A Current Transformer Saturation Time Difference Method for Detecting Out Of Zone Fault Using Mathematical Morphology

For the smooth operation of the power system timely detection of fault and separation of faulty part, so that the fault current do not travel to the other areas of the system causing severe outage or damage to the system relays must operate on their designed settings. Timely recognition of fault and the exact place where fault has occurred is very important and in order to avoid problems caused by difference in differential currents due to saturation of Current Transformer (CT), which causes distorted secondary current, resulting in mal Operation of relays, which can lead to severe problems in the system or possible damage to some of the power equipment, it is necessary to detect CT Saturation and timely compensate its effects. This paper proposes an algorithm based on mathematical morphology to detect CT saturation caused by the fault in the system, and by using a time difference comparison it can detect when the fault is inside the zone of protection and the when the fault is outside the zone. This method is effective in determining CT saturation and in selecting the area of fault based on the time difference. The simulation experiment was done using PSCAD/EMTDC and MATLAB.