Simulation based design of GIS sensors for PD measurements

In this paper an electromagnetic simulation based design and optimization of novel partial discharge (PD) sensors for Gas Insulated Switchgear (GIS) is presented. Physical modeling of a sensor development system, a suitable electromagnetic field formulation, and its numerical solution by using the well-known vector FEM approach are described in detail. The described 3-D simulation framework was applied to the sensor design and optimization. The simulation results show that the sensors sensitivity in a frequency range from 10 to 2000 MHz could be improved by approximately 10dB in average. After the simulation phase the corresponding physical prototypes were manufactured and tested. The measurements performed in a short GIS prototype agreed very closely with the corresponding simulations. Additionally, an important problem of propagation of higher order guiding modes and their influence on the interpretation of simulation results in terms of the sensor sensitivity is described and an efficient solution of this problem suggested. Furthermore, the correlation between the shape of the test setup and its influence on the wave propagation is demonstrated and examined in detail.