Optimization of Corona Ring Design Used in UHV Composite Insulator by PSO Algorithm

The three-dimensional model for the V and I type composite insulators used in AC 1000kV single-circuit tangent power transmission tower has been established, and conducted E-field calculation in FEM software, the results show that maximum electric field strength of corona ring used in V type insulator is about 13.9% and insulator surface 29.2% higher than that of I type, thus corona ring structure should be further optimized. So PSO algorithm has been implemented, meanwhile, submodeling technique was also used to solve such large calculation amount problem due to complexity of used model which can effectively reduce calculation amount without lose of accuracy. Then the method combining FEM and PSO algorithm has been applied to corona ring structure multi-parameter optimization used in V and I type insulators, finally, maximum E-field located in surface of ring and insulator shed can meet the electric control value, and no corona discharges can be observed when corona rings were used in actual project. The method proposed in the paper can solve structure optimization problem for large field domain and multi-media complex model, meanwhile, have reference value for researching field of insulation structure optimization with PSO algorithm.

Structural Parameters Optimization of Corona Ring of Tethered Balloon-Type VLF Antenna

The antenna end of the tethered balloon-type high-power VLF communication system will be exposed to an extremely strong alternating electric field environment when it is in operation. Due to dielectric loss, an abnormal temperature rise may occur at the antenna end, which may lead to an antenna fracture in serious cases. It is an effective measure to install a corona ring at the end of the antenna to prevent such accidents. In this paper, the structural parameters of the corona ring, including ring radius, tube radius, and ring depth, are optimized based on intelligent optimization algorithm to significantly improve the electric field distribution and restrain the temperature rise to the maximum extent. The effectiveness of the optimization results is verified by simulation.

Corona and Electric Field Distribution Analysis in 400 kV Line Insulators

The performance of insulator strings in transmission lines can be improved by corona rings owing to their electric field grading property. The insulation performance of the string depends on the corona ring parameter settings. In this study, the design of a corona ring for a 400 kV non-ceramic overhead line insulator is presented. Two parameters were altered during the investigation, ring measurement (R) and ring tube breadth (r) while maintaining a constant ring height (h). Based on electric field distribution, the proposed composite insulators were compared with glass insulators. Simulation studies were performed for the insulator strings, including corona rings with different design parameters. The corona discharge and optimal configuration results were analyzed, and it was found that the electric field was lower with composite insulators.

Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

Optimisation of corona ring design for composite insulator strings

PurposeThe purpose of this paper is to propose an optimum design of a corona ring for insulator strings using optimisation techniques, which are gravitational search algorithm (GSA) and imperialist competitive algorithm (ICA).Design/methodology/approachAn insulator string model geometry with a corona ring was modelled in a finite element analysis software, and it was used to obtain the electric field distribution in the model. The design was optimised using GSA and ICA. The variables were the corona ring diameter, ring tube diameter and vertical position of the ring along the insulator string.FindingsUsing optimisation method, the minimum electric field magnitude on the insulator string with a corona ring design is lower than without using optimisation method. GSA yields better results than ICA in terms of the optimised corona ring design.Practical implicationsThe proposed methods can help in improvement of corona ring design in reducing the electric field magnitude on the energised end of insulator strings.Originality/valueA new method to design an optimum corona ring for insulator strings, which is using optimisation methods, has been developed in this work.