Maximum Total Harmonic Distortion Research Articles

Detailed Controller Synthesis and Laboratory Verification of a Matching-Controlled Grid-Forming Inverter for Microgrid Applications

Grid-forming inverters are the essential components in the effort to integrate renewable energy resources into stand-alone power systems and microgrids. Performance of these inverters directly depends on their control parameters embodied in the controller. Even the most conscientiously designed controller will exhibit suboptimal performance upon implementation due to the presence of parasitic elements in the existing hardware. Hence, the controller has to be tuned and optimized. In the present article, the process of implementation, laboratory verification, and tuning of a matching-controlled grid-forming inverter is presented. In order to assess the efficiency of the grid-forming controller, its operation has been tested and analyzed in blackstart, steady state, and transient operation. For this purpose, a systematic sensitivity analysis has been conducted and the control parameters have been tuned in laboratory tests. The laboratory results verify proper operation of a 7 kW grid-forming inverter in all three test scenarios. After applying the proposed method on the tested grid-forming inverter in steady state operation, total harmonic distortion (THD) of the output voltage is less than 0.5% for its practical loading range (maximum THD is less than 1% in no-load condition). The system is able to blackstart and supply the loads. Finally, the studied grid-forming inverter is stable in the presence of severe step load changes and disturbances, i.e., voltage overshoot is managed well and compensated for with a low settling time using this approach.

A Crossover Optimization-Based Control for Making Strides in BLDC Motor Utilizing Renewable Sources

This study explores the eco-friendly and versatile applications of renewable energy sources, with a focus on solar modules adaptable to varying conditions. The objective is to minimize switching loss and enhance Total Harmonic Distortion (THD) outcomes. Solar energy harnessed from PV panels is utilized to power a BLDC motor, employing two methods to amplify PV panel output. In the initial approach, Maximum Power Point Tracking (MPPT) is implemented using a hybrid PSO and cuckoo-searches (HPSO_CSO) technique. The second method integrates an AC load through DC-DC converters connected to a BLDC motor and a multilayer inverter. Comparative analyses encompassing maximum power, stator current, THD, and duty cycle are conducted for both the conventional PSO-based BLDC and the proposed HPSO_CSO BLDC systems. The findings reveal that the suggested HPSO_CSO converter with BLDC motor outperforms existing methods, exhibiting the most favorable outcomes. The entire system is simulated using the SIMULINK model, with MATLAB 2021a employed for implementation. The proposed HCSO-PSO-MPPT approach achieves an impressive THD of just 1.08%, signifying superior power conversion performance in contrast to existing techniques.

Simultaneous allocation of renewable energy sources and custom power quality devices in electrical distribution networks using artificial rabbits optimization

Abstract This study suggests an optimal renewable energy source (RES) allocation and distribution-static synchronous compensator (D-STATCOM) and passive power filters (PPFs) for an electrical distribution network (EDN) to improve its performance and power quality (PQ). First, the latest metaheuristic artificial rabbits optimization (ARO) is used to locate and size solar photovoltaic (PV), wind turbine (WT) and D-STATCOM units. In the second stage, ratings of single-tuned PPFs and D-STATCOMs at the RESs are determined, considering non-linear loads in the network. The multi-objective function reduces power loss, improves the voltage stability index (VSI) and limits total harmonic distortion. Simulations using the IEEE 33-bus EDN compared the ARO results with those of previous studies. In the first scenario, ideally integrated D-STATCOMs, PVs and WTs reduced losses by 34.79%, 64.74% and 94.15%, respectively. VSI increases from 0.6965 to 0.7749, 0.8804 and 0.967. The optimal WT integration of the first scenario outperformed the PVs and D-STATCOMs. The second step optimizes the WTs and PQ devices for non-linear loads. WTs and D-STATCOMs reduce the maximum total harmonic distortion of the voltage waveform by 5.21% with non-linear loads to 3.23%, while WTs and PPFs reduce it to 4.39%. These scenarios demonstrate how WTs and D-STATCOMs can improve network performance and PQ. The computational efficiency of ARO is compared to that of the pathfinder algorithm, future search algorithm, butterfly optimization algorithm and coyote optimization algorithm. ARO speeds up convergence and improves solution quality and comprehension.

