Contactor-less OLTC system based on dynamic model

A dynamic model of contactor-less OLTC(On-Load Tap Changer) in time domain is proposed,which adopts the Jiles-Atherton theory to treat the nonlinearity caused by the hysteresis of transformer core and takes into account the parameter mutation caused by the switching of regulating windings.The dynamic model applies TLM(Transmission Line Modeling) method to obtain the transient values in time domain,suitable for researching the on-load voltage regulation of contactor-less OLTC composed of thyristors as switches with transition resistor.The bumpless voltage regulation is realized by selecting the appropriate switching time of thyristors,i.e.the current and voltage waveforms maintain continuously and smoothly during the on-off of transition resistor and regulating winding.The dynamic model is also suitable for researching the on-load regulation without transition resistor and the transformer protection.The experiment verifies the correctness and practicability of the dynamic model.