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This article presents an innovative asymmetric multilevel inverter (MLI) topology that outperforms conventional counterparts. The introduced topology presents a breakthrough in implementing power electronics control by maximizing specific levels while minimizing switching components. A cutting-edge control scheme for optimal operation of the cascaded half-bridge MLI is presented. The ant lion optimization (ALO) algorithm was implemented to optimize the switching control to reduce the total harmonic distortion (THD) and improve power quality. For verification, the performance and effectiveness of the ALO technique are assessed by comparing its results to those obtained using the simplified sinusoidal pulse width modulation (SSPWM) technique, genetic algorithm (GA), and particle swarm optimization (PSO) in existing literature. Simulation results verified the efficacy of ALO in finding the optimal parameters. The suggested method showcases a remarkable reduction in the THD compared to SSPWM. The quality of the resulting waveform was enhanced, and both filter size and cost were significantly reduced. To meet stringent IEEE standards, an LC filter has been designed with minimal size and proper requirements. Experimental results validation of the suggested scheme, using a dSPACE R&D controller board unequivocally, confirmed its robustness and effectiveness. This groundbreaking study not only introduces a superior asymmetric MLI topology but also validates its exceptional performance through comprehensive analysis and experimentation. The experimental waveforms showed good matching with the simulation outcomes. The findings hold immense promise for advancing the field of power system control and revolutionizing the designing and implementation of efficient and cost-effective inverter systems. [ABSTRACT FROM AUTHOR]

The method of utilizing switched capacitors stands as an effective approach to achieve elevated voltage levels while minimizing the requirement for numerous DC sources through efficient utilization of stored energy in capacitors. This poses a significant challenge when designing high-voltage multilevel inverters with a reduced number of sources and switches. This study introduces a new boost-type multilevel inverter named the "nine-level switched capacitor–high-voltage gain boosting inverter" (9LSC-HVGBI). Notably, this specific configuration substantially reduces the DC source and capacitor count, necessitating only ten switches and a single DC source, along with two capacitors and three diodes, to produce a nine-level output. The described architecture offers several notable advantages, including a fourfold amplification capacity in voltage, automated balancing of capacitor voltages, and efficient management of inductive loads. Consequently, it demonstrates superior performance compared to other switched capacitor multilevel inverters in terms of minimal switch conduction at each level, restricting voltage stress on the switches to twice the input voltage, and optimizing efficiency. The proposed design is grounded in an intelligent series and parallel connection of switched capacitors. The study explores the operational concepts, with a specific focus on the mechanism for preserving capacitor voltage balance. The comprehensive loss evaluations and thorough comparisons with state-of-the-art alternatives substantiate its superior performance. Furthermore, the performance of the proposed 9LSC-HVGBI is validated through detailed simulation results across diverse test scenarios and experimental data collected in a well-equipped laboratory. [ABSTRACT FROM AUTHOR]

In the realm of electrical distribution, managing power quality is critical due to its significant impact on infrastructure and customer satisfaction. Addressing issues such as voltage sags and swells, along with current and voltage harmonics, is imperative. The innovative approach proposed in this paper centers on a dual-phase control strategy using a Universal Power Quality Conditioner that integrates series and parallel compensations to rectify these disturbances simultaneously. Our methodology introduces a hybrid control scheme that employs adaptive dynamic neural networks (ADNN), a sinusoidal tracking filter (STF), and a proportional-integral (PI) controller optimized via an improved krill herd (IKH) algorithm. The first phase utilizes the ADNN-based adaptive integrated estimator for quick and accurate disturbance detection and estimation. Subsequently, the second phase employs the STF, omitting the Low Pass Filter and employing a Phase Locking Loop to generate precise reference voltages and currents for the series and parallel active filters based on dynamic load and source conditions. This advanced control mechanism not only enhances system efficacy but also reduces the need for extensive computational resources. Furthermore, the performance of both series and parallel inverters is finely tuned through a PI controller optimized with the IKH algorithm, improving the DC link voltage regulation. Our extensive testing under various conditions, including voltage imbalances and harmonic disturbances, demonstrates the robustness of the proposed solution in both transient and steady-state scenarios. [ABSTRACT FROM AUTHOR]

Fault diagnosis and detection in electrical power systems need a development of new and robust supervision structures. In the last years, different intelligent monitoring methods have been successfully proposed to deal with the problem of fault diagnosis in power transmission lines. In this work, a new hybrid strategy called FFT-FL combining Fuzzy Logic (FL) approach with Fast Fourier Transform (FFT) is proposed and applied to fault diagnosis in power line network. The elaborated fault detection structure consists of indicating whether the electrical transmission is working correctly or a fault has occurred with an effective isolation step to determine the faulty zone in the line. Whereas, an identification step consists of determining faulty phase thus fault classification in the studied line network. The novel proposed algorithm (FFT-FL) is used to improve the fault diagnosis response time and to decouple between faults and disturbances. In this paper, a comparative study is presented between the two intelligent methods for detection, isolation and identification of faults using only FL and the hybrid FFT-FL structure. The obtained simulation results verify the effectiveness and the correctness of the proposed fault method for all types of faults in the power line networks and in different zones. [ABSTRACT FROM AUTHOR]

In this work, a novel SRF-PLL and DSOGI-PLL with the JAYA based optimization approach is presented herein for the control of a unified power quality conditioner (UPQC) system. The proposed UPQC system is linked to a three-phase distribution system that has nonlinear loads. Increased use of non-linear loads has contributed to harmonic effluence in power distribution systems and thus power quality issues have been elevated which is essential to be efficiently addressed. Since, the UPQC consists of a shunt and a series filters therefore, it is a most promising custom power device to mitigate power quality issues of instance voltage swell, sag, phase unbalance, current and voltage harmonics, DC-link voltage regulation, reactive power compensation etc. SRF-PLL and DSOGI-PLL perform grid synchronization and reference signal generation simultaneously in a single platform. Additionally, JAYA based optimization has been employed for determination of PI controller gains of both the controller. To validate the performance of UPQC and its controller, the complete UPQC system has been developed and fabricated in MATLAB/ Simulink as well as in hardware platform. The accuracy of simulation as well as hardware outcomes and their comparative power quality investigation is found to be satisfactory. [ABSTRACT FROM AUTHOR]

