Ferroresonance Modeling and Analysis in Underground Distribution Feeders

Nowadays, many modern electrical power systems are designed for transmission and distribution using underground systems. Such systems minimize visual impact, reduce congestion, and increase security and reliability. However, the technology utilized has increased the capacitance effect, which can lead to the system being more susceptible to the occurrence of the ferroresonance phenomenon. Ferroresonance can cause dielectric or thermal damage and consequently makes the system susceptible to faults in the electrical power equipment and installations. This paper analyzes the ferroresonance phenomenon after switching maneuvers in a real underground distribution feeder to detect possible conditions of ferroresonance. The analysis is carried out in a typical underground distribution system with distribution transformers connected in wye-grounded/wye-grounded (Ynyn), and modeled using the ATP/EMTP software.