Analyzing the Characteristics of Faults in a Transmission Line and High Voltage Capacitor Banks in a 115-kV-Power System Using Discrete Wavelet Transform

The protection of conventional high voltage capacitor banks relies on an unbalance relay. However, investigating the faults requires time and human resources. To address this issue, the characteristics of system parameters were analysed in this study by performing simulations using the power systems computer-aided design software. The simulations were modelled based on a 115-kV-system of the Electricity Generating Authority of Thailand. The case studies involved faults in the transmission line, a single capacitor bank, and a back-to-back connected capacitor bank. Additionally, the influence of other factors on the system parameters was investigated, including the varying fault phase, location, and inception angles. Moreover, the discrete wavelet transform (DWT) was applied to analyse the system parameters comprehensively. The results indicate that the characteristics of system parameters in the case of faults occurring in a transmission line are unique when compared to those in the case of faults occurring in a capacitor bank. Furthermore, the discrepancy between the system parameters in the case of faults occurring in a single capacitor bank and two capacitor banks connected in a back-to-back topology was solved by applying DWT. Therefore, the study findings can aid in improving the efficiency of power systems and ensure their protection.