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The Total Harmonic Distortion (THD) value is an important metric used to evaluate the performance of various devices and systems in electrical systems. A low THD value is expected for optimal performance. In this study, the THD value of the output voltage of a cascaded H-bridge multi-level inverter (CHB-MLI) was optimized by using a newly developed Dwarf Mongoose Optimization (DMO) algorithm. The performance of the adapted DMO algorithm has been tested alongside the Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) algorithms on a three-phase, nine-level cascaded H-bridge multi-level inverter (CHB-MLI). Convergence, consistency, and speed tests have been conducted for these algorithms. After detailed validation through MATLAB simulations, the results were analyzed, and it was concluded that the DMO algorithm outperformed the mentioned algorithms in the modulation index range of 0.1 to 1.0. In conclusion, it has been demonstrated that the DMO algorithm can effectively optimize the THD value of the output voltage of CHB-MLI. [ABSTRACT FROM AUTHOR]

A method which uses the Fast Fourier Transform (FFT) is introduced to study the vibration control of a single-link flexible composite manipulator by input shaping. FFT method uses the impulse response of the system which can be obtained by ANSYS. Then, vibration responses are found by FFT method for various inputs. The vibration response is the time dependent acceleration signal of the selected output point. The method is verified on a 4-degree-of-system first. The responses found analytically by Laplace transform method, numerically by Newmark method, directly by ANSYS, and using the FFT method are compared. Then, a single link-composite manipulator is modeled in ANSYS, where natural frequencies and the impulse response are found. FFT method is used to find the vibration responses for inputs with various trapezoidal velocity profiles. The calculation time for the transient analysis is 22 h in ANSYS and 1 s for the FFT method. The natural frequencies found by ANSYS and the simulation results for the vibration responses found by the FFT method are compared with the experimental results. It is observed that they are in good agreement. It is noted that the deceleration time of the velocity profile is effective to control vibration. Considering the calculation times, the FFT method can be used to study the vibration control of complex mechanical systems by input shaping. [ABSTRACT FROM AUTHOR]

In this paper, an improved method for detecting light-flicker from multiple flicker sources which has a significant detrimental effect on power quality for power systems is proposed. The proposed method calculates the instantaneous flicker value directly from the frequency spectrum of the voltage signal unlike the standard IEC-61000-4-15 flickermeter known to give erroneous results in case of deviation of the fundamental frequency. Besides, owing to spectral corrections, this can also obtain the correct flicker value when the fundamental frequency deviates. Tests with synthetic signals have been generated in the presence of a single interharmonic frequency for different values, multiple frequency components and fundamental frequency deviations respectively, and then the instantaneous flicker values calculated by this method have been compared with IEC-flickermeter results. The method has been also used to calculate the flicker of field data obtained from busbars feeding electric arc furnace plants in the Electricity Transmission System of Turkey and the flicker-severity results have been compared with the results of the IEC-flickermeter. The advantage of the method is that it can swiftly and precisely estimate the flicker because of the reduction of it to arithmetic operations on Fast Fourier Transform(FFT) samples already calculated in many power quality analyzers. [ABSTRACT FROM AUTHOR]