Introduction to Partial Discharge Measurement System

A partial discharge (PD) measurement system is a critical tool for evaluating the health and integrity of high voltage (HV) cable systems. This article delves into the principles and methods of PD measurement, with a specific focus on detecting and analyzing partial discharges under impulse and superimposed voltages. Understanding these methods enhances the reliability and safety of power transmission and distribution networks.

Challenges and Objectives

The primary challenge in PD measurement is to accurately detect partial discharges, especially during impulse voltage conditions. To address this, a controlled experimental setup was employed to introduce an artificial defect into the cable joint, enabling the creation of conditions under which partial discharges can occur. This method then subjects the HV cable system to alternating current (AC) impulse and superimposed voltages to observe and measure these discharges.

Measurement Methodology

The measurement system is equipped with two high-frequency current transformers (HFCT) installed at both ends of the cable joint. These transformers are instrumental in identifying and differentiating PD signals from transient disturbances. Additionally, transient voltage suppressors and spark gaps are utilized to protect the measuring equipment, ensuring its longevity and accuracy in detecting PD. Medium-range bandpass filters are applied to filter out transient disturbances and enhance the possibility of detecting PD during impulse conditions.

Data Post-Processing

During the data post-processing phase, PD signals are separated from transient disturbances through pulse polarity analysis. This process further enhances the reliability of the detected PD events by filtering out noise and irrelevant data. The developed system differentiates the detection of so-called main discharges and reverse discharges, each occurring during the rise and tail time of the superimposed impulse, respectively.

Experimental Results and Analysis

The measurement results obtained through this system significantly demonstrate its effectiveness in investigating the effects of voltage transients on an HV cable system in a laboratory setting. The system's ability to accurately detect and analyze partial discharges, even under complex impulse and superimposed voltage conditions, underscores its importance in ensuring the safety and reliability of high voltage cable systems.

Conclusion

In summary, the partial discharge measurement system plays a pivotal role in the assessment and maintenance of HV cable systems. By enabling the detection and analysis of partial discharges under impulse conditions, this technology enhances the reliability and safety of power transmission and distribution networks. The developed methodology and experimental setup provide a solid foundation for further research and practical application in the field of electrical engineering and power systems.

Keywords

Partial discharge, impulse voltage, HFCT, HV cable system