334 / 2022-03-15 15:44:19

Study on the development characteristics of partial discharge under the actual operating voltage of converter transformer

Harmonics,Converter transformer,Partial discharge,Actual operating voltage

Purpose/Aim

As the most critical equipment in the high voltage direct current (HVDC) system, the state of the converter transformer directly affects the safe operation of the entire HVDC system,. Compared with the traditional AC transformer, the converter transformer is subjected to complex AC voltage, AC-DC composite voltage and harmonics during operation, so the local insulation defects are more easily excited. Partial Discharge (PD) is non-penetrating discharge that occurs within the equipment insulation, which is the main manifestation of insulation failure at an early stage. Carrying out research on the development characteristics of partial discharge in converter transformer is of great significance to enhance the capability of monitoring and warning of the internal discharge faults in converter transformer, which can guarantee the safe and reliable operation of converter transformer.

Experimental/Modeling methods

In this study, an AC transformer and a DC high-voltage source were used to generate the AC-DC composite voltage, and an arbitrary waveform generator and signal amplifier were used to generate the actual operating voltage of converter transformer. A commercial PD detection equipment called PD check and dissolved gas analysis (DGA) were used to detect the partial discharge.

Results/discussion

The analysis of the experimental data shows that the DC component of the AC-DC composite voltage produces a certain degree of suppression effect on the discharge, which is consistent with the existing studies. At the same time, the harmonics contained in the actual operating voltage can affect the development characteristics of the discharge and gas production to some extent.

Conclusions

This study will obtain the discharge and gas generation development characteristics of the converter transformer at the actual operating voltage and will obtain the difference between the discharge development characteristics at the actual operating voltage and the AC-DC composite voltage.