Power Consumption Mode Investigation of a Transformer with Asymmetric Load under the Condition of Active Parts Temperature Change

Nonlinear load causes leakage of non-sinusoidal currents and voltages in the transformer, that carrying a spectrum of higher harmonics violate the thermal balance of the transformer, creating zones of high heating, disrupt the circulation of cooling around the active parts of the transformer and accelerate the aging of insulating materials. The paper presents a study of a transformer with an asymmetric load under the condition of changing the temperature of the active parts. The work purpose is investigation the relationship between the influences of temperature changes of the transformer active parts on the power consumption mode with asymmetric load. The transformer equavalent circuit equations with introduction of parameters dependence on the temperature change for one of the phases are used, as well as the balance equation of the transformer power components. The equations are presented for influence of temperature change on material parameters of primary or secondary windings and the magnetization path of transformer equivalent circuit, as well as for the balance of power flow components. Experimental researches of the laboratory transformer with asymmetric loading are carried out. In the course of experimental studies it was found that the temperature has an effect on the properties of the steel of the active parts of the transformer, creating the preconditions for the unbalanced distribution of magnetic flux values, power and THD current phases, increasing the negative impact on operation and transformer service life. The obtained results can be applied in the tasks of monitoring and forecasting of anomalies during operation of the transformer in the asymmetric loading mode.