Steady-state error analysis and digital correction for capacitor voltage transformers

The residual reactance caused by frequency variation and the characters of secondary burdens are the main factors cause steady-state error of capacitor voltage transformer (CVT). In order to correct the error, the parametric model of CVT is established and the validity was confirmed by simulation and experimental data of accuracy test. A new method based on this model is proposed to correct the steady-state error for on-line monitoring. In this method, output voltage of measuring winding and burden currents of CVT are collected to determine the primary voltage. The impact of temperature change to this correction method is also studied. The presented results indicate that the errors, both in ratio and phase, can be reduced well and the accuracy of insulation measurement for other equipments can be improved.