Development of Multifunctional Adaptive Resonance Neutral Grounding Device

摘要

The need to shift medium voltage networks to operate in the resonance neutral grounding mode is prescribed by the Electrical Installations Code (PUE). Up to now, stepwise controlled arc suppression apparatuses have been used as the main device for compensating a capacitive ground fault current, a solution that cannot be regarded as the optimal one. The main types of arc suppression coils are considered, and their advantages and drawbacks are analyzed. To achieve a better quality of transients and to eliminate the main emergency consequences of single-phase faults, a device for controlling the active and reactive currents in the zero sequence circuit is proposed. The use of capacitor and resistor units connected in parallel with the inductance and controlled by means of a microcontroller opens the possibility to comprehensively settle matters concerned with fault current compensation, limitation of arc and ferroresonance overvoltages, and the improvement of ground fault protection selectivity. The results from the modeling of transients and magnetic fields, and from flux linkage calculations carried out using the Comsol Multiphysics computer program are presented.