Analiza algoritama za kompenzaciju zasićenja strujnog transformatora

The main function of current transformers is to adapt the high values of the primary current to values suitable for the operation of relay protection devices, i.e. measuring devices. Under normal conditions, a current transformer transforms the current in a virtually permanent ratio, and practically without a phase shift, so the secondary current is actually a scaled value of the primary current. However, when a fault occurs in the power system, currents reach high values. As a result, the flux in the core of the current transformer can reach values above the knee of the magnetization characteristic, causing saturation of the current transformer. When saturation occurs, the secondary current is no longer a scaled value of the primary current, but is deformed. Deformation of the secondary current may cause malfunctioning of some relay protection devices. The development of digital relay protection has made it possible to perform software saturation compensation by applying certain algorithms, thus eliminating the negative consequences that saturation of the current transformer causes. In this paper, one of the possible approaches for compensation of saturation is analyzed, which is based on the application of an equivalent scheme and magnetization curve of the current transformer. Two typical approaches have been singled out, which have been analyzed and tested in more detail. Testing was performed in the MATLAB/Simulink.