Purpose: The paper presents the design and model of energy harvester prototype consisting of vibration generator and magnetic spring. The developed magnetic spring prototype, which is integrated in the vibration generator, detects several resonance frequencies significant for energy harvester optimization and ensures more applications in engineering technology. Methods: The magnetic spring with two identical fixed magnets and the movable permanent magnet that levitates between the two fixed magnets in a vertical direction and moves linearly, can harvest multi-directional environment vibration resembled by vibration generator. The magnetic spring acts as the clamping system for the levitated magnet. Mechanical energy gained through vibrations resembled by vibration generator is converted by the magnetic spring into electrical energy. Results: Numerical calculations and experimental tests including measurements of I–V, total harmonic distortion (THD) of displacements and magnetic induction conducted in Laboratory have been useful to determine the characteristics and performance of the magnetic spring integrated in electromagnetic vibration generator. Conclusion: The I–V impedance measurements have exhibited a significantly stronger dependence on frequencies resonances and the measurements of magnetic induction intensity show the demagnetization and magnetization processes of the levitated permanent magnets. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) have been widely accepted in several industrial applications. The advantages provided by MLI are achieved only through the use of several semiconductor switches and capacitors; consecutively increase the total system cost and complexity. To overcome the above limitations, this article develops a reduced device count hybrid MLI topology. The proposed MLI topology (PMLIT) can produce a 9-level voltage waveform with symmetrical sources and a 7-, 11-level output voltage waveform with asymmetrical sources using a single cell. In addition, PMLIT can be extended to produce any number of voltage levels by cascade connection of the cells with the built-in ability to produce both negative and positive voltage levels. Also, the voltage across the used capacitor is self-balanced without the use of any external components. The comparative investigation reveals the superior characteristics of the PMLIT in terms of the components and total blocking voltage over the newly and conventional topologies. Also, the calculated cost function shows that the PMLIT is more economical than the recently developed topologies. Finally, the viability of the PMLIT has been validated by conducting various tests on the simulation platform and also experimentally for 7, 9, 11 and 81 levels under diverse operating conditions. [ABSTRACT FROM AUTHOR]

In this paper, an improved Beetle Antenna Search (BAS) algorithm is developed for Maximal Power Point Tracking (MPPT) in a double-stage three-phase solar grid-integrated system. The behavior of the beetle foraging approach yields maximal power from photovoltaic string with the sustained duty cycle through an optimal BAS MPPT controller. The BAS algorithm succeeds in the purpose of achieving the optimum duty cycle of the DC–DC boost converter for the Solar Photovoltaic System. The intended controller is achieved in step and ramp varying irradiation environment at the specified temperature. The outcome of BAS MPPT has maximal power and better tracking speed with less fluctuation than the P&O controller. Also, the BAS algorithm affords the effortless function of load stabilizing and harmonics decrement in grid performance. The proposed controller has better improvement than the conventional algorithm by reducing training data time, decreasing the sample size, and retaining the selected permissive data. Simulation illustrations prove the quick response time, and acceptable behavior in step and ramp irradiation conditions. Further, an illustration shows the ability to enhance the stability of power in the grid with reduced oscillation and distortion factors. The harmonic distortion of voltage and current is obtained within the control limit of universal standards. The simulated results are validated in MATLAB/Simulink environments. [ABSTRACT FROM AUTHOR]

This proposed work deals with the implementation of a single-phase topology with using hybrid for multilevel inverters. It is observed that the proposed structure improves the performance of the hybrid multilevel inverter with high-frequency switches for positive levels and reverse voltage with negative levels. This paper studies a novel construction for an asymmetrical hybrid single-phase multilevel inverter. This paper also studies the operation of multi level inverter under depreciating sources condition due to fluctuation in input. The PWM method, i.e. APOD and CO, has been incorporated into the simulation of single-phase 7-level, 9-level, and the 11-level hybrid inverter. These two methods are compared to one another and to standard methods in terms of THD for different values of the modulation index, and they are found to be superior. Overall loss of 50% of the THD is almost equal to rated output voltage, it is observed in cascaded multilevel inverters. The working and performance of the proposed model are simulated in MATLAB Simulink software and the results are discussed in detail. [ABSTRACT FROM AUTHOR]

The power quality (PQ) improvement employing appropriate intelligent controllers is identified as a suitable solution for the dependable, safe, and stable operation in the electric utility systems (EUS). Hence, this paper proposes new types of neural network (NN) based Greedy Least Mean Square (GLMS) controllers for distributed static compensators (DSTATCOM). First, the EUS is developed by considering current source-based non linear load using the MATLAB/Simulink environment. Next, both controllers are implemented by their own learning principle using embedded systems toolboxes. The proposed scheme combines different weighting factors like step size, learning rate and convergence factor to achieve the approximate tuned weight. Then, the final weighting components are achieved by adding DC and AC PI controller weights corresponding to the mean value of active/reactive weight of load currents for the triggering pattern. The proposed control algorithm provides a precise control for the system by maintaining reduced voltage across the self-braced capacitor as compared to the Adaptive Least Mean Square (ALMS) controller. The other PQ merits like better voltage regulation, load balancing, total harmonic distortion (THD) suppression, and power factor (P.F) improvement are attained. Finally, experimental results obtained from the proposed controller fulfill all the shunt-related PQ requirements as per IEEE benchmark for the different case studies. [ABSTRACT FROM AUTHOR]

Harmonic estimation is a crucial challenge in the current microgrid/smart grid-based system, as integrating renewable sources into the grid injects multiple orders of harmonics into the system. Thus, the amplitude and phase parameters of the harmonic components need to be estimated correctly. Adaptive filtering-based models efficiently track the time-varying harmonics present in the system. In this paper, a detailed comparative analysis is made using Volterra and bilinear adaptive estimation models while tracking the amplitude and phase parameters. The main idea behind the development of efficient harmonic estimator is based on the integration of Volterra and Bilinear expansion blocks to the objective functions of LMS and LMS/F algorithms. Most importantly, the distorted voltage signals generated from the single-phase inverter model, the PV-based model, and an IEEE voltage signal dataset are used to observe the harmonic estimation accuracy of different models. The quantitative performance comparison is made with other least LMS families of estimation models by calculating THD and MSE. A separate section is included to explain the FPGA modeling of the harmonic estimator by integrating the hardware board. [ABSTRACT FROM AUTHOR]

