Space Charge Distribution in a Dielectric Liquid Using an Optical Method

2013 ◽  
Vol 64 (4) ◽  
Author(s):  
Haruo Ihori ◽  
Hayato Nakao ◽  
Masaki Takemura ◽  
Mitsuru Oka ◽  
Hyeon-Gu Jeon ◽  
...  
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Charge Distribution ◽  
Electric Field Distribution ◽  
Field Vector ◽  
Original Method ◽  
Time Intervals ◽  
Space Charges ◽  
Space Charge Distribution ◽  
Liquid Dielectrics

In order to diagnose the effectiveness of electrical insulation, it is necessary to obtain information regarding the electric field distribution in insulating materials. We have investigated the measurement of electric field vector distributions in liquid dielectrics using an original method. Electric field distributions could be measured in time intervals of milli-seconds by an optical system. In this study, the electric field in a liquid containing space charges was measured, and the change in the electric field caused by the charges in the liquid was examined. Moreover, the space charge distribution in the liquid was also studied. We believe that our study can aid a better understanding of the movement of charges in liquid dielectrics.

scholarly journals Empirical Conductivity Equation for the Simulation of the Stationary Space Charge Distribution in Polymeric HVDC Cable Insulations

Energies ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 3018 ◽  
Author(s):  
Christoph Jörgens ◽  
Markus Clemens
Keyword(s):  
Electric Field ◽  
Space Charge ◽  
Charge Distribution ◽  
Euler Method ◽  
Accurate Description ◽  
Conductivity Equation ◽  
Transient Model ◽  
Space Charges ◽  
Sigmoid Functions ◽  
Conductivity Gradient

Many processes are involved in the accumulation of space charges within the insulation materials of high voltage direct current (HVDC) cables, e.g., the local electric field, a conductivity gradient inside the insulation, and the injection of charges at both electrodes. An accurate description of the time dependent charge distribution needs to include these effects. Furthermore, using an explicit Euler method for the time integration of a suitably formulated transient model, low time steps are used to resolve fast charge dynamics and to satisfy the Courant–Friedrichs–Lewy (CFL) stability condition. The long lifetime of power cables makes the use of a final stationary charge distribution necessary to assess the reliability of the cable insulations. For an accurate description of the stationary space charge and electric field distribution, an empirical conductivity equation is developed. The bulk conductivity, found in literature, is extended with two sigmoid functions to represent a conductivity gradient near the electrodes. With this extended conductivity equation, accumulated bulk space charges and hetero charges are simulated. New introduced constants to specify the sigmoid functions are determined by space charge measurements, taken from the literature. The measurements indicate accumulated hetero charges in about one quarter of the insulation thickness in the vicinity of both electrodes. The simulation results conform well to published measurements and show an improvement to previously published models, i.e., the developed model shows a good approximation to simulate the stationary bulk and hetero charge distribution.

Sign in / Sign up

Export Citation Format

Share Document