High-frequency transient suppression in the distribution network: analysis and performance enhancement of an intelligent switch protection on-column

Abstract Adjacent feeder column switches in electrical distribution systems may malfunction or refuse to operate during fault line isolation due to the rapid propagation of fault current. This fault current increases the electrical and mechanical stress within circuit breakers (CBs), potentially causing arc re-ignition, transient disturbances, and safety hazards. To mitigate these potential problems and provide dynamic reactive power support and voltage regulation during a single-phase-to-ground (SPG) fault in a 10 kV distribution network, this work proposes integrating a parallel capacitor with the column protection switch. Along with preventive measures to be taken, the impacts of arc re-ignition duration and the mechanisms of electrical fast transient (EFT) generation on the protection performance of on-column intelligent switches are analyzed. Time- and frequency-domain analyses reveal that fault-induced EFT pulse groups generate high-frequency electromagnetic interference (EMI) during fault isolation. This interference seriously disrupts the measurement circuits in switch protection. Moreover, these disturbances are heavily influenced by the coupling inductance and distributed capacitance of the feeders. To suppress EMI and improve the response of the switch and current/voltage transformers (CTs/VTs), a strategy is proposed to increase feeder capacitance by utilizing a switched-parallel capacitor. Adding the ground capacitance considerably reduced the oscillation frequency and peak overvoltage by 15.6% and introduced a delay of 0.77%. Voltage response testing under conditions of switching-induced transients and SPG fault scenarios demonstrated that increased grounding capacitance effectively mitigates transients and enhances the signal quality. This enhancement prevents false readings and mistaken detections, improves protection selectivity, and avoids CB malfunctions, thereby ultimately ensuring system stability. MATLAB and the Alternative Transient Program—Electromagnetic Transient Program (ATP-EMTP) were employed to evaluate the effectiveness of the proposed strategy.