Study on fiber optic voltage transformer and its harmonic measurement error correction method

Abstract As an insulating material, optical fiber exhibits significant advantages in measuring both electrical and non-electrical quantities in high-voltage power systems, owing to its small volume, light weight, and immunity to electromagnetic interference. Thus, by innovatively combining the increasingly mature fiber optic current sensing (FOCT) and capacitive voltage division technologies, an optical fiber voltage measurement scheme (FOCT-OVT) is proposed, which mitigates the inherent limitations of conventional optical voltage transformers, including inferior thermal performance, compromised vibration resistance, intricate demodulation, and a narrow dynamic range. This scheme employs a dual-solenoid FOCT to measure the minute capacitive current, thereby enabling the derivation of the primary voltage. To address the harmonic measurement error induced by multi-turn coils, a capacitor-resistor series compensation method is proposed. A 110 kV FOCT-OVT prototype is developed, and a comparative analysis of the system’s fundamental performance is performed before and after compensation. The test results indicate that the compensated FOCT-OVT, consisting of a 5000 pF high-voltage capacitor and an 8000-turn coil, achieves an accuracy of 0.2% metering class and 3P protection class specified in IEC 60044-7:2008 across the frequency range of 50–1200 Hz. Consequently, the proposed approach offers a robust solution for high-fidelity passive high-voltage sensing applications.