Power Line Corona Rings Optimization

Innovative silicon insulators for high power transmission lines have been designed with ANSYS. Our customer wanted to design insulators with lower electrical fields than usually available in the market by optimizing the geometrical shape of the conducting corona rings. The entire design and optimization process was done in ANSYS Workbench by means of a thermal-electric analogy, while a parametric model was used for the geometric optimization. The customer could benefit from an automated workflow in ANSYS Workbench and know-how transfer for the optimization process. A new product line with significant competitive advantage was designed.

Power Line Corona Rings Optimization

Task

Our customer Pfisterer Sefag develops and manufactures insulators and fittings for worldwide use in power supply networks. In the design process of new silicon insulators for high power transmission lines, achieving a low enough electric field on the insulator surface is crucial in order to avoid damage due to corona discharges. Following a non-standard request from a customer who wanted to guarantee a lower electrical field than usually accepted, an optimization of the geometrical dimensions of conducting corona rings placed at the end of the insulator was required.

Solution

An electrostatic assumption was used with adapted maximum voltages. Since Electrostatic analyses are not included in the Mechanical module of Workbench, a 3D thermal static analysis was used with adapted units and material properties in order to calculate the electric field in the air and in the structure. The geometrical dimensions of the corona rings were parameterized and an iterative optimization procedure allowed a decrease of the maximum electric field value to a satisfying level.

Power Line Corona Rings Optimization
Electric field in the air surrounding the insulators and power line. The complete model included a total of 179 silicon shields for the two insulators

Customer Benefit

Following this study our customer has achieved:

  1. A useful design to start experimental validation and production without extensive iterative prototyping.
  2. Increased knowledge about the influence of geometrical parameters on the electric field
  3. A private training based on this consulting work with a knowledge transfer that will allow engineers at Pfisterer Sefag to perform similar analyses themselves on future new designs using the intuitive Workbench Mechanical interface.
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CADFEM (Suisse) AG

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