| Summary: | 碩士 === 逢甲大學 === 電機工程學系 === 105 === To reduce the probability of voltage collapse in transmission system, this thesis presents a voltage stability protection and control scheme. With the advent of phasor measurement units (PMUs), the online monitoring of voltage stability has become a possibility. First, this thesis developed an admittance-based voltage stability index based on the impedance match theory. By using the recursive least square method, Thevenin equivalent parameters can be determined in real-time for monitoring of power system voltage stability. Lastly, this thesis presents a two-stage method for enhancing voltage stability. In the first stage, an index is used for voltage stability monitoring. In the second stage, the flexible AC transmission system is used as the control strategy. When the power grid shows the risk to voltage collapse, the control strategy will be initiated immediately to improve system voltage level, and steer the power system away from the point which is prone to voltage collapse. Since voltage stability is affected by the load characteristics, the composite constant impedance, constant current, and constant power load model is used in this study. An extensive simulation studies on the IEEE 9-bus system, IEEE 14-bus system and IEEE 39-bus system test system is carried out to demonstrate the effectiveness of the proposed method.
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