In recent decades, grid-connected photovoltaic (PV) systems have been increasingly utilized worldwide for their role in renewable energy generation and sustainability. Among power electronic configurations, the multi-level inverter (MLI) is famous for its efficiency in reducing total harmonic distortion (THD) and distributing power across several switches, enhancing power quality. However, using many switches increases energy losses and system complexity, making optimization crucial. Additionally, the power output from PV arrays is heavily dependent on environmental factors like temperature and solar irradiation, necessitating maximum powerpoint tracking (MPPT) techniques through advanced switching algorithms. These algorithms ensure that the system operates at its optimal point, extracting maximum energy from the PV array under varying conditions. Consequently, THD can be affected by these variations, complicating performance further. This paper proposes a Z-source-based MLI, providing additional benefits in power conversion efficiency and flexibility. This design employs a lower-frequency switching method for MPPT, executed in the Z-source part of the inverter during the shoot-through (ST) state, ensuring that THD remains unaffected by the MPPT process and improving system stability. This model is simulated in MATLAB to verify its performance under different conditions. Results illustrate an efficiency of over 96%, while maintaining a steady-state THD of 4.58%, confirming the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

Power loss and malfunctioning of equipment due to current and voltage harmonics produced by nonlinear loads are major concerns for both power suppliers and consumers. This paper employs DSTATCOM to mitigate these harmonic distortions in distribution systems. DSTATCOM is a current controlled voltage source PWM converter with passive components. It supplies compensating current that eliminates current harmonics and provides reactive power compensation thereby providing a smooth source current. The performance of DSTATCOM is controlled using proportional integral and fuzzy logic–based control (FLC) schemes to improve power quality at dynamic loading. As the penetration of photovoltaic (PV) systems in energy production is significant, the power quality issues for PV-integrated systems have also been investigated. The maximum power point for a PV array is tracked using perturb and observe and FLC methods. The complete system is simulated in MATLAB and extensively investigated for a large range of balanced and unbalanced nonlinear load conditions. The simulation results are validated in real time through the hardware in loop (HIL) test bench using Opal-RT controller. The proposed PV-integrated DSTATCOM with FLC yields better performance in terms of DC link voltage settling time, total harmonics distortion, and smooth source current as compared to other schemes. [ABSTRACT FROM AUTHOR]

In microgrids (MG) with a high penetration of renewable energy sources (RES) power converters are used to regulate the produced energy to a single voltage and frequency reference value across the MG. Adequate incorporation of an LC filter at the output of power electronic devices allows the attenuation of harmful harmonics that can be introduced to the MGs energy bus. By traditional methods, LC filter values can be calculated by means of the power rating, switching frequency, cutoff frequency, and using the bode frequency domain. Nonetheless, in the transition from a connected to an autonomous MG operation, the calculated LC filter can lead to high harmonic injection. As a result, a tuning methodology capable of obtaining the right set of parameters for the LC filter for a transition event can improve the performance of the MG. This work optimizes the LC output parameters with respect to the size of the filter components, the IEEE Std 519-2014, and bandwidth of the filter, within a bounded region of values subjected to performance conditions such as voltage output, and the produced total harmonic distortion (THD) measurements during the transition from a connected to an autonomous operation. In a case study, genetic algorithm optimization is used to obtain the LC filter parameters and compared to a conventional arithmetic methodology to obtain the values of the filter. The optimization results in a set of values that lead to a higher harmonic attenuation after the transition rather than a conventional method using the switching frequency as the main design factor. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) are widely preferred in sustainable power applications for their ability to deliver efficient output with low total harmonic distortion (THD) while minimizing the use of power semiconductor components. The single-sourced multilevel inverter based on switched capacitors has fewer components and better boosting. The proposed design eliminates the need for large DC–DC converters and transformers commonly used in traditional systems by incorporating switching capacitors. Furthermore, the self-balancing nature of these capacitors eliminates the necessity for additional sensors or control algorithms. In addition to supporting both symmetric and asymmetric configuration, the design achieves twice the voltage gain with a lower total blocking voltage (TBV). The ANN-based Newton–Raphson (NR) method, combined with selective harmonic elimination, can achieve a reduction in total harmonic distortion by up to 6%. A lower total blocking voltage, less losses, a smaller component count and an enhanced gain factor are some of the benefits of the system. In addition, the suggested system has an efficiency of up to 96% and lower overall voltage stress. Experimental validation under varying conditions has been conducted in addition to simulations using MATLAB/Simulink to assess the dynamic performance and operation of the suggested topology. [ABSTRACT FROM AUTHOR]

Due to the many semiconductor switches used in power conversion, switch failures are more common in multilevel inverters (MLIs). Therefore, designing an MLI with fault-tolerant (FT) capability is of utmost importance for uninterrupted supply. This article demonstrates various fault scenarios and offers numerous switching strategies for the different fault combinations. The detailed analysis of the proposed topology in terms of single (FT1), double (FT2), triple (FT3), quadruple (FT4), and quintuple (FT5) switch failures has been discussed in detail. The proposed topology uses phase disposition sinusoidal pulse width modulation (PD-SPWM) for gate signal generation. Further, a brief comparison analysis of the proposed topology in terms of device count, total blocking voltage (TBV), pre-and post-fault voltage level, pre-and post-fault voltage magnitude for the various fault combinations have been performed and compared with the exact nature of the available topology. The reliability analysis of the proposed topology has also been done mathematically. The simulation study of the proposed topology has been carried out in the MATLAB/SIMULINK environment for all possible switch fault combinations, and real-time validation is also done in OPAL-RT 4510. [ABSTRACT FROM AUTHOR]

