Signal processing for electro-optic voltage sensor

We present an electro-optic sensor for accurate AC voltage measurement in high voltage substations. This paper focuses on the novel signal processing method developed to retrieve the applied voltage from the sensor´s periodic optical signals. The sensor head was presented in an earlier publication. The method is capable of extracting the sensor temperature directly from the optical signals and uses this information for temperature compensation. This enables the sensor to operate with an accuracy of ±0.2% between -40 °C and +80 °C. Compared with earlier solutions, robustness has been improved as the method can now determine the intrinsic birefringence of the optical sensing element and thereby remove a fundamental source adding to the measurement error. This allows relaxing the requirements for high quality optics.