Analyses of the connection mode of anti-resonance using 4 PT in the neutral non-effectively grounded system

This paper analyzes the principle of ferromagnetic resonance in the neutral non-effectively grounded power system,and points out the mechanism of several common ways of harmonic elimination,then focuses on the analysis of the principle of connecting the 4 PT to prevent the ferromagnetic resonance over-voltage.The validity of the 4 PT's connection in harmonic elimination is proved.Through the analysis of the secondary connection way of common 4 PT harmonic elimination,the paper shows their sensitivity to the abnormal situation such as single-phase grounded and PT break.It points out the advantages and disadvantages and then gives some notes to each connection mode,providing evidence for rectifications and optimizations in the future.As for the 4 PT connection,the improved connection method with high impedance of 4 PT is recommended.