Application of Deep Learning Gated Recurrent Unit in Hybrid Shunt Active Power Filter for Power Quality Enhancement

This research work aims at providing power quality improvement for the nonlinear load to improve the system performance indices by eliminating maximum total harmonic distortion (THD) and reducing neutral wire current. The idea is to integrate a shunt hybrid active power filter (SHAPF) with the system using machine learning control techniques. The system proposed has been evaluated under an artificial neural network (ANN), gated recurrent unit, and long short-term memory for the optimization of the SHAPF. The method is based on the detection of harmonic presence in the power system by testing and comparison of traditional pq0 theory and deep learning neural networks. The results obtained through the proposed methodology meet all the suggested international standards of THD. The results also satisfy the current removal from the neutral wire and deal efficiently with minor DC voltage variations occurring in the voltage-regulating current. The proposed algorithms have been evaluated on the performance indices of accuracy and computational complexities, which show effective results in terms of 99% accuracy and computational complexities. deep learning-based findings are compared based on their root-mean-square error (RMSE) and loss function. The proposed system can be applied for domestic and industrial load conditions in a four-wire three-phase power distribution system for harmonic mitigation.

Towards Realization of a Low-Voltage Class-AB VCII with High Current Drive Capability

In this paper, the implementation of a low-voltage class AB second generation voltage conveyor (VCII) with high current drive capability is presented. Simple realization and good overall performance are the main features of the proposed circuit. Proper solutions and techniques were used to achieve high signal swing and high linearity at Y, X and Z ports of VCII as well as low-voltage operation. The operation of the proposed VCII was verified through SPICE simulations based on TSMC 0.18 µm CMOS technology parameters and a supply voltage of ±0.9 V. The small signal impedance values were 973 Ω, 120 kΩ and 217 Ω at Y, X and Z ports, respectively. The maximum current at the X port was ±10 mA with maximum total harmonic distortion (THD) of 2.4% at a frequency of 1 MHz. Considering a bias current (IB) of 29 µA and output current at the X port (IX) of 10 mA, the current drive capability (IX/IB) of about 345 was achieved at the X port. The voltage swing at the Z port was (−0.4, 0.4) V. The THD value at the Z port for an input signal with 0.8 V peak-to-peak value and frequency of 1 MHz was 3.9%. The total power consumption was 0.393 µW.

GaN-HEMT Based Very-High-Frequency AC Power Supply for Electrosurgery.

To power electrosurgery, a very-high-frequency AC inverter (VHFI) is required. In this paper, a full-bridge based VHFI is proposed to enable electrosurgery. Its high-frequency output generating mechanism and the high order filter design are explained. To check the feasibility of the proposed VHFI, a 300 W Gallium Nitride High Electron Mobility Transistors (GaN HEMT) based experimental setup with 390 kHz output frequency, has been designed and implemented. Experimental efficiency and total harmonic distortion (THD) results are graphed for pure cutting mode. It turns out that maximum THD is less than 2.5% for the proposed VHFI. Further, recurring and burst experiment results are provided for blend cutting mode and coagulation mode, respectively. The experiment results show that the proposed VHFI has extreme fast-responding time for both blend cutting and coagulation mode, and crest factor is about 21 for coagulation mode. All experiment results together validate the feasibility of the proposed VHFI and also verify its capability of supporting different load values under different clinical modes.

Compact CMOS Analog Multiplier Free of Voltage Reference Generators

This work presents a CMOS four quadrant analog multiplier architecture for application as the synapse element in analog cellular neural networks. For this reason, the circuit has voltage-mode inputs and a current-mode output and the chief design targets are compactness and low energy consumption. A signal application method is proposed that avoids voltage reference generators, which contributes to reduce sensitivity to supply voltage variation. Performance analysis through simulation has been accomplished for a design in CMOS 130 nm technology with 163 µm2 total active area. The circuit features ±50 mV input voltage range, 86 µW static power and ‑28.4 dB maximum total harmonic distortion. A simple technique for manual calibration is also presented.