The modular multilevel grid following string inverter (MMGFSI) has gained popularity in large rooftop solar photovoltaic power (PV) plant applications, with grid-integrated net metering facility. The performance of the standard PI controller-based MMGFSIs during grid load disturbances is not satisfactory due to the wide ripples, low dynamic performance, and low steady-state precision of the inverter current feedback regulation. This study proposes a repetitive control proportional-integral (RCPI) controller approach for the cascaded H-bridge (CHB) five-level grid following inverter to synchronize with the grid and satisfy enhanced power quality standards IEEE519 for large rooftop solar PV plant application system. Additionally, this proposed control topology performance has compared to PI controller-based MMGFSI’s and repetitive controller cascaded PI controller-based MMGFSI’s system. The proposed RCPI MMGFSI’s system performance has been tested on a PSIM simulation environment on a grid-connected, photovoltaic (PV) system with a diversity of linear and nonlinear load disturbances to show the viability and resilience of the suggested repetitive control strategy in practice. To provide the necessary carrier control signal for the sinusoidal pulse width modulation block (SPWM), a cycle delay has introduced in the RCPI feedback path. As a result, reducing grid-side harmonic distortion lowers the cost of the LCL filter connected to the inverter output This RCPI-based MMGFSI has 4.1 percent less overall harmonic distortion than the conventional PI controller-based MMGFSI and 0.21 percent less total harmonic distorted than repetitive cascaded PI controller-based MMGFSI’s system. Additionally, a hardware prototype has RCPI controller MMGFSI’s implemented to evaluate the five-level CHB MLI structure and switching topology. [ABSTRACT FROM AUTHOR]

Smart lighting is considered an emerging trend in the global lighting industry. In terms of scale, expense, and performance, smart LED lighting applications are more advantageous. However, the input current of the power supply used for driving LEDs is more polluted due to the presence of switching devices, thereby lowering the power factor (PF). The bridge circuit of conventional DC–DC converters that use a diode bridge rectifier (DBR) as an interface between the main supply and the LED load have substantial losses and hence offers low efficiency. It also presents adverse power quality problems in the supply current resulting in poor PF. In this paper, artificial bee colony optimization algorithm-based closed loop digital proportional integral controller design and implementation of modified Type-III Bridgeless Cuk (BLCUK) LED driver are presented to obtain unity power factor and higher efficiency for smart lighting applications. MATLAB software is used to conduct the computer simulation analysis of the BLCUK converter. The experimental prototype is developed and tested using C2000 32-bit Microcontroller TMS320F28027. The digital controller (2P2Z-two poles two zeros controller) is implemented for the proposed control scheme, and the obtained experimental results are in consonance with the simulation outcomes. [ABSTRACT FROM AUTHOR]

Power quality management is a widespread requirement in this renewal energy source (RES) integrated environment. A few of the key challenges faced during power quality management are total harmonic distortion (THD), poor power factor and reactive power compensation. This paper tries to improve these power quality issues using synchronous reference frame (SRF) theory-based distributed static compensator (DSTATCOM). An Adaptive Neuro-Fuzzy Inference System (ANFIS) algorithm has been used to optimize the operation of the DSTATCOM and to obtain maximum power from a PV array. This algorithm optimizes the requirement of compensating current from the PV fed DSTATCOM to make the source current smoother. System dynamic performance is investigated in the presence of balanced/unbalanced nonlinear and reactive loads. The results obtained using ANFIS- and SRF-based methods are compared to other conventional/AI-based methods and found to be superior. The proposed method is validated in real time using Opal-RT on FPGA computation engine to closely emulate actual hardware. [ABSTRACT FROM AUTHOR]

The control algorithm of a DSTATCOM majorly influences its function. The key role of a phase locked loop (PLL) as a fundamental extractor in the control algorithm is inevitable. It is used to extract the information of the fundamental like phase angle, frequency and amplitude from the distorted voltage/current signal. According to the information collected, the performance of the control algorithm of the DSTATCOM is judged for various conditions like unbalanced and distorted harmonic condition. This paper presents the study of three PLLs, namely unified three-phase signal processor PLL (UTSP), multi-sequence harmonic decoupling PLL (MSHDC) and harmonic/inter-harmonic DC offset (HIHDO) PLL. An unconstrained optimization problem has been formulated with DC and AC bus voltage errors. The gains of proportional integral controller are projected using RAO algorithm. It is an algorithm specific type and parameter less. The DSTATCOM is able to compensate the reactive power and mitigate the grid current harmonics which are caused due to a nonlinear load through an optimized PI controller for the considered PLL the control algorithms. An analysis of performance using simulation results, dynamic response and complexity in computation has been made for the PLLs considered. The fast recovery during dynamic conditions of the system has opted HIHDO PLL as better one among the other two proposed PLLs. The laboratory performance of the considered system for HIHDO PLL using d-SPACE has been provided. [ABSTRACT FROM AUTHOR]

In this paper, the PI (Proportional Integral) controller tuned with the Whale optimization algorithm (WOA) has been designed for the hybrid series active power filter (HSAPF). The PI controller here is used to set the DC link capacitor voltage to a fixed value. The controller parameters have been tuned with WOA technique to improve the performance of the controller. The WOA technique adopts a shrinking mechanism that helps to cover the entire search space so that the chances of getting the optimal parameters are high. To generate the gate signal pulse width modulation technique has been used. In order to justify the above proposed technique a Simulink model has been developed in MATLAB and the results are compared with those obtained from the existing techniques such as particle swarm optimization (PSO), Grey wolf optimization (GWO), and teaching learning-based optimization (TLBO). The simulation results show that the above proposed technique is superior to the existing techniques as it certainly gives promising results in supressing the harmonics in the system to the desired level as per the IEEE standard 519. [ABSTRACT FROM AUTHOR]

This paper proposes the reduction of common mode voltage (CMV) magnitude using a simplified logical modulator (SLM). This modulator uses the ideas of space vectors to detect and eliminate the high common mode vectors produced by carrier phase-shifted sine pulse width modulation generator. The proposed SLM has an inherent ability to eliminate the CMV spikes due to dead time, but it introduces short circuit vectors (SCVs). This issue is addressed by designing an SCV eliminator (SCVE). The performance of the SLM-SCVE is validated through simulations. The proposed SLM-SCVE is implemented using MATLAB—Xilinx system generator interface in Spartan 3E–FPGA and tested in a prototype hardware. The proposed SLM-SCVE proves to be a simple and reliable solution for the reduction of CMV in industrial application because finite number of logic gates is used. [ABSTRACT FROM AUTHOR]

