Performance study of a DC electronic voltage transformer with passive temperature error correction capability

Purpose This study aims to address the temperature-dependent error of the primary voltage divider (PVD) in direct current electronic voltage transformers (DC-EVT). Taking full advantage of the superior properties of optical fiber sensors such as passivity, light weight and excellent insulation, a high-resolution polarization-maintaining fiber temperature sensor (PMF-TS) is designed and embedded inside the composite insulator. Design/methodology/approach A novel DC-EVT is proposed, whose PVD features an equipotential shielding structure integrated with auxiliary voltage-dividing resistors. The secondary voltage-dividing network, constructed using multiple parallel resistor–capacitor circuits, achieves relative isolation among multiple remote terminal units, thereby enhancing system reliability. A novel optical configuration of PMF-TS with laser power delivery capability is designed, which acquires the temperature of the PVD while supplying power to the remote terminal unit, followed by temperature error correction using polynomial fitting. A 500-kV DC-EVT prototype is fabricated, and comprehensive tests are conducted to characterize its accuracy, step response and temperature performances. Findings Test results demonstrate that within the voltage range of 0.1 UR (28.87 kV) to 1.5 UR (433 kV), the ratio error (RE) fluctuates between 0.02% and 0.13%. The step response time is approximately 190 µs, while after temperature correction, the RE fluctuation is narrowed to the range of −0.05% to 0.08% over the ambient temperature span of −40°C to 70°C. The overall performance of the prototype meets the error limit requirements specified in the GB/T 20,840.15–2022. Originality/value These results verify that the prototype offers a technically feasible solution for high-voltage DC voltage measurement applications.