Electric field and space charge distribution measurement in transformer oil struck by impulsive high voltage

Abstract

Transformer oil is widely used in power systems because of its excellent insulation properties. The accurate measurement of electric field and space charge distribution in transformer oil under high voltage impulse has important theoretical and practical significance, but still remains challenging to date because of its low Kerr constant. In this study, the continuous electric field and space charge distribution over time between parallel-plate electrodes in high-voltage pulsed transformer oil based on the Kerr effect is directly measured using a linear array photoelectrical detector. Experimental results demonstrate the applicability and reliability of this method. This study provides a feasible approach to further study the space charge effects and breakdown mechanisms in transformer oil.

Effect of electrode materials on the space charge distribution of an Al2O3nano-modified transformer oil under impulse voltage conditions

“…The electric field distribution across the gap can be obtained by the appropriate curve fitting from the detected eight electric field values at a given time. The relative error increases as the HV duration time increases and the relative error can be controlled at a low level (under 5%) within 3 ms [22], so we chose 250 µs, 500 µs, 1000 µs, 1500 µs and 2000 µs as the fitting time points to obtain the fitting electrode field distribution between different pairs of electrodes in pure and modified oil, as shown in figure 7, in which the dashed lines indicate the theoretical uniform fields of V/l 0 (V is the instantaneous voltage and l 0 is the electrode spacing) in the case of no space charge at the different positions). It is clear from the figures that the electric field between electrodes is distorted by the injected charge from electrodes, and becomes more uniform after transformer oil is modified, which can be proved by the electric field distortion rates of both samples with aluminum electrodes for instance.…”

Effect of the electrode material on the breakdown voltage and space charge distribution of propylene carbonate under impulse voltage

“…Furthermore, the is relatively significant for its high Kerr constant. In our previous works, [10][11][12][13][14] Kerr electro-optic measurement method is applied to investigate the space charge behaviors in liquid dielectrics such as propylene carbonate and transformer oil. Based on the space charge measurement results, the physical mechanism of space charge's effect on the breakdown process of liquid dielectrics is presented.…”

Influencing factors and uncertainty analysis for Kerr electro-optic effect based electric field measurements in transformer oil under impulse voltage

“…The measurement errors were analyzed from the laser intensity fluctuation, the photodetector noise, and the external environment's vibration. The measurement error at low field strength was controlled within 5% by the multiple average method [17,18]. However, the error sources in the electric field measurement are not limited to these factors in the above research.…”

“…By incorporating this dispersion angle into the calculation, the ratio of the output light intensity to the input light intensity can be determined from equation (18),…”