A new 28 kHz is proposed for the generation of output power of 775 watts with a high frequency to drive a domestic induction heating application using AC convertor. The proposed system deals with the output parameters of THD, PF, and output power in the simulation. The simulation carried out for the various loaded conditions and selected with respect to various parameters like power factor, THD, temperature, time, higher power, uniform distribution of heat through the IH system. The requirement of the proposed system is to have a highly reliable and adaptable to different loaded condition. A prototype of the proposed system was implemented and verified with the system developed. Experiment was carried out with different medium (liquid) and results are measured and graphically represented. The validations of the electrical and thermal parameters are focused in the proposed and implemented system. [ABSTRACT FROM AUTHOR]

A three phase Vienna rectifier topology is proposed with a modified inductor and control models. The presented switched inductor structure works during the active switch turn on and turned off condition. So, voltage gain of the converter will be improved and the stress across the active switch due to voltage will be reduced. Here, (PSO) Particle Swarm Optimization algorithm-based control model is utilized to optimize the gain parameters of bidirectional active switch with required switching frequency. By using the capacitor voltage and the switched inductor current for gain adjustment through the light load and full load condition. So, the proposed topology reduces the (THD) Total Harmonic Distortion present in the inductor current and improves the power factor at both the continuous and the discontinuous conduction mode. The proposed circuit is applied using MATLAB/simulink and analyzed by comparing with feed forward compensation method and implemented in hardware using Field Programmable Gate Array (FPGA). [ABSTRACT FROM AUTHOR]

Nowadays, grid-connected photovoltaic (PV) power system is quite popular in many countries. For grid-connected PV power system, to achieve maximum power and good power quality of the system are considered as big challenges. In order to achieve this, artificial intelligent (AI) controller-based maximum power point tracking (MPPT) algorithm has been investigated for PV system as well as a new cascade multilevel inverter (MLI) is proposed for grid integration of PV system. The proposed cascade MLI has been designed with a smaller number of power electronic switches and it can be operated at asynchronous voltage sources, which is most adaptable for PV system. This proposed inverter can reduce the total harmonic distortion (THD) at output side by means of increasing the output voltage level with this power quality of the system has been improved. The microgrid integration of proposed inverter has been controlled by using AI-based voltage source controller and this proposed system is designed and simulated in MATLAB environment at various weather conditions and loading conditions. Finally, prototype model has been developed in laboratory and evaluating its performance. The simulation results and prototype results were verified with IEEE 1547 standard that proves the proposed system effectiveness. [ABSTRACT FROM AUTHOR]

One of the most critical elements in the connection of photovoltaic (PV)-based systems used to generate electricity from solar energy is the inverter. The harmonic effects of the inverters to be connected to the grid should be as low as possible, and the total harmonic distortion (THD) should be less than 10%. A high THD value will distort the power quality on the grid side. For this reason, the THD value of the inverters in the grid connection approaches must be determined by spectral analysis to ensure that the necessary protection and improvements are made technically. In this study, a novel inverter topology, including six power switches and two power diodes, is presented, and the voltage data obtained from a grid-connected inverter are acquired in real time, and spectrum analysis is performed with the software developed with LabVIEW. The power efficiency of the proposed inverter is compared with conventional inverter types such as HERIC, H5, and H6 inverters. One of the novelty aspects of the proposed inverter topology is forming a proper freewheeling path including switches and diodes in the inverter branches that can provide a separate DC and ac components, and as a result, this prevents the following the PV side leakage currents to the ac grid side. In the spectrum analysis, the chirp Z-transformation (CZT) was used along the contours of the Z-transformation outside the unit circle. Using CZT, the z-transform was calculated for the inverter output voltage along the spiral lines in the z-plane. Besides, spectrum analysis was performed with fast Fourier transform (FFT) and compared with CZT. The results show that the CZT transformation is more efficient than the FFT algorithm and is useful in calculating a subset of FFT for a sequence. The performance of the proposed inverter is compared with conventional topologies. Hardware implementation and the output signals and the leakage current waveforms are also presented. [ABSTRACT FROM AUTHOR]

Multilevel inverters are finding wide application in electric drives, traction, flexible AC transmission systems (FACTS) and renewable energy systems. A cascaded H-bridge type multilevel inverter (CHBMLI) produces a near sinusoidal output voltage with lower switching stress and a higher conversion efficiency than the other types of MLIs. The Selective Harmonic Elimination (SHE) strategy is used to eliminate lower-order harmonic profiles and to regulate the fundamental component in the output voltage. SHE has the advantages of low switching frequency, low switching losses and low stress. In this paper, the modulation index and input voltage values are also considered as optimization variables along with the conventional switching angles to analyze the performance improvement in selective harmonic elimination. Heterogeneous Comprehensive Learning Particle Swarm Optimization (HCLPSO) and Gravitational Search Algorithm (GSA) algorithms are used to find the optimal switching angles, modulation index and input voltage source values for minimizing the lower-order harmonics present in the output voltage of seven-level and eleven-level CHBMLIs, while maintaining the fundamental component of the output voltage. The results obtained from MATLAB simulations and an experimental setup clearly indicate that the proposed HCLPSO-based multilevel inverter provides better performance when compared with GSA, firefly and Differential Search Algorithm (DSA)-based MLIs. [ABSTRACT FROM AUTHOR]

Voltage source converter (VSC)-based multiterminal high-voltage direct current (HVDC) systems received widespread attention throughout the world for grid integration of renewable energy resources in recent years. This paper presents a comparative performance analysis of different VSC-based outer control and inner current controllers for the multiterminal HVDC system. It employs either lead-lag (LL) or proportional–integral (PI) controllers for outer DC link voltage control, whereas it uses PI or model predictive controllers (MPCs) for inner current control. Hence, it designs four combinations of controllers (LL–MPC, LL–PI, PI–MPC, and PI–PI) to control the outer DC link voltage and inner current of the VSC-based multiterminal HVDC system. Besides, it proposes an integral time squared-error (ITSE)-based optimization technique to tune the parameters of the employed PI controllers that selects optimal parameters at minimum ITSE under extreme operating condition. The combination of the mentioned controllers forms the main control unit of the multiterminal HVDC transmission network for regulation of the DC link voltage and the power flow. Moreover, this article evaluates the controller performance in terms of maximum overshoot, steady-state error, settling time, rise time, and total harmonic distortion. It implements the proposed controllers in a typical VSC-HVDC system and multiterminal HVDC transmission system in MATLAB/SIMULINK platform. Presented results confirm the efficacy of the four-type controllers. The optimized PI–MPC controller provides overall better performance relative to other controllers. [ABSTRACT FROM AUTHOR]

