Design of Solid-State on Load Tap-Changing for Transformer : Using Micro-controller

The on-load tap changing (OLTC) regulators have been widely used in various industry & power Application. They ensure a good regulation of the output voltage in presence of large variations of the input voltage with typical response time from several ms to several seconds. Earlier mechanical type of on load tap changers were into practice. But they had considerable limitations and drawbacks like arcing, high maintenance, service costs and slow reaction times. In order to overcome these limitations and drawbacks electronic (or solid-state) tap-changers were developed. The continuous growth of power semiconductor devices, such as the insulated gate bipolar transistor (IGBT), triac, thyristor, has allowed the development of fast OLTC regulators which has helped to fix other problems in the ac mains, like flicker and sags. The major idea in the solid-state-assisted tap changer is that solid-state switches with more control ability operate during the tap-changing process instead of mechanical switches which helps in reducing the arc during the tap-changing process.