Inter-turn fault modeling of a variable speed pm wind generator using physics-based approach

Model-based approaches to the inter-turn fault diagnosis of electrical machinery cover three main categories: fault modeling, feature extraction, and classification. In this paper, the modeling of a PM generator with the internal permanent short circuit fault under speed variation is presented. For this purpose, the geometrical dimensions, winding arrangement, material, and phase resistance of a typical PM machine are designed. The designed values are used to create a physics-based phase variable model of the PM generator. The Physics-based phase variable model of the machine is created using the back emf´s and inductances obtained from a nonlinear transient FE analysis of the machine. The permanent fault is modeled as a parallel resistance with some turns in one of the phases. The physics-based model of the machine includes information about the fault location and the number of turns which are shorted. The Physics- based phase variable generator model is then placed in a network consisting of a rectifier, dc bus, DC/AC converter, and a balanced AC load. The effects of variation in the number of shorted-turns, fault resistance, and speed on the voltages terminals of generator were studied. The simulated results show promising information for the identification of inter-turn faults and their classification for the diagnostic studies of a variable speed wind PM machine.