Optimized Harmonic Reduction PWM based Control Technique for Three-Phase quasi Z-Source Inverter

This paper proposes an optimized harmonic reduction pulse width modulation (HRPWM) control strategy for three-phase quasi Z-source inverter (qZSI). In traditional sinusoidal or space vector pulse width modulation techniques, the flexibility in adjustment of individual switching angles is not possible and thus, these techniques are not optimum choices for low switching frequency operations of high/medium power qZSI. In the proposed technique, adjustments of switching angles of HRPWM waveform are possible to achieve optimum performance. The optimum performance is targeted as maximization of boosting factor and simultaneous minimization of weighted total harmonic distortion (WTHD) at the output voltage of qZSI. The hybrid particle swarm optimization gravitational search algorithm (PSOGSA) is used for computation of optimum switching angles of suggested HRPWM waveform at various modulation indices. The obtained WTHDs up to 49th order harmonics and boosting factors of optimized HRPWM methodology are compared with that of the maximum boost control (MBC) technique for qZSI to justify superior performances of the suggested method in low switching frequency range. The proposed concept has been verified via simulation study. The experimentation (qZSI controlled by microcontroller) validates the working of optimized HRPWM based qZSI which agrees with software results

Improved Preprocessing Strategy under Different Obscure Weather Conditions for Augmenting Automatic License Plate Recognition

Automatic license plate recognition (ALPR) systems are widely used for various applications, including traffic control, law enforcement, and toll collection. However, the performance of ALPR systems is often compromised in challenging weather and lighting conditions. This research aims to improve the effectiveness of ALPR systems in foggy, low-light, and rainy weather conditions using a hybrid preprocessing methodology. The research proposes the combination of dark channel prior (DCP), non-local means denoising (NMD) technique, and adaptive histogram equalization (AHE) algorithms in CIELAB color space. And used the Python programming language comparisons for SSIM and PSNR performance. The results showed that this hybrid approach is not merely robust to a variety of challenging conditions, including challenging weather and lighting conditions but significantly more accurate for existing ALPR systems

Performance of PLL based DSGCPS and FLL controlled SSGCPS under normal condition and different grid faults: A comparative study

This paper presents two separate studies to address the increasing need for renewable energy sources in the grid to cope with the rising energy consumption. Firstly, a Double Stage Grid Connected Photovoltaic System (DSGCPS) based on Phase Locked Loops (PLL) is developed using Matlab-Simulink. Secondly, a model of a single-stage grid-connected photovoltaic system (SSGCPS) controlled by a frequency locked loop (FLL) is created with comparable environmental parameters and a loading pattern. The research compares the active and reactive power flow dynamics and DC link voltage fluctuations of both systems. Results indicate that the SSGCPS is the preferred option due to its lower hardware requirements. However, it has a lower performance in cases of grid faults compared to DSGCPS. Moreover, the study analyzes the Total Harmonic Distortion (THD) of both models, a crucial factor for performance analysis. The comparative study shows that DSGCPS performs better than SSGCPS during fault in terms of THD. In conclusion, it can be inferred that both models have unique advantages and disadvantages, which are contingent on specific operating conditions

Adaptive shoot-through duty ratio control methodology of stand-alone quasi Z-source inverter

This paper presents an adaptive shoot-through duty ratio control methodology for a stand-alone three-phase quasi-Z-source inverter (qZSI). In practice, variable active and reactive load powers must be met by a qZSI-based stand-alone system. In this context, existing shoot-through control schemes for qZSI adjust the capacitor voltage or DC-link voltage at a fixed reference value. This causes extra voltage stresses on switches, high distortions, and an operating range reduction of the power inverter under variable load demands. On the contrary, the proposed shoot-through control scheme adjusts the shoot-through duty ratio adaptively based on load voltage feedback to improve performances. In this logic, the controllable shoot-through duty ratio facilitates various improved features in comparison to conventional schemes under load power variations. These features include reduced voltage stress across the switches, reduced distortions, and an extended operating range. The suggested proportional-integral (PI)-based scheme has a single control loop with a single measured quantity, i.e., sensing of load voltage only. The proposed concept has been verified via both simulation and experimental studies