High Harmonic Levels Research Articles

Time response of active sound control with a harmonic acoustic pneumatic source: simulations and experimental results

Active noise control is studied as a solution to reduce the blade passing frequency tonal noise of turbofans during landing and takeoff. A promising alternative to loudspeakers used as secondary sources is the Harmonic Acoustic Pneumatic Source (HAPS), that has been designed to generate a high harmonic noise level controllable in amplitude and phase using slow time varying signals. The objective is to design, characterize and optimize an active control system capable of following a time varying primary noise. A configuration with a loudspeaker acting as a primary source, a HAPS mounted laterally on a rectangular duct and an error microphone is considered. A first single-input-single-output controller for the case of plane wave control has been tested and allowed a convergence time of about 2 seconds to reach 20 dB attenuation of the acoustic pressure at 440 Hz. The results are consistent with simulations of the system and the convergence time can be explained by the dynamics of the HAPS. This study is a first step towards the objective of performing multimodal active noise control in duct with multiple sources in presence of flow.

Power Loss and Temperature Distribution in Coil of PFC Inductor with Air Gap for Multimode Operation

Power converters inherently display non-linear load characteristics, resulting in a high level of mains harmonics, and hence the necessity of implementing Power Factor Correction (PFC). Active PFC circuitry typically comprises an inductor and a power switch to control and alter the input current so that it matches, in shape and phase, the input voltage. This modelling of the waveforms can be performed by means of distinct conduction modes of the PFC inductor. The digital controller implemented in the constructed and investigated boost-type PFC converter can be programmed to operate in discontinuous conduction mode (DCM), continuous conduction mode (CCM), or a combination of the two. The individual modes of operation, via distinct PFC inductor current waveforms, impact the overall efficiency of power conversion and, by extension, temperature distribution in the magnetic component. This paper investigates how the examined conduction modes bear on distinct power-loss mechanisms present in the PFC inductor, including high-frequency eddy-current-generating phenomena, and the fringing effect in particular. As demonstrated herein, the DCM operation, for the set output power level, exhibits exacerbated power dissipation in the winding of the inductor due to the somewhat increased RSM value of the current and the intensified fringing magnetic flux at an air gap. The latter assertion will undergo further, more quantitatively focused research. Finally, the construction of the coil was optimised to reduce power loss by diminishing eddy-current mechanisms.

Waveform-to-Waveform End-to-End Learning Framework in a Seamless Fiber-Terahertz Integrated Communication System

Seamless fiber-terahertz integrated communication has emerged as a promising technology in the special field of 6G, including mobile fronthaul and wireless bridges. Electronic terahertz communication systems have the advantages of high-level integration, small form factors, and potentially low costs, but their drawbacks are their small bandwidths and high harmonic interference levels. In this paper, an end-to-end learning-based waveform-to-waveform automatic equalization framework (W2WAEF) is proposed to overcome the above shortcomings in a seamless fiber-terahertz integrated communication system. An attention-based three-tributary heterogeneous neural network (ATTH) is designed to simulate the channel model of a seamless fiber-wireless communication system, taking fiber optics, optical-to-electrical conversion, and electrogenerated terahertz waves into account. With the proposed method, a data rate of 80.78 Gbps is experimentally demonstrated for discrete multitone modulation (DMT) signals over 5 km of fiber and 1 m of 209-GHz terahertz signals under a 20% soft decision-forward error correction (SD-FEC) threshold of 2.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−2</sup> . Compared with an approach without preprocessing, a receiver sensitivity gain exceeding 1.3 dB is successfully achieved at a data rate of 60 Gbps. The proposed method is a promising scheme for meeting the high speed and low-cost demands of future seamless fiber-terahertz integrated communication systems.

Analiza kvaliteta električne energije na satnom nivou kod priključenja elektrana na obnovljive izvore energije

Analyses necessary for the new power plant connection contain the following power quality analyses carriedout using the simulation model: Estimation of the emission level of the voltage waveform asymmetry at the point of connection, estimation of the high harmonic components at the connection point and estimation of the emission level of long-term and shortterm flicker. Limits for the previously mentioned parameters have been defined in the National Grid Code (at the national level) or in the international standards. According to the international standards, the limit is considered violated if the duration of the parameter value violation exceeds 5% of the monitored period. Conventional approach of power quality analysis through software tool assumes only analysis for the most critical regime: when the short-circuit power at the point of connection is the lowest and the new power plant produces maximum active power. Based on this approach mitigation measures for improving power quality supply are sometimes suggested to the plant investor. In should be noted that Renewable Energy Sources (RES) do not have maximum output power during the whole year, and consequently, power quality deterioration is much less than in the critical regime observed in the simulations. For power quality simulation purposes, technical sheets of the equipment contain high harmonic levels for the full operation range are used from which usually the worst (highest) harmonic injections are considered for modelling RES as a harmonic source. In this paper, the results of power quality analyses for the RES connection using hourly resolution data for the one-year period based on DPL (DIgSILENT Programming Language) in DIgSILENT PowerFactory software package will be presented. This approach gives the duration of the limit violation, and consequently, more reliable results in comparison with the results of the conventional approach.

