Analysis of ferroresonance in 6-35 kV electric networks including dynamic model of non-linear inductivity of power transformer.

Considering that 6-35 kV distribution networks are the longest among electricity networks, one of the special aspects of increasing the reliability of electricity supply is to investigate the influence of ferroresonance on the performance of voltage transformers (VTs). Practically, one effective measure to limit the influence of ferroresonance on the performance of VTs is to give them anti-resonance properties by changing the design of the magnetic circuit. Considering that the ferroresonance mode is quasi-stationary and occurs at both fundamental frequency and subharmonics, a key role in the research is assigned to the creation of a dynamic VTs model. Mathematical models and characteristics of non-linear inductance of VTs for investigation of ferroresonance are proposed in known scientific works. However, the obtained mathematical expressions are approximate and do not have sufficient accuracy for analysis and qualitative assessment of ferroresonance in 6-35 kV power networks. Since ferroresonance, is characterized by non-linear jumping modes of saturation of the voltage transformer magnetic core, this paper proposes the application of a generalized dynamic model of non-linear inductance of VTs and more precise analytical equations for efficient analysis of ferroresonance in 6-35 kV electrical networks. [ABSTRACT FROM AUTHOR]