Improvement and Simulation Analysis of Impedance Characteristics for Primary Harmonic Eliminator in 6.6 kV Power System

The neutral point of the three-phase electromagnetic voltage transformer is grounded by a primary harmonic eliminator. It is a commonly used ferromagnetic resonance prevention and control measure with obvious effects. This paper addresses the problems of the 6 kV/10 kV universal harmonic eliminator in 6.6 kV system affecting the accuracy of zero-sequence protection and the potential for transformer insulation hitting when system abnormalities. Without changing the nonlinear coefficient of the harmonic eliminator, the above problems are solved by reducing the impedance of the harmonic eliminator. Analysis and simulation results show that while good harmonic elimination effect is maintained, the heat capacity remains unchanged, which improves zero-sequence protection accuracy and voltage transformer insulation redundancy.