Examining ferroresonance phenomena in circuits with closed and open core voltage transformers

The article shows the results of examining ferroresonance phenomena in 220 kV outdoor switchgear (OS). We examined the area of hazardous ferroresonance for NKF-type voltage transformers and open core voltage transformers, and presented a mathematical model developed for 220 kV outdoor switchgear (OS). We have convincingly demonstrated the need for taking into account interphase capacitances in one bus system and different systems during examination of ferroresonance phenomena. On the basis of calculation, we have developed recommendations on the elimination of ferroresonance phenomena on the considered OS. The developed mathematical model of OS and the method of calculating interphase capacitance bus systems using a field mathematical model can be taken as a basis for evaluating the possibility of ferroresonance phenomena at OS 110-500 kV.