Electric Field and Thermal Analysis of 132 kV Ceramic Oil-filled Cable Sealing Ends

This paper reports on a method combining the use of finite element simulations and external measurements to provide preliminary condition diagnosis of oil-filled cable sealing ends (CSEs) without requiring downtime. Good agreement has been obtained between the predictions from the electric field and thermal simulations and the measurements on a 132 kV oil-filled CSE. The electrostatic computation combined with electric field measurements can provide information regarding the electric field distribution inside the CSE and help in identifying potential issues with the CSE design, the materials or the cable termination process. The thermal computation combined with thermal imaging can reveal potential problems, such as high resistance connection to the busbar, and provide information regarding the cooling efficiency of the liquid dielectric. The method presented can provide the starting point for prioritizing maintenance operations on CSEs

Development of Electric Field Stress Control Devices for a 132 kV Insulating Cross-arm using Finite Element Analysis

Insulating cross-arms (ICAs) allow compaction or upgrading of transmission lines. The process of designing and verifying the performance of electric-field grading devices is reported for rigid cross-arms on a 132 kV lattice tower. For the grounded end, traditional grading devices resembling rings which follow the general shape of the insulators were designed. For the high-voltage end, an iterative process yielded a novel grading device which is a unibody piece of cast aluminium that manages the field on all four ICA members. Finite-element analysis simulations show that the electric-field magnitude at the triple junctions of the insulating members meet the design criteria of 3.5 kV/cm. Also, the field magnitude on the metallic end-fittings and electric-field grading devices is maintained below 18 kV/cm. The corona extinction test was performed on ICA assemblies showing that the grading devices can effectively control the electric field at voltages up to 132 kV since the average corona extinction voltage was 173.7 kV, well above the required value. The complete ICA assemblies were installed on an existing line in Scotland in August 2013. This paper provides a set of recommendations for use of FEA in the design of complex insulation geometries

Fibre Bragg Grating Sensors for Condition Monitoring of High-Voltage Assets: A Review

The high-voltage (HV) assets in the existing power transmission network will experience increased electrical, thermal, environmental and mechanical stresses and, therefore, robust condition monitoring is critical for power system reliability planning. Fibre Bragg grating (FBG) sensors offer a promising technology in HV applications due to their immunity to electromagnetic interference and multiplexing capability. This paper reviews the current technology readiness levels of FBG sensors for condition monitoring of transformers, transmission lines, towers, overhead insulators and power cables, with the aim of stimulating further development and deployment of fibre-based HV asset management systems. Currently, there are several reported cases of FBG sensors used for condition monitoring of HV assets in the field, proving their feasibility for long-term use in the power grid. The review shows that FBG technology is versatile and can facilitate multi-parameter measurements, which will standardise the demodulation equipment and reduce challenges with integrating different sensing technologies