Calculation and error analysis of the electric field for a quasi-reciprocal optical voltage sensor

The optical sensing element in transverse modulation configuration utilizing the Bi₄Ge₃O₁₂(BGO) crystal was designed for a novel optical voltage sensor with quasi-reciprocal reflective optical circuit. The numerical calculation of electric field was performed using the finite element analysis based software ANSYS and the distributions of both electric field and electric potential were obtained. The influences of the non-uniformity and disturbances of electric field on the accuracy were also analyzed. The simulated results show that the maximal voltage that can be measured is not less than 15 kV at the standard temperature and pressure for the designed sensing element. The integral results of the electric field along different paths are different due to its non-uniformity, which affects the stability and accuracy of the voltage sensor. It can not be ignored for the voltage sensor with the requirement of accuracy 2‰ that the maximal relative measurement error is up to 1.2‰ caused by the disturbances of electric field with the measured voltage from 0 to 5 kV.