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This paper presents a new method for modeling the steady-state behavior of the currents transmitted between the windings of a transformer subjected to an inter-turn short-circuit fault (ITSC). ITSC is one of the most frequent and most damaging faults in magnetically coupled circuits, which occur in power transformers. Coupled Electromagnetic Circuit (CEMC) Model modeling the reasoning and relationships describing the operating principle of a power transformer through the electrical and magnetic parameters defined by the self and mutual inductances that influence the voltages and currents transmitted between the transformer windings. The representation of the state variable equations of a proposed model of a three-phase multi-turn transformer in healthy mode (no fault) and in degraded mode (with inter-turn short-circuit faults of 10%, 20% and 30%) has been implemented using a program inserted in MATLAB software. The simulations illustrate the evaluation of the primary and secondary currents as well as the voltage drop across a load, and the accuracy of the state model based on the coupled circuits was validated. The results obtained can provide a basis for the design of the short circuit of the multi-turn transformer.

The work proposed in this paper concerns the study of short circuit faults in a single-phase inverter dedicated to a photovoltaic application by applying the frequency response analysis (FRA) technique on this IGBT-based inverter controlled by a 18F2550 microcontroller, a prototype inverter was designed in the laboratory to be able to apply off-line short-circuit faults using an LRC meter. The FRA technique is based on the comparison of amplitude-frequency and phase-frequency signatures of healthy cases and fault situations. The experimental results also led to the conclusion that frequency response analysis can be used as an effective tool to detect faults in power electronic devices. This method allows for efficient detection and classification of faults with ease of implementation. For fault location, the fault branch is determined according to its position relative to its healthy state.