Development of an improved automatic control algorithm for combined RCB burners and carbonaceous material injectors of a flexible modular furnace

The control algorithm for combined ceramic regenerative burners (Regenerative Ceramic Burner, RCB) and carbon-containing material injectors of a flexible modular arc steel-smelting furnace DSP-1 operating at one of the domestic metallurgical enterprises is considered. It was revealed that in the concept adopted in production, the decision to switch the RCB burner from the burner mode to the oxygen lance mode, as well as to turn on the carbon-containing material injectors, is made directly by the operator of the furnace plant based on a set of empirical features characteristic of one or another technological stage of melting. In this regard, an improved control algorithm for RCB burners and carbon-containing material injectors has been developed and proposed for implementation, which will ensure the adoption of the above-mentioned decisions in automatic mode. This algorithm is based on the analysis of the slag coefficient, the value of which directly depends on the level of higher harmonics in the spectrum of electric arc current signals, as well as physical processes occurring inside the furnace bath. The implementation of the proposed algorithm enables to achieve the most timely adaptation of operating modes of combined burners and carbon-containing material injectors, which in turn will increase the overall energy efficiency of the steelmaking complex as a result of an increase in the total thermal efficiency of electric arcs and the optimal operating mode of the burners.This work was supported financially by the Ministry of Science and Higher Education of&nbsp;the Russian Federation (Project No. FZRU-2020-0011).

RECURRENT USE OF A PERCEPTRON FOR SIGNAL STRUCTURAL ANALYSIS

The paper is devoted to the use of an artificial neural network (ANN) of direct propagation (multilayer perceptron) for signal processing in electrical engineering and electric power industry. It is proposed to use such simple neural networks instead of ANN with a more complex structure (convolutional, recurrent), but within the framework of a sequential recurrent algorithm. This allows checking and controlling the quality of signal processing at each stage of calculations. The proposed algorithm is tested on the example of structural analysis of a signal with nonlinear distortions in a sliding time window. It is shown that the amplitude, frequency and phase of an industrial frequency signal with a high level of harmonics and an aperiodic component can be isolated with an accuracy of units of percent for a time not exceeding units of milliseconds. To increase the accuracy at each step of the calculations, traditional methods can be used, in addition to the ANN: averaging, median smoothing, etc.

Analisis dan Performa Disain Tujuh Step Multilevel Inverter

The Seven Step multilevel inverter has 3 H – Bridge switching circuits which are designed from transistor and IGBT semiconductor circuits. The performance of the switches is regulated by the ignition unit which consists of pulses of frequency with a certain ignition angle. This pulse pulse determines the output voltage form of the H-Bridge multilevel inverter circuit. The output voltage form is a square pulse. There are seven step output voltage levels that are close to a sinusoidal shape, but still contain high levels of harmonics. This large Total Harmonic Distortion (THD) can be overcome by increasing the number of levels or steps in the output voltage by adding an H-Bridge strand to the next level. The modeling of this 7 step multilevel inverter circuit is designed using Matlab Simulink Tools.

Impact assessment of grid tied rooftop PV systems on LV distribution network

Due to the high demand for electricity in the world today and the need to reduce carbon footprint, the power system is undergoing a profound change and this change is paving way for renewable electricity generation into the traditional grid, making the conventional network become smarter. The convention which has been in existence over several decades has changed; thus, consumers of electricity have now become prosumers; generating and feeding electricity into the low voltage network. Despite the benefits of prosuming, some researchers say their presence create stability, reliability and power quality (over and under-voltages, and high harmonic distortion levels) problems which in effect lead to overloading of transformers and feeders, extreme line losses, and failure in network protection exceeding the limits in the low voltage grid.The objective of this paper is to evaluate the effect of rooftop PV generations on distribution losses (power losses) and network voltage profile (voltage regulation on LV network) in a typical traditional grid setup. The study employs an empirical analysis of the power system, forward/backward sweep based on BIBC and BCBV matrices and python simulation to arrive at its conclusion under two different scenarios, nine different loading conditions and six PV (from 1kWp to 6kWp) injections.The results obtained show that a grid connected with rooftop PV systems have the potential of reducing distribution losses substantially and also do not violate standardized voltage limits. The net power loss recorded on the network with PV injections from 1kWp to 6kWp were in the range of 1.1kW–88.9kW at poor power factors and 0.7kW and 89.1kW at improved power factors, respectively. The variation in the voltage profile ranges between 0.97pu and 1.05pu for both the conventional and prosumer grids.

