Analysis Of Physical Characteristics And State Diagnosis Of Winding Fault In Amorphous Alloy Transformer

With the continuous acceleration of Chinese industrialization process,the demand for electric energy is increasing,the installed capacity of power system and the scale of power grid are increasing.The safe and economic operation of power grid and equipment has always been an important technical issue of concern in the industry,which directly affects the efficiency of power supply enterprises and concerns the national economy and people ’s livelihood.The state vigorously implements the ’ carbon peak,carbon neutral ’ development strategy,and reducing power grid loss has always been the top priority of power system technology and management.As an important part of the power grid,the distribution transformer is the key equipment for the distribution of electric energy,which plays a vital role in the safe operation of the distribution network.The application of amorphous alloy transformer is an important part of energy saving and emission reduction in the power grid.The amorphous alloy transformer has the excellent characteristics of low air load loss and low air load current.However,due to its special rectangular winding and core structure,the problem of unbalanced winding bearing is prominent,and the winding inter-turn short circuit fault is more likely to occur.The slight inter-turn short circuit fault is also easy to cause the chain effect,resulting in equipment damage,power supply interruption,and affecting the safe and stable operation of the distribution network.Therefore,it is urgent to analyze the multi-physical parameter variation characteristics of the amorphous alloy transformer during the single-turn slight inter-turn short-circuit fault,and to explore the sensitive state quantity for the state diagnosis of the slight inter-turn short-circuit fault of the amorphous alloy transformer,so as to detect whether the amorphous alloy transformer has a slight inter-turn short-circuit fault in real time and improve the power supply reliability of the distribution network.Firstly,based on the principle of electromagnetic-fluid-temperature multi-physical field coupling,the field-circuit coupling simulation model of amorphous alloy transformer is established in Maxwell 3D,and the electromagnetic-fluid-temperature field coupling simulation model of amorphous alloy transformer is established in Workbench.The distribution of electromagnetic field,fluid field and temperature field and the variation characteristics of each parameter under rated operating conditions of amorphous alloy transformer are simulated and analyzed.The correctness of the coupling simulation model is verified by no-load test,load test and temperature rise test,which provides theoretical guidance for the study of inter-turn short circuit fault of amorphous alloy transformer winding under different operating conditions.Secondly,based on the electromagnetic-fluid-temperature field coupling simulation model of amorphous alloy transformer,this paper compares and analyzes the different variation characteristics and different distribution laws of multi-physical fields such as electromagnetic field,fluid field and temperature field after the winding inter-turn short circuit fault occurs in the first,middle and end of the winding and the outer,middle and inner layers of the winding.The top oil temperature of the transformer is an obvious and easy to obtain state quantity,which provides a theoretical basis for the state diagnosis method of the slight inter-turn short circuit fault of the amorphous alloy transformer.Finally,starting from the sensitivity and difficulty of obtaining the fault state quantity,a state diagnosis method of amorphous alloy transformer winding fault based on the change rate of top oil temperature is proposed,and the temperature fields under different load rates and different ambient temperatures are compared and analyzed.This method can effectively diagnose the slight inter-turn short circuit fault of amorphous alloy transformer winding,prevent the further deterioration of slight inter-turn short circuit fault,and provide help for on-line monitoring,condition diagnosis and operation maintenance of amorphous alloy transformer winding insulation.