Transformer Inrush Current Moderation Through Series Voltage Compensation

Voltage sag is 92% of industrial power system installations, leading to reduced system efficiency and significant commercial and economic losses for manufacturers. Voltage sag compensators, which generally include transformer- coupled voltage-source inverters, are successful solutions against such sags. Transformers installed at critical load provide electrical isolation but are subjected to abnormal voltages & DC flux voltages offset during voltage sag. When the compensators replace the load voltage, the transformer's flux linkages can contact magnetic saturation, resulting in severe inrush currents. These inrush currents have the potential to trigger the compensator’s overcurrent protection, interrupt the compensation process, and lead to load disruption. This paper proposes a voltage sag–based mitigation strategy to reduce transformer inrush current, compensators, ensuring reliable compensation and uninterrupted power supply to critical loads.