Leakage Current Reduction in Single-Phase Grid-Connected Inverters—A Review

The rise in renewable energy has increased the use of DC/AC converters, which transform the direct current to alternating current. These devices, generally called inverters, are mainly used as an interface between clean energy and the grid. It is estimated that 21% of the global electricity generation capacity from renewable sources is supplied by photovoltaic systems. In these systems, a transformer to ensure grid isolation is used. Nevertheless, the transformer makes the system expensive, heavy, bulky and reduces its efficiency. Therefore, transformerless schemes are used to eliminate the mentioned disadvantages. One of the main drawbacks of transformerless topologies is the presence of a leakage current between the physical earth of the grid and the parasitic capacitances of the photovoltaic module terminals. The leakage current depends on the value of the parasitic capacitances of the panel and the common-mode voltage. At the same time, the common-mode voltage depends on the modulation strategy used. Therefore, by the manipulation of the modulation technique, is accomplished a decrease in the leakage current. However, the connection standards for photovoltaic inverters establish a maximum total harmonic distortion of 5%. In this paper an analysis of the common-mode voltage and its influence on the value of the leakage current is described. The main topologies and strategies used to reduce the leakage current in transformerless schemes are summarized, highlighting advantages and disadvantages and establishing points of comparison with similar topologies. A comparative table with the most important aspects of each converter is shown based on number of components, modes of operation, type of modulation strategy used, and the leakage current value obtained. It is important to mention that analyzed topologies present a variation of the leakage current between 0 to 180 mA. Finally, the trends, problems, and researches on transformerless grid-connected PV systems are discussed.

A 42-GHz TIA in 28-nm CMOS With Less Than 1.8% THD for Optical Coherent Receivers

This letter shows a fully differential linear transimpedance amplifier designed for the emerging coherent optical communications for high data rate transmissions. The purpose of this letter is to present a possible solution in 28-nm CMOS technology instead of the most frequently used BiCMOS. The idea is to take advantage of the linearity of CMOS to partially offset its inherently lower transconductance over current ratio, which typically limits the bandwidth. The proposed TIA presents a −3-dB bandwidth equal to 42 GHz and its transimpedance gain can be programmable from 78 to 36 dB $\Omega $ with four variable gain stages. At maximum gain, the measured average input noise is equal to 18 pA/√Hz whereas the maximum total harmonic distortion for an output voltage swing of 500-mV peak-to-peak differential is always lower than 1.8% over the entire gain range. The complete transimpedance amplifier including the bias and dc offset cancellation circuits consumes 319 mW from a 2.4-V supply voltage.

REALIZATION OF TOTAL HARMONIC DISTORTION MEASUREMENT OF ACOUSTIC SOURCE SIGNAL SYSTEM FOR FREQUENCY OF 125 HZ AND 1000 HZ

<p>The measurement of total harmonic distortion (THD) of an acoustic source signal system has carried out in Laboratory Acoustics and Vibration, Sub-directorate of National Measurement Standards for Acoustics and Vibration - BSN. The aim of this research is, therefore, to measure and analize the THD values that produced by the system that consists of a signal generator, a power amplifier, and a passive loudspeaker with fundamental frequencies of 125 Hz and 1000 Hz. This measurement should be implemented because it has never been performed in this laboratory. Moreover, this system always be used for either calibration or measurement of acoustical instruments such as sound level meter and noise dosimeter. The method used to measure THD is a free field method using a full anechoic chamber with narrow band analysis. Measurand to determine THD is sound pressure level (SPL) with output of loudspeaker are 94 dB, 104 dB, and 114 dB. From result of measurement was found THD value of fundamental frequencies of 125 Hz and 1000 Hz. For the former frequency, the maximum THD was found at SPL of 94 dB where its value was 1,86 %. Meanwhile the later, the maximum value of THD was 1,94 % also at SPL 94 of dB. The results of this measurement can be used into uncertainty budget for either calibration or testing of acoustical instruments, and also support for validation of calibration of noise dosimeter based on percentage of noise exposure dose using acoustic comparison coupler that still under research and development in this year.</p>

GA-based approach for optimal placement and sizing of passive power filters to reduce harmonics in distorted radial distribution systems

This paper presents a Genetic Algorithm-based approach for optimal placement and sizing of passive power filters to mitigate harmonics in radial distribution systems with linear and nonlinear loads. The problem is formulated as a nonlinear multi-objective optimisation problem with equality and inequality constraints. For solving this problem, the Genetic Algorithm’s performances are analysed and evaluated using the standard IEEE 18- and 33-bus test systems. The optimal solutions are obtained based on the following four optimisation criteria: (1) minimisation of the maximum level of the total harmonic distortion in voltage, (2) minimisation of the initial investment costs of the filters, (3) minimisation of total active power losses in distribution lines and (4) a simultaneous minimisation of the maximum total harmonic distortion in voltage, initial investment costs of filters and total active power losses. The system harmonic levels are estimated using the Decoupled Harmonic Power Flow algorithm. Simulation results, obtained using the proposed Genetic Algorithm-based approach, are compared with those obtained using other optimisation algorithms and verified using the Harmonic Analysis module of the Electrical Transient Analysis Program. It is shown that the Genetic Algorithm-based approach provides effective, robust and high-quality solutions.

