Impact of 11kV Capacitor Bank Switching at Distribution Power Network from Power Quality Perspective

Abstract

This study investigates the consequences on the power quality of the distribution power network during several switching scenarios of shunt capacitor banks; at different phase angles, using Vacuum Interrupter Circuit Breaker (VI-CB). Real power quality measurements were recorded at the 11kV side of the main distribution power substations (132/11kV), and due to the unexpected findings, a distinct measurement method has been developed and followed for meeting the need of obtaining a real measurement of Transient Recovery Voltage (TRV) across the opening contact gap of the VI-CB; using a special power quality analyzer, resulted in capturing outstanding findings which seems to counter the scientific documentation found in the relevant literatures which mainly rely on system modeling and simulation results. Focus was also given on harmonic analysis during switching events. Furthermore, Fault Tree Analysis method, used to explain the failure modes and consequences of these power quality disturbances during capacitor bank switching. The conclusion highlights some important factors and results related to the high frequency behavior and amplitude amplifications of both current and voltage during switching events.