Study on Non Contact Automatic on-Load Voltage Regulating Distributing Transformer Based on Solid State Relay

Automatic on-load voltage regulation of transformer is an effective method to stabilize load voltage. Mechanic contact tap changing switch is not adequate for distributing transformer because of its high cost and low capability. The paper presents the structure and automatic on-load voltage regulating principle of distributing transformer, which employs solid state relay as non contact automatic on-load voltage regulating tap changing switch. The generation mechanism and limiting measure of circular current that is occurred in the process of switching tap joint and the harmonic suppressing method are also introduced. By theoretical analysis and experimental verification, it is concluded that it has different occurring process of circular current when voltage is regulated to higher or lower value. And it is proved that the application of power electronic component in on-load voltage regulation can not generate harmonic. The sample has run for 3 months in power network. It achieves good result. And it can meet the demand for system running