臺灣博碩士論文加值系統

針對輸變電系統中大型浸油式變壓器之內部部分放象現象辨識需求，本研究依據彈性波動理論及數位訊號分析技術建立一波形反算法，去除波傳過程中頻散現象對波形產生之影響，提供分析判斷部分放電型態及規模大小所需資訊。
本研究引用洩漏萊姆波之觀念，分析不同頻率及模態的波，各自對應之波傳路徑與波速，並求出能量衰減係數與時間延遲量，針對實際量測訊號修正能量衰減與時間延遲，即可得到油中音源波形。訊號修正方面，分別運用音源頻譜估算法、脈衝頻率響應法與基因演算法，反算油中音源波形，再進行波形模態辨識。經驗證利用反算所得之音源波形，可成功辨識四種不同人造音源。
使用11kV實體變壓器加壓測試，確定初始發生絕緣劣化到完全破壞之間，持續會有小規模的部分放電現象，其發生頻率與能量會隨加壓時間與電壓之增加而遞增。若能在此期間確定其部分放電音源位置、模態與規模大小，對維護電力系統有極大的助益。

In consideration of the requirement of recognition of the partial discharge (PD) phenomena in large scale oil-immerged power transformers, a waveform inversion procedure based on elastic wave theory and digital signal processing is developed in this study. To diminish the influence of dispersion relation on waveform and to provide useful information for classifying PD in power transformers, leaky lamb wave theory was introduced. It was used to find out the wave propagation and velocity of different mode and different frequency, then the attenuation and time delay were known. Using attenuation and time delay , it is possible to inverse waveform from sensor to source. In this study, three methods were used to compute the inverse waveform, spectrum inversion, impulse response, and genetic algorithm. It is successful to recognize four differenct species of artificial electrodes from inverse waveform.
Through the experiment on actual 11kV power transformer, It was known that before electric breakdown, the small PD will happen, the scale and the number of times will increase if the voltage don''t descend below the critical voltage. It is very important and achievable to detect and recognition the small PD before it breakdown.

第一章 前言1
1.1 研究動機1
1.2 相關研究2
1.3 研究目的4
1.4 內容說明4
第二章 部分放電與波傳物理現象6
2.1 部分放電之物理現象─空化氣泡機制7
2.2 油中波傳現象10
2.2.1 油中音壓變化10
2.2.2 內部結構物影響11
2.3 表面波傳現象14
2.3.1 油固介面波傳現象14
2.3.2 板波頻散現象16
2.3.3 表面結構物影響16
2.4 音源定位─四點定位法19
第三章 表面音洩波形反算理論21
3.1 波形反算理論─洩漏萊姆波21
3.2 油中音源波形反算程序25
第四章 表面音洩波形反算與辨識27
4.1 音源頻譜估算法27
4.2 脈衝頻率響應法29
4.3 基因演算法30
4.4 人造電極放電模態辨識33
第五章 驗證實驗37
5.1 表面波傳特徵驗證37
2.2 實體變壓器驗證實驗39
第六章 結論41
參考文獻42

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