A New Electronic Voltage Transformer Applicable to AMI Smart Meters

Voltage transformers (VTs) used in the distribution-level smart meters in advanced metering infrastructure (AMI) systems are mainly composed of iron cores and windings, and are insulated with epoxy resin. Therefore, they are bulky and heavy. In addition, the complex winding structure easily leads to uneven epoxy resin grouting, so partial discharge may occur between layers in VTs, which may eventually lead to explosion accidents. This study proposes a new electronic voltage transformer (EVT), whose secondary voltage output not only meets the accuracy required by the AMI smart meter but also needs to be used to provide the power required by the AMI smart meter. The new EVT is based on the principle of resistive voltage dividers. Moreover, a push-pull power amplifier is combined to realize high power output and impedance matching. Besides, the new EVT adopts a modular design. For different distribution voltage applications, the voltage measurement requirements of 380 V/114 V, 11.4 kV/114 V or 22.8 kV/114 V can be realized by changing the cascade module. The experimental results show that the new EVT for the 380 V/114 V application not only successfully drives the AMI smart meter, but also meets the Class 0.1 according to IEC standard 60044–7.