摘 要

電力系統運轉過程中，當系統結構改變或遭受外力干擾之際，常會伴隨著許多不穩定的暫態現象發生，而此暫態過程將可能導致系統出現過電壓的異常情形，依其發生時之頻率區別大致可分為高、中及低頻等三種；其中開關突波與雷擊突波屬於高頻過電壓現象，電容切換易引起中頻過電壓的發生，而鐵磁共振則歸屬於低頻過電壓範圍。前述之過電壓現象，不但容易造成電力設備的絕緣破壞，也會影響系統運轉時的可靠度與穩定度，尤以鐵磁共振現象所造成的損壞較為嚴重，且常為一般運轉人員所忽略。基於此，本論文運用電磁暫態程式 (Electromagnetic Transients Program, EMTP) 完整建立電力開關場之相關模型，並以深澳發電廠更新改建後之161kV及345kV系統為案例，模擬並分析系統於操作過程中所可能產生之過電壓現象。依據模擬結果分析，系統並無鐵磁共振情形發生，且開關場加壓至系統所產生之開關突波亦不致對系統產生不良影響。本研究結果可供設計及運轉維護人員參考，以期能有效減低鐵磁共振之可能性與過高開關突波對於系統之影響。

關鍵字：鐵磁共振、開關突波、電磁暫態程式

Abstract

When the structure of power system is changed or facing external disturbances, many unstable transient phenomena may occur during the transient period. This transient process may lead to overvoltage situation and will have some impacts on the power system. Depending on the frequency of transient process, the transient phenomena can be broadly classified as high, medium and low frequency. The switching and lightning surges belong to a high-frequency overvoltage phenomenon. In contrast, capacitance switching is identified as medium frequency overvoltage, whereas the ferroresonance is a typical low-frequency overvoltage. These overvoltage phenomena will not only damage the insulation of electrical equipment but also affect the reliability and stability of system operation. Among them, the ferroresonance can incur more adverse effects to the system and is often ignored by the system operators. Therefore, this thesis first uses Electromagnetic Transients Program (EMTP) to build the complete system model of an example power switchyard, namely the rebuild Shen-Ao power plant. Then, different simulation scenarios are conducted for both 161 kV and 345 kV system of the power plant under different operation conditions to explore the possible overvoltage phenomena. Results obtained from the example system show that ferroresonance phenomenon dose not occur, and the switching surge generated when the system is energized from the switchyard will not have adverse impacts on the system. From the study, design and operation suggestions can be provided with a view to effectively reduce the possibilities of ferroresonance and unduly high switching surges before rebuilding the power plant.

Keywords: Ferroresonance, switching surge, EMTP

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