Pusat Pengajian Kejuruteraaan Elektrik dan Elektronik - Tesis

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Browsing Pusat Pengajian Kejuruteraaan Elektrik dan Elektronik - Tesis by Author "Al Tak, Mazyed Awan Ahmed"

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    Suppression of transient overvoltage generated by switching operation in high voltage power system during shunt reactor de-energisation.
    (2025-06)
    Al Tak, Mazyed Awan Ahmed
    Shunt reactors are commonly used in high-voltage transmission systems to compensate for capacitive effects, especially in long, lightly loaded lines where the Ferranti Rise can occur. A major challenge during the de-energization of these reactors is the generation of transient overvoltages, primarily caused by current chopping. This occurs when the circuit breaker interrupts inductive current before it naturally reaches zero, leading to a sudden release of stored energy and resulting in damaging overvoltage across both the reactor and the circuit breaker. These transients directly stress the insulation of both the reactor and the circuit breaker, increasing the risk of dielectric failure and reducing overall equipment lifespan. Conventional mitigation techniques such as pre-insertion resistors, RC snubbers, and surge arresters often fall short in addressing the root cause: current chopping. To address this gap, this study proposes a novel modification to the circuit configuration by integrating a second circuit breaker with an inherent resistance. This model aims to suppress excessive transient voltages more effectively. Simulations using ATP Draw software for a 150 MVAr, 400 kV shunt reactor show promising results. The proposed model reduced overvoltage across the shunt reactor by 12% and TRV across the circuit breaker by 7% at high current levels. Under minimum current, overvoltages reached 72% and 37%, respectively. These findings demonstrate the proposed model ability to limit harmful transients during reactor switching and highlight its practical value in improving power system reliability.