Abstract
Nowadays, more and more electrical power is being distributed to customers by underground cables rather than overhead transmission lines due to their advantage of providing better protection in inclement weather. They also have significantly reduced electromagnetic field emission because of their copper shielding. But underground cables have larger capacitance than transmission lines per unit. Thus, ferroresonance is more likely to occur in distribution systems using underground cables. Moreover, soil humidity at a depth of one meter remains 100 percent for most of the year, a factor that risks the occurrence of water tree (WT) in cables. Consequently, both ferroresonance and WT are prone to occur in underground cable systems. The objective of this paper is to determine the relationship between ferroresonance and water tree. A test system was designed to simulate and analyze ferroresonance in a cable system caused by single-phase switch and water tree. Eight scenarios of water tree were compared in the simulation. There sponses of ferroresonance are presented in this paper and two common patterns are observed from the simulation results.
Highlights
In recent decades, technology has been more and more focused on decreasing power losses in the power-delivery process, taking into account both economic and ecological conditions
The response of ferroresonance depends on many factors and conditions, which are fully discussed in previous papers, such as voltage magnitude, voltage frequency and capacitance of the system
Water tree has a significant influence on the ferroresonance phenomenon
Summary
Technology has been more and more focused on decreasing power losses in the power-delivery process, taking into account both economic and ecological conditions. Ferroresonance is a nonlinear phenomenon that can generate overvoltage, over current, and harmonic distortion, which is normally caused by single-pole switch in light loaded system. Other important papers were published later and mainly concentrated on two areas: increasing the accuracy level of transformer modeling, and studying the ferroresonance phenomenon at the whole system level [7]. We know that ferroresonance is caused by single pole switch and it highly depends on the magnitude of losses and transformer connection methods. These papers have addressed ferreresonance, none of them have focused on the influence of abnormal factors such as water tree and other types of faults.
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