The Kachchh rift basin (KRB), located in the western continental margin of India, is very important due to repeated large magnitude occurrence of intraplate earthquakes. The present study elucidates the subsurface structural features using wavelength filtering, total horizontal derivative (THD) and 2.5 dimensional (2.5D) density modelling of the gravity data. Power spectrum analysis of the gravity data gives the cut-off wavelength of 100 km that has been used for wavelength filtering for regional-residual separation. The residual gravity anomaly significantly enhances the shallow features (like Allah-Bund fault, Kachchh mainland uplift, Wagad uplift, and Pachham uplift) and gives an NW–SE subsurface structural trend. The predominant direction for major lineaments derived by the THD of gravity data shows the ENE–WSW as well as NE–SW and NW–SE directions. The 2.5D density model of the regional gravity anomaly reveals the presence of high-density magmatic underplating layer and intrusive mafic body in the lower crust that is in accordance with the previous studies. The regional slope of the Moho in the KRB is towards the SW direction. An intrusive mafic body in the lower crust and volcanic plugs in the upper crust act as stress concentrator which is responsible for seismicity in the KRB. Several new lineaments have been identified based on the present study, which may be accountable for seismicity over the different part of KRB. [ABSTRACT FROM AUTHOR]

Purpose: To compare the results of laser hemorrhoidoplasty (LHP), excisional hemorrhoidectomy (EH), and sutured mucopexy (MP). Methods: A randomized, parallel-group, double-blinded, single-center prospective study. Patients: Symptomatic 2nd- or 3rd-degree hemorrhoids patients. Interventions: Computer randomization sequence, patient blinding, operating surgeon blinding, and surgeon-evaluator blinding. LHP was performed using a 1470 nm diode laser. Up to 250 J of energy delivered per 1 hemorrhoid. The procedure was performed circumferentially. MP ligations were placed in the area of visible hemorrhoidal tissue. Standard EH was performed up to the level of the hemorrhoidal pedicle. Follow-up at 1 and 6 weeks and 1 year. Outcome measures: Recurrence of symptoms requiring treatment, intensity, and duration of pain after the operation, patients' quality of life, fecal incontinence, and patients' evaluation of treatment. Results: A total of 121 patients. Groups were even preoperatively. LHP took 15 min (SD 5.6), MP took 16 min (SD 5.58), and EH took 29 min (SD 10.3). Recurrence requiring treatment rate was 0% after EH, 10% after LHP, and 22% after MP, p = 0.004. LHP and MP were less painful than EH, p < 0.001. Patients after LHP returned to regular activity after 15 days, after MP after 22 days, and after EH after 30 days, p < 0.001. SF-36 scores were better after EH. Symptoms of fecal incontinence improved in all the groups. Patients evaluate LHP better than EH and MP. Limitations: Single-center study. Conclusions: Laser hemorrhoidoplasty is a safe, minimally invasive option for hemorrhoids, more effective than MP and less effective than EH. Patients evaluate this technique better than the other two. [ABSTRACT FROM AUTHOR]

Introduction: Doppler-guided transanal hemorrhoidal dearterialization (THD) was considered a less invasive and innovative method to treat hemorrhoidal disease, but it may impact the anal area during dearterialization and mucopexy. Thus, this study aimed to assess any changes in anorectal manometry of grade III and IV hemorrhoidal patients following THD treatment.Methods: This prospective observational study was conducted with patients who had grades III and IV hemorrhoidal disease. The patients were treated using THD at the Department of Surgery in the National Hospital of Traditional Medicine (Hanoi, Vietnam) between June 2012 and December 2013. Anorectal manometry was performed prior to THD and again between 6 and 12 months following the procedure.Results: A total of 40 patients were enrolled in the study, including 32 with grade III hemorrhoids and 8 with grade IV hemorrhoids. The proportion of male patients (65%) was higher than that of female patients (35%), and the majority of patients (82.5%) were > 40 years old. The mean duration of symptoms prior to treatment was 12.3 years. The mean length of the anal sphincter was unchanged before and after THD (3.64 ± 0.40 cm prior to treatment vs. 3.66 ± 0.48 cm following treatment; p = 0.57). Significant differences in treatment-related changes were detected for all anorectal manometric measurements except maximum squeezing pressure (p < 0.05). No patient showed anal stenosis or fecal incontinence.Conclusion: The THD technique did not change the length of the anal sphincter 6 months after hemorrhoid treatment. The values of anal pressure and rectal sensation decreased almost significantly between treatment and the follow-up visit. We suggest that further studies, which include larger sample sizes, should be conducted to confirm THD effectiveness in terms of anorectal functions. [ABSTRACT FROM AUTHOR]

High progresses in the field of power electronic create an appropriate bed to introduce new and upgraded multilevel inverter topologies. Such these topologies contain remarkable inherent advantages like: high quality staircase sinusoidal output voltage, low number of switches, low peak inverse voltage, et cetera. In this paper, a novel modular asymmetrical multilevel inverter is proposed to reduce the number of inverter's components, and accordingly make a cost-effective structure with excellent voltage-step creation. In accordance with the configuration of utilized switches and magnetite of DC voltage source, the proposed structure can provide a high-step staircase sinusoidal voltage without high increase of semiconductors. Consider this; symmetrical condition of the proposed structure also takes low number of switches as compared to other symmetrical structures. Finally, both the MATLAB/SIMULINK and experimental results have confirmed the accurate operation and voltage-step creation capability of the suggested multilevel inverter. [ABSTRACT FROM AUTHOR]

