Research on Power Failure Troubleshooting of Valve Cooling System in ± 800 kV Converter Station

This study investigates the cause of power failure in the pole I valve cooling system during the initial charging of the pole II converter transformer. Through systematic analysis and testing of power supply anomalies—including under-voltage, over-voltage, three-phase imbalance, and phase loss—the frequent false alarms and abnormal tripping of the main circulation pump were successfully resolved. The experimental results confirm that three-phase imbalance in the power supply directly triggers the alarm function of the valve cooling system's power monitoring relay. To mitigate false alarms while maintaining operational reliability, it is recommended to disable the three-phase imbalance monitoring alarm in the valve cooling system's power monitoring relay, provided that the system's performance remains unaffected.