Signal Detection for Optical AC and DC Voltage Sensors Based on Pockels Effect

A new signal detection technology is presented to improve the stability and robustness of the optical voltage sensors (OVSs) based on Pockels effect for the measurement of ac and dc voltages. The closed-loop error of the OVS is a weak and nonlinear signal vulnerable to unavoidable noise. Simultaneously, the nonlinearity and noise in physical components of OVSs are the major causes of performance deterioration of system in practical high-voltage applications. We design a signal detection hardware that can precisely extract nonlinear closed-loop error and be applicable for the measurement of ac and dc voltages. Based on the signal detection hardware, we analyze the dynamic model of closed-loop OVSs considering the effects of nonlinearity, noise, and time-delay. The control scheme of OVS is proved to obtain exponential stability with a desired attenuation level of noise. The experimental results show that the OVS has a wide bandwidth up to 24.5 kHz, the maximum step voltage 19.5 kV, the accuracy of ac and dc voltage within 0.2% and 0.5%, respectively. The experimental results validate the effectiveness and usefulness of our proposed detection method.