Circulating Current Control in Underground Cables with Distributed Sheath Compensation

Underground power cables, commonly laid using duct banks or cable trenches, face significant challenges due to high groundwater levels that lead to submerged manholes. This not only complicates the installation of diagnostic devices like partial discharge detectors and fault locators but also threatens cable integrity. To manage these issues, cable sheath transposition boxes and grounding boxes are connected via coaxial cables and installed above ground. However, frequent changes in road planning often necessitate relocating these boxes, causing the coaxial cable lengths to exceed the standard 10-meter limit. This results in faults, such as damaged sheath protectors and partial discharges at neighboring joints. Addressing issues like excessive sheath grounding currents and defect detection in cable sheaths is vital to extending cable life, reducing maintenance costs, and ensuring reliable operation of high-voltage cable systems. This paper proposes a Distributed Cable Sheath Compensation (DCSC) controller that aims to reduce sheath grounding currents and enhance system stability by optimizing compensation reactance.