Abstract
In order to simplify the research method of the spatial magnetic field distribution (SMFD) of dry air-core reactors (DARs) in the case of inter-turn short circuit fault, the concept of simplified scaling model was put forward, and the optimal simplified scaling model for different inter-turn short circuit fault was calculated by using the least square method. Firstly, in order to simplify the calculation, 7 typical directions describing the SMFD of DARs were determined based on the similarity degree of magnetic induction intensity in each direction. Then, the simplified scaling model parameters corresponding to different short circuit positions and degrees were studied, and the variation rule was described by using the method of fitting function. Finally, the original model and the simplified scaling model of the DARs in the case of inter-turn short circuit were established respectively in the laboratory. The results show that the optimal structure relative height obtained by experiment is 30% and 20% respectively, which is the closest to the parameters obtained by computer simulation, i.e.,28% and 20.3%.
Highlights
Dry-type Air-core Reactors(DARs) are important power equipment in power system, with the role of compensating reactive power, limiting short circuit current and filtering high harmonic [1,2,3,4,5]
Han et al [22] built accurate simplified three-loop scaling model by optimizing the structural parameters, which made the spatial magnetic field distribution (SMFD) along the typical directions be more similar to the original dry air-core reactors (DARs). These results show that the simplified scale model can be used to study the SMFD of the DARs with inter turn short circuit fault
For different inter-turn short circuit faults, the SMFD under this condition can be equivalent only by adjusting the position of the coils in the simplified scaling model, which greatly reduces the time spent in the experimental research process compared with the scaling model
Summary
Dry-type Air-core Reactors(DARs) are important power equipment in power system, with the role of compensating reactive power, limiting short circuit current and filtering high harmonic [1,2,3,4,5]. For different inter-turn short circuit faults, the SMFD under this condition can be equivalent only by adjusting the position of the coils in the simplified scaling model, which greatly reduces the time spent in the experimental research process compared with the scaling model. When the number of coils in the simplified scaling model is too small to reflect the geometry of the DARs, the equivalent effect will be reduced [14] This is due to the fact that the original model was a tightly wound solenoid, with the magnetic field mainly concentrated in the axial direction, while the equivalent model had a large gap between the coils, which would lead to an increase in the radial magnetic flux leakage. Since the simulation of the SMFD in the case of inter-turn short circuit fault had higher requirements on the calculation accuracy, the fivering simplified scaling model was selected under the condition of taking the simulation time into account. For the original model, when the incoming current is I, the magnetic induction intensity of P (x,y,z) in the space can be calculated by the following formula: Bx
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