The purpose of this paper is to present a new hybrid analytical model (HAM) based on winding function theory (WFT) for electromagnetic analysis of performance of one typical unbalanced two-phase induction motor (UTPIM). Different indexes of electromagnetic modeling such as winding distribution, slotting effect, and magnetic saturation can be accurately considered by using the proposed HAM. For obtaining this new hybrid technique, WFT is reformulated for considering the magnetic saturation in addition to the influence of slotting and winding distribution. The conformal mappings (CMs) are used to accurately calculate the slotted air-gap length. The magnetic equivalent circuit (MEC) model is used to consider the magnetomotive force (MMF) drop in stator and rotor cores due to the excitation of one phase-winding.The obtained results of CMs and MEC are then utilized in reformulated WFT to calculate the inductances of respective phase-winding. Transient analysis is then done to calculate the indexes of performance such as air-gap magnetic field, phase currents, electromagnetic torque, and rotor speed by using the lookup table of inductances while considering different capacitors in auxiliary phase. In each step, the accuracy of analytical results is confirmed by comparing with corresponding results obtained from finite element method (FEM).
Partial Discharge (PD) is one of the most important factors in the gradual destruction of transformer insulation, more importantly if the problem is not resolved can cause complete insulation failure. Physical localization of the fault inside the transformers in terms of saving repair time and cost is important. In this paper, by modeling a high voltage winding of a power transformer as a single-layer disk winding with air core the localization of PD is investigated. In this configuration, winding consists of six disks. Here, by applying impulse voltage as PD signal to the beginning of each disk, the voltages are measured and saved online at the bushing and neutral ends of the winding. By using the curve fitting method, the equations of PD signals at these two ends are extracted, then by computing transfer function in Laplace domain the magnitude of this transfer function are saved as a reference diagram. We have done this for all 6 disks. When PD occurred at winding by measuring voltages at bushing and neutral ends and drawing transfer function and comparison with reference diagrams, each diagram that has minimum difference with drawn diagram is the place of PD. Finally, the proposed method is validated with a laboratory winding with six disks.
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