DC Bias And Short Circuit Fault Identificayion Of Dry-type Transformer Based On Vibration

With the vigorous development of the country’s power construction and the continuous improvement of the economic level,my country’s power generation and electricity consumption are also increasing day by day.According to research,the ratio of power generation to the required matching transformer capacity is about 1:11.Dry-type transformers are widely used in people’s daily life and work places,such as shopping malls,office buildings,and residential areas,because of their significant advantages such as high efficiency and energy saving,convenient daily maintenance,and safe and reliable performance.Dry-type transformers play a pivotal role in the daily power supply and distribution system.If the transformer works under abnormal conditions for a long time,it will cause damage to its mechanical structure and cause safety production accidents.Dry-type transformers cannot be equipped with gas protection,so it is a desirable method to feedback the operating status of the transformer through vibration information.This paper takes SCB10 1250/10/0.4 dry-type transformers as the research object,and mainly carried out the following work:1.The method and process of electromagnetic harmonic response analysis for dry-type transformers are described.A physical model including dry-type transformer windings,iron cores,brackets and clamps is established in Solid Work,and the electric field is carried out in ANSYS Workbench software.,Magnetic and structural field coupling analysis.2.Analyze and study the force of the transformer under normal working conditions of the transformer,short-circuit of the secondary winding and DC bias conditions;then import the transformer force parameters obtained from the electromagnetic field analysis into the harmonic response field for coupling analysis to study different working conditions Vibration characteristics of the lower transformer windings.The simulation results show that the vibration of the transformer windings is mainly concentrated at 100 Hz,and the amplitude of the vibration acceleration of the transformer windings is proportional to the square of the ratio of the load current to the rated current.When a short-circuit fault occurs at the outlet of the secondary winding of the transformer,the vibration acceleration of the winding will increase sharply,which may cause damage to the transformer.When the transformer works under a DC bias fault,the vibration of the winding will increase,and the acceleration amplitude of the low-frequency component and the high-frequency component will increase at the same time,and the proportion of vibration at 100 Hz will decrease.3.The vibration characteristic mode of the transformer in the fault and DC bias state is extracted,and a fault identification method based on the comprehensive judgment of the support vector machine and the voltage,current information and temperature is given.And a fault warning and diagnosis interface is established in Matlab to provide reference for actual deployment.