Intelligent Control of On-Load Tap Changing Transformer

In this paper, an intelligent on-load tap changer (OLTC) control scheme is introduced that is based on the changes of the transformer primary side voltage and current caused by the OLTC action. It is shown that the changes in the voltage and current can be used to estimate the supply system Thevenin impedance and to monitor the OLTC stability by using a simple index. The proposed method is validated by simulation on a standard test system. Different cases are studied to demonstrate the ability of the method in monitoring the OLTC stability and avoiding or mitigating the possible instabilities.