A New Approach for the Failure Detection and the Self-healing Process in A Solar-based Tap Changing Transformer

In this paper, a new approach for the self-healing process of the on-load tap-changer (OLTC) is proposed. The proposed circuit detects the failed power switch and enables the system to continue operation by using a series relay to disconnect the failed switch from the circuit. When the tap is moving from one level to the other, during this time the failure detection approach checks all power switches. The detection process is based on the tap voltage measurement while all gate signals of power switches are off. If the tap voltage during this time is not less than a certain voltage value, it means one switch fails. Then, the failed switch removes from the circuit via a series relay, and the substitute TRIAC replace the failed one. This removes any possible interruption in the voltage of the load. Also, the presented method is easy to implement, cost-effective and utilizes fewer components. An EMT simulation is performed to examine the effectiveness and robustness of the proposed circuit and methods.