之小時短路電流分佈累積機率為5%所對應的短路電流值，稱為全年最小短路電流值；最低負載法乃由既有的全年負載分佈中(由低至高)取出對應於累積機率第5％的負載量時點，並以此時點之機組組合所計算出之短路電流稱為全年的最小短路電流值。本研究並根據台電現行的停機、停線準則進行計算，以之與韓電、九電及關電的計算方法相比較；根據計算結果，台電現行的最小短路電流計算值在四家電力公司當中較為偏高，遂建議予以降低，經比較統計分析法、最低負載法，建議台電採用最低負載法作為最小短路電流的計算方法。
本研究除探討一次輸電系統的最小短路電流計算方法，亦針對二次輸電系統的最小短路電流計算方法進行數值分析。據之對於台電的現行方法提出建議。

This thesis presents the methodologies, tailored to the Taipower system, for calculating the maximum and the minimum three-phase short-circuit currents (SCC). By referring to the Korea、the Kyushu and the Kansai electric utilities, which have systems similar to Taipower, we compare the calculation rules of these three power utilities with the rules of Taipower and test all rules numerically on the same Taipower system data. Based on the numerical results, the thesis suggests revisions to the Taipower calculation rules.
With respect to the maximum SCC, the thesis compares Taipower’s calculation rules with the IEC and IEEE as well as with the draft document(ER G74) proposed by the British power industry. The comparison accounts for all the influential factors on the calculation of the maximum SCC, such as decaying dc, decaying ac, the contact parting time for circuit breaker, voltage factor etc.. According to the numerical test results, the calculation formula for the decaying dc, adopted presently by Taipower, is acceptably close to that by the IEEE standard. The numerical comparison of Taipower rules with those of the above three power utilities further demonstrates the necessity of revising Taipower rules for a reduction on the maximum SCC values.
As to the calculation for the minimum SCC, the thesis suggests the use of system SCC corresponding to the cumulative probability at 5% for the system hourly load distribution, as the minimum SCC for the year under evaluation. For comparison, the thesis also calculates the SCC on basis of Taipower’s present rules which accounts for the disconnection of system generators and transmission lines and transformers. The numerical comparison of Taipower rules with those of Korea、Kyushu and Kansai reveals that the SCC values resulted from Taipower rules, are among the highest of the four power utilities. Thus the thesis suggests Taipower revise the present rules by adopting the aforementioned SCC calculation approach which is based on the 5% probability for the system hourly load distribution throughout the year for calculation of the yearly minimum SCC. Before making this suggestion, we had surveyed the hourly SCC distribution throughout the year and denoted the SCC corresponding to the cumulative probability at 5% for the distribution as ISC,5%. The above suggestion has been made after comparing the ISC,5% with the SCC calculated on basis of the minimum(5%) load.
In addition to the primary transmission, this thesis also presents the results of numerical analysis on the calculation of minimum SCC for the secondary transmission system. On basis of the results, we then make suggestions on the present Taipower rules for the minimum SCC calculation for the secondary transmission system.

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