Automatic post-fault analysis based on disturbance data stored in substation devices : Approach towards the preventive maintenance

Sammanfattning: This report studies the possibilities of minimizing unplanned maintenance work and improving the availability of power supply by enabling preventive maintenance in power systems, without having to make additional investments in the existing systems. This was done using information from COMTRADE files (disturbance recording files) that are created in the event of a fault in the power system. The IEC 61850 standard facilitates the process of retrieving and analyzing the disturbance files by standardizing their format and the way they are stored. By creating a software solution that automatically reads and analyses the COMTRADE files, deteriorating performance of the power system equipment can be detected and preventive maintenance suggested. The result of the project is a software solution that reads and analyses COMTRADE files in an automated way. The software identifies fault events (fault start, trip signal sent, circuit breaker open, auto-reclose command, circuit breaker closed) from the recorded signals using wavelet transform as the main method. It then calculates the times of relay and circuit breaker operations. The calculated times are compared to threshold values and warnings are generated if they exceed the thresholds.