Research on 1000 V/20 Hz two-stage excitation induction voltage divider

The 20 Hz low-frequency transmission technology is a new type of AC transmission technology based on fully controlled power electronic devices, which has gradually been applied in construction around the world. However, it is difficult to develop high-precision low-frequency standard transformers, resulting in a blank system for tracing the values of low-frequency transformers. Inductive voltage dividers have many advantages such as high accuracy and stability, so low-frequency voltage ratio standards are suitable for using inductive voltage dividers as the source of traceability. This article proposes the principle of two-stage excitation and develops a two-stage excitation low-frequency induction voltage divider. Based on the finite element method, a three-dimensional model was established to simulate and optimize the internal electromagnetic field and structure. Designed a closed shielded iron core structure, which has achieved good magnetic field shielding effect; In order to reduce the impact of capacitive leakage, the proportional winding adopts a coaxial cable 10 wire parallel winding method to achieve outer equipotential shielding. Based on the reference potential method, this device is calibrated for errors. The error measurement device uses a lock-in amplifier SR850. According to the error calibration results, the 10 stage transformation ratio error of the 1 kV two-stage excitation low-frequency induction voltage divider is better than 1 × 10⁻⁷.