Sharif Digital Repository

The increasing application of non-linear loads in power system causes additional losses in transformers resulting in premature damage. Manufactures and users of transformers realise the importance of this phenomenon and it is vital to adopt a procedure to prevent it thereby enhancing the reliability of power system. To achieve this, the most common method is derating of transformers. This paper intends to review derating of transformers under nonsinusoidal operation, for which all available approaches are classified into four major methods including IEEE recommended, analytical, experimental and finite elements based method. For each method, the fundamental theory, significant factors... 

We present a nonlinear geometric approach to fault detection and isolation (FDI) in a grid-connected inverter system. Open-switch faults in inverter power transistors together with faults in grid voltages and source current sensors are detected and isolated in the presence of disturbance. The detection process is based on dynamic model of an inverter, including a dc-bus capacitor and an output $RL$ filter. The proposed FDI system does not rely on balanced or zero-sum conditions in the grid point and is functional under nonsinusoidal voltages and currents. © 1993-2012 IEEE  

We present a nonlinear geometric approach to fault detection and isolation (FDI) in a grid-connected inverter system. Open-switch faults in inverter power transistors together with faults in grid voltages and source current sensors are detected and isolated in the presence of disturbance. The detection process is based on dynamic model of an inverter, including a dc-bus capacitor and an output RL filter. The proposed FDI system does not rely on balanced or zero-sum conditions in the grid point and is functional under nonsinusoidal voltages and currents. IEEE