Research and Application of Criteria for Unbalanced Protection of Hybrid Filter Capacitors

To detect internal component damage faults in capacitors, the hybrid filter needs to be equipped with capacitor imbalance protection as the main protection reflecting such faults. However, when capacitors experience intermittent discharge from the shell due to capacitance, traditional unbalanced protection based on power frequency fundamental waves takes too long to operate, resulting in severe equipment damage. Furthermore, the first application of hybrid filters in engineering requires urgent research on the adaptability of existing protection criteria. This article proposes a novel capacitor unbalance protection scheme and verifies the effectiveness of the criterion through simulation experiments. The protective device based on this principle has been tested by a third party and has been put into operation on site with good performance. The research results of this article have certain reference value.