Dual-Electrode Sensor for AC and DC Electric Fields in Hybrid HVdc/HVac Systems

With the increasing adoption of hybrid high-voltage direct current (HVdc) and high-voltage alternating current (HVac) transmission systems, hybrid electric field has become an essential indicator of the electromagnetic environment. This article presents the design and testing of an integrated sensor that simultaneously measures both ac and dc electric fields, particularly in the context of HVac/HVdc transmission lines. The sensor operates by modulating the electric field through electrode rotation, generating dual-path signals on inner and outer electrodes. These signals are then separated and demodulated using a specialized processing circuit, providing precise measurements of ac and dc field amplitude and polarity. The sensor’s principles are validated through theoretical analysis and finite element simulations, which also optimize the electrode vanes, area ratios, and spacing. Experimental results demonstrate the sensor’s ability to effectively separate and measure hybrid electric fields within typical transmission line voltage ranges, with ac and dc sensitivities of 0.214 and 0.168 V · (kV · m⁻¹)⁻¹ , respectively. Long-term stability tests reveal fluctuations below 3.04%, highlighting the sensor’s reliability for continuous field monitoring. This work presents a novel approach for monitoring electric fields in HVdc/HVac hybrid transmission environments, offering significant potential for enhancing grid stability and system reliability.