Fine Voltage Control Using Oltc by Static Tap Change Mechanism

In this paper, a novel model of fully electronic on load semiconductor tap changer for power transformer has been proposed. With high power semiconductor devices, problems associated with conventional mechanical on load tap changers which includes excessive conduction losses and arcing in the diverter switch have been properly rectified. In this work Simulink model was designed with GTOs as switching devices embedded in taps. Step change of voltage is achieved changing taps by switching GTOs and fine voltage with error less than ±0.1% is obtained by sequential firing control between GTOs in the system, which is not possible in conventional automatic OLTC control system.