A Cascaded Controller for a Grid-Tied Photovoltaic System With Three-Phase Half-Bridge Interleaved Buck Shunt Active Power Filter: Hybrid Control Strategy and Fuzzy Logic Approach

This paper focuses on the control development of a grid-tied photovoltaic system coupled with a shunt active power filter. The considered power system includes a PV panel, a single-capacitor three half-bridge interleaved buck converter connected to a three-phase power grid and a nonlinear load. This study aims to accomplish simultaneously three objectives: i) to ensure a high compensation level of current harmonics and reactive power consumed by the nonlinear load in order to perform power factor correction at the grid side; ii) to extract the maximum power from the PV panel regardless the climatic conditions; iii) to regulate the dc bus capacitor voltage to its reference provided by the MPPT controller. To this end, a controller using a two-loop cascade strategy is designed. First, the inner loop is developed with the hybrid automaton approach to formulate the switching control signals with the aim of guaranteeing a unitary power factor. Second, the outer loop is designed using fuzzy logic control to ensure the regulation of the photovoltaic voltage, while the perturb and observe algorithm is employed to perform maximum power point tracking. Finally, the system with the developed control scheme is simulated using MATLAB/SimPowerSystems environment. The obtained results confirm that the proposed controller is able to achieve the previous objectives under varying environmental conditions.

Development and implementation of a voltage harmonic elimination method for the single-phase inverter operating with nonlinear load

Single-phase inverters are widely used in power conversion systems. When operating with linear loads, these inverters produce regulated quasi-sinusoidal output voltages. When feeding nonlinear loads, they absorb non-sinusoidal (distorted) currents and the inverter's output voltage deteriorates - it contains high levels of harmonics. This paper presents a method to reduce the harmonics in the output voltage. The control strategy is based on selective harmonic elimination - the method eliminates some of the low order harmonics of the output voltage. The method uses stationary reference frame voltage and current controllers. The voltage controller regulates the fundamental and eliminates certain harmonics using a modulation-demodulation technique. In the paper, the 3rd, 5th and 7th harmonics are eliminated. However, the scheme can be expanded to eliminate more higher-order harmonics. It is shown that the control proposed, significantly reduces the total harmonic distortion of the inverter's output voltage, from 5.8% to 1.64% (at full load).

Design of an universal source for semi-automatic ac welding and induction heating

This paper proposes a circuit solution and a power source control algorithm for semi-automatic AC welding with improved energy and weight-size characteristics. A distinctive feature of the designed source is the absence of an input rectifier: welding is carried out with a high-frequency alternating current. That has made it possible to significantly reduce power losses in the source, as well as provide the possibility of implementing induction heating by connecting an inductor to the source output. Another distinctive feature of the designed source is an increased power factor and a reduced level of higher harmonics of the current consumed. The power factor of the described source reaches 0.94 against 0.5÷0.7 for sources equipped with a conventional rectifier with capacitive smoothing. The designed source's composition includes a power supply system for the wire feed drive with speed stabilization due to positive feedback on the motor current. That has made it possible to ensure the stable operation of the drive in a wide range of speeds. A model has also been developed of a flux wire welding torch containing a feed drive and a coil with a wire (up to 100 mm in diameter), placed, in order to reduce the size, in the handle of the torch. In addition to the welding function, the source makes it possible to solve the tasks related to induction heating and/or hardening of small parts; to that end, a compact inductor is connected to its output. Tests of the source showed the feasibility of the proposed ideas and circuit solutions. The dimensions of the source are 190×107×65 mm; weight, 1.4 kg; output current, up to 120 A. The proposed technical solution enables the construction of small-sized, lightweight, universal, easy-to-use power supplies for semi-automatic welding with the option of induction heating

ANALISA PENGARUH PENGOPERASIAN FILTER AKTIF TERHADAP RUGI-RUGI DAYA DAN DERATING TRAFO PADA SISTEM KELISTRIKAN DI RS BIMC NUSA DUA

Nonlinear loads are harmonic current sources for utilities. High harmonic levels greatly increase the loss of electrical energy. The quality of electric power is determined by the parameters of power losses that appear in the electrical system of BIMC Nusa Dua Hospital due to harmonic distortion. In this study, THD analysis was carried out based on the results of measurements and simulations according to the IEEE 519-2014 standard, analysis of power loss due to THD current due to non-linear loads, and analysis of power loss after installation was carried out. Active filter, calculation of the working capacity of the transformer before and after installing an active filter.

