A novel harmonics injecting approach on over saturation suppression of DVR series injection transformer

Voltage problems can be effectively solved by series compensators coupled with series injection transformers. However, the magnetic flux in iron core of series transformer may change in a large range depending on the close angle of injecting voltage, at the same time iron core easily get over saturated. Over saturation in transformer iron core leads to produce large field inrush current and distortion on compensating voltage wave, bring about hazard to operation of transformer and inverter, also increase the possibility of relay mishandling and finally decrease reliability of power supply. This paper analyzes the over saturation mechanism of series injection transformer and presents a novel harmonics injection control approach to suppress. The validity of proposed approach is verified by calculation and simulation