Modeling and stator Inter-Turn short circuit fault detection for saturable salient pole synchronous machine by a non-linear magnetic equivalent circuit approach

This paper presents a novel and adequate model for healthy and faulty salient pole synchronous machines with and without interturn short circuit fault. The model is presented for a machine with arbitrary pole numbers, arbitrary damper bars, and stator slot numbers. The magnetic equivalent circuit with nonlinear elements is used for modeling, and numerical techniques based on Newton-Raphson method have been approved for solving of nonlinear equations. Because the design of electric machines is based on the knee point of a B-H curve, consideration of saturation effect is mandatory for adequate studying. Because of the saturation effect, there are some nonlinear algebraic magnetic equations, which should be solved simultaneously with differential equations. Trapezoidal technique is used for differential equations converting to algebraic type, and Newton-Raphson method is used for a nonlinear set equation solving. Stator current signature analysis is used for stator interturn short circuit fault detection. Finally, obtained results by finite element method are used to verify the effectiveness of the proposed modeling method. The proposed approach for magnetic equations based on nodal potential and reluctance mesh model equations is one of the paper novelties for the salient pole synchronous machine modeling in both healthy and faulty cases. This dynamic modeling method has less complexity compared to finite element method and pure nodal potential approaches. Solving the electric and magnetic equations by a single set of equations is the main advantage of the presented method, which has been addressed for a salient pole synchronous machine for the first time. Another advantage of the proposed study is the capability of modeling the healthy and faulty machine with interturn fault by a single model.