Minimizing harmonic distortion impact cause by CS using meta heuristic technique

Non-linear load in the distribution system has caused negative impact to its power quality especially on harmonic distortion. Charging Station (CS) is a non-linear load that widely promoted with the aim to support the continuous usage of Electric Vehicle (EV). This research is focusing on optimal placement and sizing of multiple passive filter to mitigate harmonic distortion due to CS usage at distribution system. There are 6 units of CS which being placed in low voltage buses which indirectly will inject harmonic to the system during charging. Power system harmonic flow, passive filter, CS, battery and the analysis will be model in MATLAB. Multi-objective function which are weight summation approach (WSA) and Pareto Front are used to assist meta heuristic technique which is Modified Lightning Search Algorithm (MLSA) to identify optimum location and sizing of passive filter based on improvement on propose five parameters. From the result, the optimal placements and sizing of passive filter able to reduce the maximum Total Harmonic Distortion (THD) for voltage, current and apparent losses respectively. Therefore, the propose method is suitable to reduce harmonic distortion as well as apparent losses at distribution system with present of CS.

Minimization of harmonic distortion impact due to large‐scale fast charging station using Modified Lightning Search Algorithm and Pareto‐Fuzzy synergistic approach

The increased number of nonlinear loads in the distribution system has caused a significant impact on its power quality in the form of higher harmonic distortion. The fast charging station (FCS) is an example of a powerful nonlinear load that is currently being widely promoted with the aim of supporting the continuous usage of electric vehicles (EV). The most common and cheapest method to minimize harmonic impact is through the use of a passive filter. This paper presents an optimal sizing and placement of a passive filter design based on the numbers of FCS installed in the distribution system. The MATLAB/m‐file platform is used to model the power system harmonic flow, passive filter, and FCS. The control strategy used to minimize the total harmonic distortion (THD) due to the large number of FCS is presented based on the selection of optimal location and the size of passive filters that will provide minimum THD and apparent power losses to the overall distribution system. A Modified Lightning Search Algorithm (MLSA) technique is applied with the aim of identifying the optimal solution. The Pareto‐Fuzzy technique is used to obtain a better solution among nondominated solutions. From the result, the optimal placements and sizes of passive filter will be able to reduce the maximum THD and also the total losses in the distribution system, which is equipped with 17 FCS units. This study is useful as a guide for grid owners to control the impact of large‐scale FCS deployment in the distribution system. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Low power current sources for bioimpedance measurements: a comparison between Howland and OTA-based CMOS circuits

Abstract Multifrequency Electrical Bioimpedance (MEB) has been widely used as a non-invasive technique for characterizing tissues. Most MEB systems use wideband current sources for injecting current and instrumentation amplifiers for measuring the resultant potential difference. To be viable current sources should have intrinsically high output impedance for a very wide frequency range. Most contemporary current sources in MEB systems are based on the Howland circuit. The objective of this work is to compare the Mirrored Modified Howland Current Source (MMHCS) with three Operational Transconductance Amplifier (OTA) based voltage controlled current sources (i.e., class-A, class-AB and current conveyor). The results show that both current conveyor and class-AB OTA-based current sources have a wider output current frequency response and an output impedance of 226% larger than the MMHCS circuit at 1 MHz. The presented class-AB OTA circuit has a power consumption of 4.6 mW whereas current conveyor consumed 1.6 mW. However, the MMHCS circuit had a maximum total harmonic distortion of 0.5% over the input voltage from -0.5 to +0.5 V. The OTA-based current sources are going to be integrated in a semiconductor process. The results might be useful for cell impedance measurements and for very low power bioimpedance applications.

Flicker Evaluation of the SeaGen Tidal Power Plant

This paper presents the power quality evaluation of a 1.2-MW tidal power plant. The results show that the unit works well and that the power quality impact is moderate to low and for future units which most likely will have more turbines, the power quality impact will be very low. The wind turbine power quality standard IEC 61400-21 was used in this investigation, and was adequate; however, regarding the connecting transients, there could be a need for a specific standard. It is found that the power level is well controlled at higher water speeds; the maximum 10-min power is found to be 1.21 MW. The maximum 2-s value is found to be 1.46 MW and the maximum 60-s value is found to be 1.30 MW. The reactive power exchange with the grid is negligible; at full load, the power factor is 0.99. The flicker coefficient is between 1 and 5, depending on the grid impedance angle. Finally, it can be said that the maximum total harmonic distortion (THD) for the voltages is found to be 1.2% and for the current 0.65% during operation with the complete power plant.

