Non-Contact Voltage Monitoring of HVDC Transmission Lines Based on Electromagnetic Fields

The high-voltage direct current (HVDC) transmission network is envisioned to advance further as a supplement to AC transmission in a new era of renewable energy and smart grid development. Voltage monitoring of HVDC transmission lines is critical for evaluating the power quality in power delivery and realizing the stability control of the power system. Unfortunately, the traditional potential transformers can only work with AC voltage while the other existing voltage sensors (e.g., Hall-effect voltage sensors, and optical-fiber voltage sensors) are still not practical for large-scale deployment for monitoring the HVDC transmission lines, owing to the fact that they are either invasive or expensive. In this paper, a non-contact electric-coupling-based voltage sensing with the assistance of magnetic-field sensing for monitoring the voltages of HVDC transmission lines is proposed. The voltages of HVDC transmission lines can be reconstructed from measuring the induced voltage of induction bars, and their correlation coefficients are attained by the magnetic sensing with an optimization program which determines their relative spatial positions. The sensitivity and stability of the proposed platform, and the corona effect of the HVDC transmission lines are discussed. The performance of the proposed sensing technique was investigated by simulation on a ±100 kV HVDC transmission line system, and was further experimentally validated on a scaled HVDC transmission-line testbed in the lab. This sensing technique can be implemented at low cost by adopting copper induction bars and magnetoresistive sensors. Considering its non-contact nature and cost-effectiveness, this technique is suitable for a large-scale deployment over HVDC transmission networks for wide-area monitoring.