Analysis of induced voltage on the sheath in multi-circuit systems within renewable energy parks

Abstract

Renewable energy parks rely on underground cables arranged in trefoil formations to connect to the substation. However, challenges arise due to high soil thermal resistivity, which can limit cable capacity. Increasing the number of circuits in a trench exacerbates this issue, leading to the cables transmitting the rating current at a temperature higher than the manufacturer’s recommended, and in this way, the cable lifespan is reduced. In order to address these challenges, the cross-bonding method can be applied to mitigate joule losses by balancing the induced voltage on the cable sheath. While traditionally used in high-voltage systems, cross-bonding has found widespread application in medium-voltage environments, including wind and solar parks. This paper investigates the impact of increasing the number of circuits within a trench on induced voltage variations across the cable sheaths. This analysis employs up to seven circuits in a trefoil configuration within the trench. Additionally, precise formulations are used to calculate the earth-return impedance of cables. The results reveal that while augmenting the number of circuits improves the induced voltage performance, it adversely affects ampacity. These findings provide valuable insights for improving electrical design practices in wind parks and similar.