This paper proposes a methodology for single-phase power factor correction with DC–DC single-ended primary inductance converter (SEPIC) using cascade control strategy which comprises of genetic algorithm-based outer PI controller and an inner current controller which uses an adaptive neuro-fuzzy inference system-based sliding mode controller. DC–DC SEPIC is a fourth-order converter, and in order to reduce the complexity in controller design, reduced-order model of the original higher-order system is obtained by using Type-I Hankel matrix method. The performance of the proposed system is analysed using MATLAB/Simulink-based simulation studies. In order to ensure the robustness of the proposed controller, the performance parameters such as percentage total harmonic distortion, power factor, % voltage regulation, and % efficiency are analysed. From the simulation results, it is inferred that the proposed method provides efficient tracking of output voltage and effective source current shaping for load, line, and set point variations. [ABSTRACT FROM AUTHOR]

In this paper, operational transresistance amplifier (OTRA) based Wien bridge oscillator is presented which uses an OTRA, two RC sections, and a buffer. The frequency of oscillation and the condition of oscillation have been derived, and the effect of device non-ideality on these parameters has also been analyzed. Further, harmonic analysis is carried out to characterize the linear performance of the proposed oscillator. Workability of the proposed Wien bridge oscillator is verified through SPICE simulations followed by experimental results. The total harmonic distortion (THD) is calculated and found to be less than 1%. Low THD value is a significant performance criterion for many high frequency applications. [ABSTRACT FROM AUTHOR]

In this paper, the delay problem of a deadbeat current control for a single-phase PWM inverter connected to the grid is investigated by applying z-transform. First, the effect of delay during one sampling period is discussed and then a predictive current observer-based controller is considered. The main objective of the control system is that the current has minimum harmonic distortion, and is in phase with the grid voltage. The control system has fast dynamic response when distortion occurs, and is robust against drift in the system parameters; it also places all the system closed-loop poles at the origin of the z-plane. Hence, it can achieve fast dynamic response with low total harmonic distortion, even under nonlinear loads. The simulation results are performed to verify the feasibility of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper presents a novel reconfigurable selective harmonic elimination technique to control harmonics over a wide range of Modulation Indexes (MI) in Multi-Level Inverter (MLI). In the proposed method, the region of the MI is divided into various sectors and expressions are formulated with different switching patterns for each of the sectors. A memetic BBO-MAS (Biogeography Based Optimization - Mesh Adaptive direct Search) optimization algorithm is proposed for solving the Selective Harmonic Elimination - Pulse Width Modulation (SHE-PWM) technique. An experimental prototype is developed using a Field Programmable Gate Array (FPGA) and their FFT spectrums are analyzed over a wide range of MI using a fluke power logger. Simulation and experimental results have validated the performance of the proposed optimization algorithms and the reconfigurable SHE-PWM technique. Further, the sensitivity of the harmonics has been analyzed considering non-integer variations in the magnitude of the input DC sources. [ABSTRACT FROM AUTHOR]

This paper introduces a design of a sensorless control of a five-phase permanent magnet synchronous motor drive working at low and zero speeds with low current distortion. The rotor position is obtained through tracking the saturation saliency. The saliency position is tracked through measuring the dynamic current response of the motor line currents due to the insulated-gate bipolar transistor switching actions. It uses the fundamental pulse width modulation (PWM) waveform obtained using the multi-phase space vector pulse width modulation only. The saliency tracking algorithm used in this paper does not only improve the quality of the estimated position signals but also guarantees a minimum current distortion. It reduces the modifications introduced on the PWM waveform. Simulation results are provided to verify the effectiveness of the proposed design over a wide speed range under different load conditions. [ABSTRACT FROM AUTHOR]

In order to further improve the harmonic suppression capability of conventional 12-pulse rectifiers, this paper proposes a low harmonic 12-pulse rectifier using an Active Inter-Phase Reactor (AIPR). Through a detailed analysis of the relationship between the input current, output current and circulating current of the DC side, the mechanism where the AC grid side current harmonics can be suppressed by the DC side circulating current is revealed. On this basis, an interleaved APFC controlled by a DSP is designed and used as an AIPR along with an interphase reactor. A simulation is carried out with MATLAB/Simulink and an experiment is performed on a 9-kVA prototype. The obtained results verify the feasibility and validity of the proposed approach. Compared with a traditional 12-pulse rectifier, the THD can be reduced to 1/5 of the original value, and the capacity of the AIPR is only 2% of the load power. Thus, it is suitable for high-power applications. [ABSTRACT FROM AUTHOR]

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Background: Approximately one in five persons living in the USA is maintained on oral anticoagulation. It has typically been recommended that anticoagulation be withheld prior to hemorrhoidal procedures. Transanal hemorrhoidal dearterialization (THD) is a minimally invasive treatment for symptomatic hemorrhoids, and outcomes with patients on anticoagulation who have undergone this procedure have not been previously reported. Here, we report our preliminary results of patients who underwent THD while on anticoagulation. Methods: During a 53-month period (February 2009-July 2015), patients with symptomatic hemorrhoids refractory to medical management who underwent surgical treatment with THD were retrospectively reviewed. The subset of patients who underwent THD while anticoagulated was compared to a cohort of patient who were not taking anticoagulation and who otherwise demonstrated normal coagulation profiles and who did not have a known predisposition to bleeding or inherited coagulopathy. The primary study endpoint was to assess postoperative bleeding in patients who were maintained on anticoagulation before and after surgery. Results: During the 53-month study period, 106 patients underwent the THD procedure for symptomatic hemorrhoids. Of these, seventy patients underwent THD without anticoagulation therapy, while 36 patients underwent THD while taking one or more oral anticoagulants. The postoperative morbidity between the two cohorts was similar, and specifically there was no statistical difference in the rate of postoperative hemorrhage (19.4 vs. 15.7 %; odds ratio 1.295, 95 % CI 0.455-3.688, p = 0.785). No patient, in either cohort, required re-intervention for any reason during the study period. Patients who underwent THD while on anticoagulation were less likely to have recurrent hemorrhoidal disease during the study's 6-month median follow-up period (2.8 vs. 7.1 %, p = 0.049). Conclusions: These preliminary data reveal that THD can be performed on anticoagulated patients without cessation of oral agents without increasing morbidity from postoperative bleeding. [ABSTRACT FROM AUTHOR]

