Design of optical voltage sensor based on electric field regulation and rotating isomerism electrode

Temperature, stress birefringence and low frequency vibration have a negative impact on the long-term operation instability of optical voltage sensors (OVS), resulting in large random and fluctuate errors in the output signal. In order to suppress the error, this paper developed a method based on electrical field modulation with high-speed rotating isomerism electrodes and the digital lock-in amplifier technology. This method can shift the frequency band of the measured signal to $2\text{kHz}$, avoiding the low-frequency $(< 50\text{Hz})$ interference from temperature drift, stress birefringence and vibration. The waveform of modulated signal is studied by coupling wave theory and finite element simulation method. And the Simulink results show that digital lock-in technology can suppress the large random interference.

I. Introduction

Optical voltage sensors (OVS) based on Pockels electro-optic effect have the characteristics of compact size, good insulation performance and high measurement accuracy. Therefore, it is very suitable for smart grid requirements and its development prospect is very considerable [1]–[2]. However, due to the poor long-term stability, OVS is deployed only in non-critical applications for smart substations. Factors such as temperature, stress birefringence and aging are generally considered as the main reasons affecting the operational reliability of OVS, which seriously hinder its practical application and industrialization process.