Simulation of zero sequence current transformers for protection against single-phase ground fault in medium voltage cable networks

Inhalt:
In distribution cable networks of medium voltage (in Russia 6-10 kV), the most common type of damage is single-phase ground fault (SPGF). In an unearthing system, a significant part of the SPGF has an intermittent arc character, which is accompanied by intense transients that have a significant impact on the selectivity and stability of operation, both directional and non-directional current protection against this type of damage. The most effective method for studying the dynamic modes of operation of protection devices against these types of SPGF is a simulation. One of the most difficult tasks arising in the development of simulation protection models is the modeling of zero-sequence cable current transformers. The article is devoted to the development of a simulation model of a zero-sequence electromagnetic current transformer in Simulink, which allows simulate both steady-state and transient SPGF modes with sufficient accuracy at various secondary loads, taking into account the influence of magnetic circuit saturation.