Impact of QA/QC on the Successful Commissioning of Long 380 kV XLPE

摘要

To strengthen the Dutch EHV transmission system, TenneT TSO B.V. has recently completed a mixed 380 kV transmission system. About 130 km single phase XLPE cable was installed, including 132 joints and 24 cable terminations. Unlike many underground cable connections, the cable circuits form an important connection within the multi-ring structured Dutch transmission network, resulting in high demands regarding reliability and capacity. Extra attention to the quality assurance and quality control (QA/QC) procedures was inevitable to ensure the required reliability of the cable systems.From the start of the project onwards, QA/QC measures were focused on. This led first of all to specific requirements in the definition phases of the project and to attention to the manufacturing and related testing phases in the project. Given the large number of accessories, specific choices were made, and given the result of initial sample tests, a statistical analysis was made towards the reliability of the cable accessories. This resulted in a sufficiently proven reliability of all materials for the project.A second series of QA/QC works was related to the installation of the cable system. Risks were identified and lead to the introduction of risk based quality control into the project. As a result, a set of dedicated risk mitigation plans were defined and implemented in the project.Finally, the system has been completed and has successfully passed the SAT (374 kV for 60 minutes) with online partial discharge measurements on all accessories. No irregularities in the quality of the finalized large sized 380 kV cable systems were indicated.