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With the developments in power electronics and microprocessor technology, it is considered that the application areas of Electronic Power Transformers (EPTs), which are expected to replace classical power transformers in the near future, will increase. One of the most important capabilities of EPTs is the ability to perform reactive power compensation without the need for additional filter elements. In addition, EPTs can be highly robust to disturbances in grid with appropriate design and control algorithms. In this study, a threephase EGT structure consisting of input, isolation and output stages is developed in the laboratory. With EPT structure, the disturbances in the grid can be compensated in the input stage of EPT. For this reason, three phase Pulse Width Modulation (PWM) based rectifier structure is preferred in the input stage of EPT. Type- 2 Neuro-Fuzzy Controller (T2NFC) is proposed instead of the classical PI or PID controller to control this rectifier structure. The proposed controller structure is used to control both the DC link voltage and the dqaxis currents of the PWM based rectifier. Furthermore, it is aimed to improve the performance of EPT against disturbances by the proposed controller structure. The control algorithms developed for the input and output stages of EPT are provided with the dSPACE DS1104 controller card. In order to evaluate the voltage sag and swell, harmonic and reactive power compensation performances of EPT, real-time operating conditions are prepared and experimental results are obtained. [ABSTRACT FROM AUTHOR]

To overcome the deficiencies of traditional gradient-based methods and other meta-heuristic algorithms, in this study, a new meta-heuristic technique, grasshopper optimization algorithm (GOA), is proposed to use in the robust design of power system stabilizer (PSS) with fractional order proportional-integral-derivative (FOPID) controller structure. The problem of setting the FOPID type PSS parameters has been transformed into an optimization problem with a time domain based objective function and solved with GOA. The proposed approach was applied to a multi-machine power system exposed to different loading conditions and faults. The performance of the proposed GOA-based newly designed FOPID structured stabilizer (GOAFOPIDPSS) is compared with GA-, ABC- and also proposed GOA-based conventional structured stabilizers. The superiority, potential and robustness of the proposed stabilizer are confirmed through nonlinear simulation studies and some dynamic performance indices. The analysis results show that the proposed GOA-FOPIDPSS controller gives excellent damping performance to low frequency oscillations under different faults and wide operating conditions. [ABSTRACT FROM AUTHOR]

In this study, the implementation of the sliding mode control method regarding a varying sliding surface on a electromechanical fin actuation system is dealt with. First, the mathematical model of the considered control actuation system is derived and then a control system considering the sliding mode control approach is designed upon the mentioned model. In this extent, the sliding mode controllers with both constant and varying sliding surfaces are evaluated individually. For the varying sliding surface case, the variation of the surface is described by means of a time dependent first order linear function. Moreover, the ajdustment is tried to be done regarding appropriately-constructed fuzzy functions, too. For comparison purpose, a classical control system accounting the PID (proportional plus integral plus derivative) control action is also designed. At the end of the study, the responses of all the proposed control schemes are evaluated altogether. [ABSTRACT FROM AUTHOR]