Generalised design methodology of second-order filters for voltage-source inverters with space-vector modulation

The paper presents a systematised and generalised methodology of second-order output filter for inverters that synthetise sinusoidal voltage waveforms through space-vector pulse-width modulation (PWM). The objective of this methodology is to determine the largest natural frequency of the filter that ensures specification of the maximum total harmonic distortion (THD) admissible in the output voltages of the PWM inverter. The proposed methodology is discussed in detail, including the description of the steps needed to derive the design procedure for different topologies of voltage inverters, and the procedure for obtaining the design curves. To illustrate the use of the proposed methodology, detailed design procedures are given for single-phase, three-phase three-wire and three-phase four-wire filter topologies. Finally, examples are presented which include experimental results demonstrating the validity of the proposed design methodology.

Metodologia de projeto de filtros de segunda ordem para inversores de tensão com modulação PWM digital

Este artigo apresenta uma metodologia sistematizada de projeto de filtros de saída de segunda ordem para inversores que sintetizam tensões senoidais através de modulação por largura de pulso (PWM) digital. O propósito desta metodologia é o de determinar os parâmetros do filtro que assegure a especificação da máxima taxa de distorção harmônica total (THD) admissível nas tensões de saída do inversor PWM, para cargas lineares e não-lineares. A metodologia proposta é discutida em detalhes, incluindo a descrição das etapas necessárias para a derivação do procedimento de projeto para diferentes topologias de inversores de tensão e o procedimento para obtenção das curvas necessárias para o projeto. Finalizando, são apresentados alguns exemplos de projeto para topologias de inversores monofásicos e trifásicos com saída a três fios e a quatro fios. Resultados experimentais são apresentados para demonstrar a validade da metodologia de projeto proposta.

High-quality output PWM AC voltage regulator based on Cuk converter

This paper describes the design of an AC–AC converter capable of generating a high-quality output. It is based on the Cuk configuration, with the transistors replaced by bidirectional switches. Since there are no transformers in the configuration, the converter lends itself to a compact and lightweight implementation. The design process is aimed at using, as much as possible, the tools and devices already developed for DC–DC applications. This approach greatly simplifies the design and implementation of the converter. An integrated circuit, developed for DC–DC applications, is used to control the converter. Both the set-point and the feedback signal are rectified in order to fit the input range of the controller. Tests performed show that the output exhibits a maximum total harmonic distortion of 3% (resistive load). The efficiency is slightly higher than 89%, and the average output regulation is 0.3%. The converter is capable of correcting voltage sags down to 60% and voltage swells up to 30%, with the output returning to its nominal value within one mains cycle. The results show that the converter is suitable for energizing information-processing equipment.

Solutions for CMOS current amplifiers with high-drive output stages

Design guidelines for CMOS current amplifiers with a high-drive capability are discussed in detail, paying special attention to the implementation of output stages with improved linearity performance. As a design example, two different current amplifiers were realized in a 1.2-/spl mu/m process and experimentally tested. Both circuits used a 5-V power supply and dissipated 5.5 and 4 mW, respectively. The open-loop gain was found to be 90 and 100 dB and the gain-bandwidth product was 8 and 10 MHz. The two amplifiers provide bipolar output currents as high as 15 and 7 mA, with a maximum total harmonic distortion of around -54 dB, using a quiescent current in the output branches of only 200 /spl mu/A.

Design and characterization of a system for exposure of cultured cells to extremely low frequency electric and magnetic fields over a wide range of field strengths.

A system is described that is capable of producing extremely low frequency (ELF) magnetic fields for relatively short-term exposure of cultured mammalian cells. The system utilizes a ferromagnetic core to contain and direct the magnetic field of a 1,000 turn solenoidal coil and can produce a range of flux densities and induced electric fields much higher than those produced by Helmholtz coils. The system can generate magnetic fields from the microtesla (microT) range up to 0.14 T with induced electric field strengths on the order of 1.0 V/m. The induced electric field can be accurately varied by changing the sample chamber configuration without changing the exposure magnetic field. This gives the system the ability to separate the bioeffects of magnetic and induced electric fields. In the frequency range of 4-100 Hz and magnetic flux density range of 0.005-0.14 T, the maximum total harmonic distortion of the induced electric field is typically less than 1.0%. The temperature of the samples is held constant to within 0.4 degrees C by constant perfusion of warmed culture medium through the sample chamber.