Identification method based on correlation analysis for SPTG fault in MMC-MVDC system

Abstract

Due to the labyrinthine topology of the MMC-MVDC system, identification of the faulty feeder especially for a single-pole-to-ground (SPTG) fault is a challenging task. Based on the characteristics analysis of capacitance charge–discharge, this article obtains the typical characteristics of the faulty feeder. To improve the sensitivity, the characteristic frequency band of capacitance current is extracted by S-transform which has excellent time–frequency resolution. According to the analysis, S-transform characteristic frequency band (STCFB) of positive and negative differential current of faulty feeder is negatively correlated while the healthy feeders are positively correlated. To distinguish the faulty feeder, an identification method based on Pearson correlation coefficient (PCC) is constructed. In terms of the energy difference between the positive and negative differential current, the faulty pole can be verified. Finally, a typical radial flexible DC distribution grid model is constructed in PSCAD, and the simulation results confirm the reliability and sensitivity of the identification method.

Keywords

• power distribution faults
• power grids
• earthing
• fault diagnosis
• power transmission faults
• time-frequency analysis
• DC power transmission
• voltage-source convertors
• healthy feeders
• faulty feeder
• identification method
• Pearson correlation coefficient
• faulty pole
• correlation analysis
• SPTG fault
• MMC-MVDC system
• capacitance current
• time–frequency resolution
• capacitance charge–discharge characteristics analysis
• single-pole-to-ground fault
• S-transform characteristic frequency band
• STCFB