Research on On-Line Detection Method of Transformer Winding Deformation Based on VFTO

Abstract

At present, the detection of transformer winding deformation faults is carried out in an offline state, which requires the transformer to cooperate with the implementation of planned power outages, or it takes place after the sudden failure of the transformer when it is out of operation. It is difficult to obtain the status information of the windings online in time. Since the transformer will suffer very fast transient overvoltage (VFTO) impact during operation, combined with the principle of the frequency response method, an online detection method of transformer winding deformation based on VFTO is proposed. In order to study the frequency response characteristics of transformer winding under the impact of VFTO, the generation process of VFTO is simulated by simulation software, and the equivalent circuit model of transformer winding before and after deformation is established. The VFTO signal is injected into the transformer circuit model as an excitation source, and the changes of resonant frequencies of frequency response curve under different deformation types and different deformation degrees of winding are analyzed. The simulation results show that the frequency response curves of different winding deformation types are different. Different deformation degrees are simulated by increasing the radial capacitance by 4%, 13%, and 23%, series inductance by 2%, 4%, and 6%, and longitudinal capacitance by 3%, 6%, and 9%, and the change of resonance frequencies can comprehensively reflect the deformation information of winding. At the same time, the tests of different deformation types and deformation degrees of the simulated winding are carried out. The results show that with the deepening of the change degree of the simulated fault inductance value, the frequency response curve shifts to the low-frequency direction, confirming the feasibility of the online detection method of transformer winding deformation based on VFTO.

Research on the Influence of Compression and Offset of Cushion Blocks on the Axial Strength of Transformers

“…Reference [15] studied the distribution of axial forces in windings during transformer short circuits through simulation. Reference [16] proposed a transformer winding deformation online detection method based on VFTO and validated its effectiveness. Reference [17] established a nonlinear vibration model considering axial vibration of windings that deduced and calculated the winding compression force, cushion block and pressure plate compression force, and the axial bending stress of the wires.…”

Design of a Fluxgate Weak Current Sensor with Anti-Low Frequency Interference Ability

“…Compared with various voltage measurement methods, the main methods currently used for current measurement include the following: shunt resistors, current transformers, Roche coils, Hall current sensors, fluxgate current sensors, and giant magnetoresistive sensors [3,4], each of which has its own drawbacks [5,6]. Compared to other detection methods, fluxgate current sensors are one of the most accurate ways to measure current today.…”