Research On Vibration Characteristics Suppression And Signal Detection Of Amorphous Metal Dry-Type Transformer Core

The most outstanding advantage of the amorphous metal distribution transformer(AMDT)is its excellent energy saving characteristic,and the no-load loss and no-load current of the AMDT are only 25% and 20% of that of the conventional silicon-steel transformer.Therefore,it has broader application potential in the power industry.However,since the magnetostriction rate of amorphous alloy material is higher than that of silicon steel sheet,and it is extremely sensitive to stress,the high noise generated by the operation of amorphous alloy transformer has a great negative impact on the resident production and life.The core vibration caused by magnetostriction effect is the main source of the transformer noise,but few literatures on the vibration characteristic of the amorphous alloy core and vibration suppression measurements are reported.Thus,exploring the amorphous alloy core vibration characteristics has positive academic and application value for the development of low noise and environment friendly AMDT.In this thesis,a SCBH15-200/10 AMDT core was chosen as the research object,the finite element analysis(FEA)simulation,vibration characteristics,vibration suppression and noise reduction,and signal detection of the amorphous alloy core were studied by means of simulation analysis and experimental research.The main content of this paper are as follows:(1)The core model of amorphous alloy dry-type transformer was established,and the magnetic flux density and modal analysis of the core were calculated by FEA software according to electromagnetics and dynamics principle,and the results can provide a basis for the arrangement of the measuring points for the core vibration experiment.The simulation results of the main magnetic field of single-phase core and three-phase core indicate that the magnetic flux density at the upper yoke and the inner chamfer is higher.The natural frequencies and modal modes of the core were calculated by applying fixed constraints to the lower yoke,and the first two modes indicate that the vibration trend on the upper yoke core is most obvious.(2)The vibration testing platform of the AMDT core was built,and vibration sensors were arranged in the areas where the magnetic flux density of the AMDT core is high,so as to obtain the time domain and frequency domain waveforms after FFT of the core vibration signal.The results show that the fundamental frequency of the amorphous alloy core is 100 Hz,and the vibration amplitude is the largest when the frequency is 200 Hz.By collecting the vibration signals of the AMDT core at different positions,it is found that the central part of the upper yoke is the area with the largest vibration amplitude.(3)Based on the energy suppression of the maximum vibration point,the measurement of the reasonable control of the clamping force on the upper yoke was adapted to restrain the vibration of the core caused by magnetostriction,the vibration suppression feasibility was verified from the angle of vibration amplitude and sound pressure level.The influence of insulating tie band binding on the vibration of the yoke was explored.With the increasing of the stress,the vibration amplitude of the core decreases first,and then it increases.When the stress of 100 N is applied to the upper yoke,the vibration sound pressure level of the AMDT core is the lowest.(4)The wavelet packet transform(WPT)is used to analyze the vibration signal of amorphous alloy core in the time-frequency domain,and the vibration suppression effect of applying stress was verified according to the energy feature values of the core vibration.The time-domain vibration signals of the AMDT core were decomposed and reconstructed by the three-layer WPT to extract the energy feature values of each frequency component.The energy feature values of normal operation and different compressive forces were compared and analyzed.The suppression effect of proper compression stress on the core vibration was verified,and it can provide a reference for the detection of the operating stress degree of the AMDT core.