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.
Highlights
In the power system, the transformer is one of the most important pieces of equipment, which is of great significance for the safe operation of the whole power grid
Gas Insulated Substation (GIS) generates a very fast transient overvoltage (VFTO) signal to impact the transformer, and it conducts the research on the online detection of transformer winding deformation based on VFTO
By changing the parameters of transformer winding, an equivalent circuit can correspond to different winding deformation types and deformation degrees
Summary
The transformer is one of the most important pieces of equipment, which is of great significance for the safe operation of the whole power grid. The transformer failure may cause the whole transformer to scrap and shutdown, resulting in large-area power outage. According to incomplete statistics, winding deformation is the main cause of transformer outage and scrap [1,2]. In the long-term operation process, the transformer will be heated and aged, which will reduce the mechanical strength and the ability to withstand electric power of the winding and cause slight deformation of the transformer winding [3]. It is of great significance to detect winding deformation before serious winding deformation occurs
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