- 學位論文
69kV輸電鐵塔接地電極高頻阻抗特性模擬與試驗
Simulation and Test on The Ground-Electrodes High-Frequency Characteristics of 69kV Transmission Tower
摘要
接地電極係為電力系統接地的基礎，當輸電鐵塔被落雷擊中時，雷擊電流經由鐵塔洩放，可避免鐵塔因地電位昇高而使輸電線發生逆閃絡。但是一般興建地網時，多以低頻電源對地網進行量測，並未量測接地電極的高頻阻抗特性，而雷擊電流具有高頻特性，因此我們須要對鐵塔接地電極的高頻阻抗特性進行研究。 電力系統的雷擊特性模擬，主要使用電磁暫態軟體ATP Draw，將接地電極表示成為等效RLC 電路模型後，運用ATP 進行分析，但模型參數仰賴經驗。本論文可分為兩個部份，第一部份係利用「固定頻率之參數估計法」， 運用CDEGS(Current Distribution Electromagnetic Fields, Grounding and Soil Structure Analysis)，模擬地網注入衝擊突波電流，可得到接地電極內的接地導體電流分佈與地電位昇的數據，據之，計算各段導體的等效電路參數，以建立等效RLC電路模型；第二部份針對台電69kV 公館-錦水線#41 鐵塔及觀音工業 區草漯-卜化線#16 鐵塔的接地電極系統，進行注入衝擊突波電流與土壤電阻率的現場試驗量測，遂根據量測結果與模擬的RLC 等效電路，作分析比較，獲得接地電極的高頻阻抗特性，作為未來建立不同地網模型的重要依據。
並列摘要
Ground electrodes are the basis of the power system grounding. When the transmission tower is struck by lightning, the lightning current then discharges through the tower. Of transmission tower, ground electrodes are necessitated to prevent from back flash of lightning to transmission conductor due to ground potential rise caused by lightning. During construction of the ground electrodes, low-frequency current is usually applied to resistance measurement of ground electrodes, which however, cannot capture the high frequency characteristics of ground electrodes under the striking of high-frequency lightning. It is therefore necessary to study the high frequency impedance of transmission tower. Lightning characteristics of power system is mainly simulated with ATP Draw, where ground electrodes have to be presented into equivalent RLC circuit model for analysis. However, the estimation of RLC circuit parameters relies on engineering experience. This thesis is divided into two parts. The first part uses parameter estimation method with CDEGS (Current Distribution Electromagnetic Fields, Grounding and Soil Structure Analysis) to simulate the frequency impact of surge current injected to ground electrodes. By knowing the ground current distribution and ground potential rise in electrodes, we then calculate the parameters of RLC equivalent circuit. The second part emphasizes on the test applied to the ground electrodes of Taipower’s 69kV Kungkuan-Jin hsuei tower #41 and Kuangin Industrial Park's Tsaota-Buhua tower #16. By injecting the surge current into ground electrodes and by measuring the soil resistivity, we then evaluate the RLC circuit with the measurement results to gain the high frequency characteristic of ground electrodes, which can serve as an important basis to establish ground models of transmission tower for future studies.