A METHOD FOR AN EXCITATION ASYMMETRY FOR THE DISTRIBUTION TRANSFORMERS VIA HARMONICS ANALYSIS IN AC EXCITATION CURRENT WAVEFORM

摘要

pA method for detecting an excitation asymmetry for the distribution transformers via harmonic content analysis of magnetizing current has for a novelty the phase (203) which checks whether there is DC offset by using criteria that includes the first check whether the amplitude of the signal frequency components of the mentioned even harmonics is above a predefined threshold and if so then the method checks the phase difference of even harmonics in such a way that if the phase difference has a value of 0 then we have a positive value of DC offset, but if it has the value π then we have a negative value of the DC offset. In effect, the method is focused on detection of a DC component in an AC 220V distribution network and this DC component is taking on a mili volt level. The method talks about the voltage (100) from 220V AC network, also includes saturable reactor (103) that is very low regular resistance resulting in a relatively large DC current that passes through the coil and moves so quiet setpoint of B-H characteristic. So moved BH characteristic creates asymmetry in hysteresis loop and finally asymmetric hysteresis loop that makes significant gains magnetizing current harmonic components whose vapor phase tells the offset polarity (+ or -) until we sum the intensity amplitude of 2, 4, 6, and 8. harmonics mostly talk about the intensity of DC offset./p