Performance assessment of distance protection fed by capacitor voltage transformer with electronic ferro-resonance suppression circuit

• Recent method to damp oscillations using electronic ferro-resonance suppression circuit.
• Performance of electronic ferro-resonance suppression circuit investigated.
• Investigation done for varying SIR, loading condition and for different fault types.
• Comparative study made with existing active and passive ferro-resonance suppression circuit.

Distance relay may over-reach when the voltage information is delivered from capacitor voltage transformer (CVT) and when source to line reach impedance (SIR) is high. A technique adopted recently involves attacking the CVT transient problem from source side itself, i.e., by using electronic ferro-resonance suppression circuit (FSC), rather than allowing the transients and tackling this issue in the relay by providing adaptive zone 1 reach, providing a fixed time delay or using a narrow band pass filter which increases the total fault clearing time by the local relay. The work in this paper investigates the performance of CVT with electronic FSC for different fault, loading and SIR conditions.