Inductive Interference Assessment from 230 kV Submarine and Underground Cable Systems: A Case Study in Southern Thailand

Since the surrounding area contains existing medium and high voltage, both offshore and onshore transmission lines operated by neighbouring utility systems, as well as a gas pipeline owned by another utility operator, it was necessary to assess potential safety risks, not only to the natural environment, but also to nearby infrastructure, to ensure that the planned transmission system will not pose any threat.

To accurately model the system and ensure that all parameters are correct, coordination was carried out with relevant third-party utilities to gather essential information, including conductor and pipeline specifications, exact locations and depths of each line route, substation drawings, and other technical details.

A software tool was used for the study, with technical support provided when required. The induced voltage assessment followed sheath-bonding and coupling practices consistent with

IEEE 575, while grounding assumptions referenced IEEE 80. The assessment covered induced voltage and current on nearby infrastructure, particularly the gas pipeline near the cable route, and compared electrical conditions on existing transmission lines with and without the new 230 kV circuit to determine any noticeable impact. The results confirmed that the new 230 kV cable system exerts minimal electromagnetic influence on nearby infrastructure. Induced voltages and currents on adjacent circuits were negligible, while values on the gas pipeline remained well within internationally accepted safety limits. Both the normal and fault analysis confirm that all calculated values remain well within the requirement from the pipeline utility. Magnetic field levels under normal operating conditions were also calculated for reference.
Overall, the planned system does not introduce any adverse effects on the surrounding infrastructure.