In order to optimize the direct torque control performance of the permanent magnet synchronous motor (PMSM) system with different disturbances and uncertainties, development of an effective torque ripple reduction technique for PMSM servo drive using ant colony optimization (ACO) has been explained in this paper. ACO algorithm has been tested on a large number of samples as it produces a reduced total harmonic distortion result than other algorithms. So it is robust against motor parameter and load torque variations due to the usages of space vector modulation technique. The performance of the proposed controller is established through MATLAB and Simulink simulation with the comparisons of conventional and ANFIS controller. The simulation results explain a significant augmentation in abbreviating development time, and the system performance is also improved and it produces results very close to those of the currently best performing algorithms. [ABSTRACT FROM AUTHOR]

Background: There is an increasing, though still limited, amount of evidence describing the use of the transanal hemorrhoidal dearterialization (THD) device for the treatment of hemorrhoidal disease. This study assesses postoperative outcomes from a single surgeon experience with the THD device. Methods: From January 2009 to December 2011, 108 THD procedures were performed. With Doppler guidance, the THD device makes possible precise ligation of the branches of the superior hemorrhoidal artery. Patients were seen postoperatively at 3 weeks and 6 months. They underwent physical examination to determine whether there was recurrence of hemorrhoidal prolapse. They were asked to describe any bleeding, to rate pain using the visual analog scale, and to rate their level of satisfaction on a scale of 1-5 (with 5 = highly satisfied). A phone interview was used for follow-up at 1 year to determine the rate of recurrent prolapse. Results: Of the 108 patients who underwent THD, two were lost to follow-up and excluded. All of the remaining 106 patients completed follow-up at 3 weeks and 6 months. At 3 weeks, 92 % of patients had no pain and 88 % were highly satisfied with the procedure at 3 weeks. This increased to 92 % satisfaction at 1 year. Prolapse recurrence was 7.5 % at 6 months and 10.3 % at 1 year. Bleeding was the most common complication, but did not require re-intervention or transfusion. Conclusions: THD is a same-day procedure for the treatment of hemorrhoidal disease that is safe and effective, and offers the potential for immediate return to normal activity. [ABSTRACT FROM AUTHOR]

A new approach to expanding the suppression band and reducing the power losses in a parallel active filter by incorporating an additional corrective linear link into its structure, taking into account a delay in the interface filter, and minimizing the switching frequency of inverter power keys is developed. An algorithm of controlling the corrective link that allows increasing the performance of AF and improving the suppression of higher harmonics is proposed. [ABSTRACT FROM AUTHOR]

This paper presents a modelling of power factor correction and digital implementation of different loops of circuit such as the PI controller for voltage loop and the hysteresis controllers for current loop. Three hysteresis control techniques: fixed band, sinusoidal band and variable band are applied and have been verified by simulation. For the experimental part, all cited controllers are applied and performance tests were used to validate the results obtained through simulations using a test bench based on dSPACE DS1104. Results show that the PI controller gives a better steady-state performance under large load disturbance and variation of reference values, whereas the variable band hysteresis control in the current loop gives a low THD of the input current compared to other hysteresis controls. [ABSTRACT FROM AUTHOR]

The design of a 2.65 W, high-fidelity, filterless Class D audio amplifier in a standard 0.5 μm CMOS technology is proposed in this paper, where an architecture with multiple loop filters is utilized. This structure attenuates residual clock signals around the loop allowing very low total harmonic distortion (THD) and intermodulation distortion to be achieved in conjunction with high power supply rejection ratio (PSRR). The active area of this circuit is about 1.5 × 1.5 mm. The THD + N is <0.03 % at 1 kHz input frequency and 100 mW output power. The PSRR is −80 dB at 217 Hz and maximum output power at 10 % THD is 2.658 W. A Figure of merit is defined to estimate the excellent performance which can meet the demands of portable communication devices greatly. [ABSTRACT FROM AUTHOR]

An interleaved bridgeless buck-boost AC/DC converter is presented in this paper to achieve the characteristics of low conduction loss, a high power factor and low harmonic and ripple currents. There are only two power semiconductors in the line current path instead of the three power semiconductors in a conventional boost AC/DC converter. A buck-boost converter operated in the boundary conduction mode (BCM) is adopted to control the active switches to achieve the following characteristics: no diode reverse recovery problem, zero current switching (ZCS) turn-off of the rectifier diodes, ZCS turn-on of the power switches, and a low DC bus voltage to reduce the voltage stress of the MOSFETs in the second DC/DC converter. Interleaved pulse-width modulation (PWM) is used to control the switches such that the input and output ripple currents are reduced such that the output capacitance can be reduced. The voltage doubler topology is adopted to double the output voltage in order to extend the useable energy of the capacitor when the line voltage is off. The circuit configuration, principle operation, system analysis, and a design example are discussed and presented in detail. Finally, experiments on a 500W prototype are provided to demonstrate the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

A CMOS transconductor for wide tuning range filter application is presented. The linear transconductor is designed based on the flipped-voltage follower (FVF) circuit and can work in the weak, moderate, and strong inversion regions to maximize the transconductance tuning range. The transconductance tuning can be achieved by changing the bias current of the active resistor, and a ratio of 28 is obtained. The transconductor was evaluated by using TSMC 0.18 μm CMOS process, and the total harmonic distortion (THD) of −56 dB can be obtained by giving a 12 MHz 0.4 Vpp input swing signal. In the design, the maximum power consumption is 2 mW with the transconductance of 1.1 mS under a 1.8 V supply voltage. [ABSTRACT FROM AUTHOR]

This paper presents a high linearity MOSFET-only transconductor based on differential structures. While a precise BSIM4 transistor model is introduced through analysis, the linearity can be improved by mobility compensation techniques as the device size is scaled down in the nano-scale CMOS technology. When the compensation utilizes transistors in subthreshold region, rather than the transistors in saturation region, the value of transconductance can be maintained. The circuit is fabricated in TSMC 0.18-μm CMOS process. The measurement results show 18 dB improvement of the proposed version, and 65 dB HD3 can be achieved for a 2.1 MHz 700 mV differential input. The static power consumption under 1-V power supply voltage is 183 μW. Measurement results demonstrate the agreement with theoretical analyses. [ABSTRACT FROM AUTHOR]