| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 96 === 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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