Enhancing medium voltage underground circuit design: Assessing limitations, thermal influence, and accurate modelling

Abstract

The research article conducted a study aimed at elucidating the limitations present in existing international standards related to the permissible quantity of medium voltage circuits that can be placed within a single trench. The study also explored important considerations for underground circuits in the context of renewable energy projects, particularly focusing on the crucial roles of capacity and load requirements in cable design. The research employed advanced finite element methods with Composition, Environmental, Structure, and Mechanism (CESM) and mathematical modeling to enhance existing procedures defined by international standards like IEC 60287, 60502, and 60228. The primary parameter of interest was the thermal influence of subterranean XLPE (cross-linked polyethylene) current capacity, considering various factors such as circuit quantities, distances, and depths. Notably, the study made several key findings, including a notable reduction in the current capacity of the underground circuits. This reduction in current capacity was found to vary, ranging from 100 % to 25.75 %. The reduction was attributed to factors such as native soil conditions, circuit separation. The findings furnish valuable insights into the challenges pertinent to medium voltage underground circuit design. Moreover, the paper establishes the accuracy of the proposed process, achieving a precision of 99.4850 ± 0.5150 % for 240 mm2 and 99.3698 ± 0.6301 % for 630 mm2.

Keywords

• Failure analysis
• Finite element
• Underground cable