Transnational by Default: Online Child Sexual Abuse Respects No Borders

Abstract Combatting child sexual abuse on the internet requires a high level of harmonisation of both substantive and procedural laws, as online child sexual abuse is transnational by default: while the transnational nature of child sexual abuse material used to be the exception before the advent of the internet, it is now the rule. In order to prosecute and investigate online child sexual abuse across country borders, states rely heavily on extraterritorial jurisdiction clauses as well as informal and formal law enforcement collaboration channels. This paper analyses existing channels in the opsc, Budapest Convention and Lanzarote Convention, particularly against the background of the recently published crc Committee Guidelines regarding the implementation of the Optional Protocol to the Convention on the Rights of the Child on the sale of children, child prostitution and child pornography (crc/c/156), and provides for concrete guidance on how to ensure that the best interests of the child in the prosecution and investigation of transnational crimes such as online child sexual abuse is the primary consideration.

Power Quality and Performance Analysis of Grid-Connected Solar PV System Based on Recent Grid Integration Requirements

The electrical energy demand is steadily growing, and hence, the integration of photovoltaic system to the distribution networks is also dramatically increasing though it has a significant effect on the network’s power quality. The purpose of this paper is to analyze the impact of solar PV integration on the power quality of distribution networks. The study is conducted using ETAP software, taking one of the radial distribution networks available in Bahir Dar city during the peak of connected loads which has the least voltage profile. Furthermore, the optimal location of the PV in the network is done using particle swarm optimization. Accordingly, the appropriate location of the PV system is determined to be the farthest end bus (bus 34). Also, the impact in terms of voltage and current harmonic distortion on the distribution feeder network is comparatively discussed by comparing the distribution system parameters with different penetration levels of solar PV system. The simulation results obtained demonstrate that high harmonic distortion level is injected correspondingly as the penetration capacity of PV system increased which indicates that the solar PV system should be integrating only up to a maximum possible capacity the network can carry. The integration of the PV system beyond this maximum penetration level causes production of high harmonic distortion which adversely affects the system performance. At the maximum penetration level which allows the acceptable harmonic distortion limit, the total voltage harmonic distortion and current demand distortion are found to be 4.97% and 14.98%, respectively.

Mitigation of Harmonics and Unbalanced Voltage Disturbance Compensation by MSVPWM Based- DVR in the Distribution Net

Recent power distribution networks comprise abundant sensitive loads, which extremely impact the power quality of source in electrical power networks. Voltage dip, voltage rise, imbalanced voltage, line notching and distortion of harmonics are problems of power quality frequently take place. Pre-disturbance voltage compensation strategy and phase-locked-loop (PLL) based dq- space vector control are presented to improve a Dynamic Voltage Restorer (DVR), which restore the magnitude of voltage disturbance and displacement of phase angle to prior of voltage disturbance. 3-phase Multilevel strategy of Space Vector Pulse Width Modulation (MSVPWM) based- Multilevel Diode Clamped Converter (MDCC) is proposed as switching pulse signals employed low frequency, which creates high levels of voltage and fewer harmonics in the output waveform in comparison to 2-level SVPWM based- DVR. 3-level SVPWM based- DVR under balanced and imbalanced distortion voltage disturbances included sags and swells injected appreciated quantities of voltage, thereby attained ideal sinusoidal waveform with lower Total Harmonic Distortion THD% compared to 2-level SVPWM based- DVR. Furthermore, real and imaginary powers balanced effectively at sensitive load during various distortion voltage disturbance conditions via presented work. The proposed simulation model of multi-level SVPWM based- DVR is implemented by dedicating the software system of MATLAB/SIMULINK. The results of simulation exhibit the effectiveness and efficiency of the presented work under different distortion voltage disturbance conditions.

New Design Approach of a “2.4 GHz” Slotted Rectangular Patch Antenna with a Wideband Harmonic Suppression

The designing of an antenna with a wideband harmonic suppression will lead to enhance the overall antenna performance efficiency as well as neglecting electromagnetic noises. A “defective ground superimposing” or a Y-slot construct confederated with a ring hopefully meets an effective approach that is exploited in removing high level of harmonics in the design process. A “2.4 GHz” rectangular U-slot microstrip patch antenna with an active antenna radiators and harmonic suppression grid has been presented. The paper focuses on the geometrical of active integration antennas to achieve efficient filtering and easy attenuation of unwanted harmonics. Further, an embedded empirical antenna with a high-order harmonic suppression has been suggested. This is followed by a “complementary opening recoiled construct cell”. The proposed approach was developed to control the antenna harmonics at center frequency of " $$2.4 \;{\text{GHz}}$$ ." The simulation sketches show that the reflection coefficient of multiple harmonics had an effective suppression up to 3.2 dB without any effect on the resonant frequency. The radiation patterns at high suppression levels of harmonics are within the range (13.92–15.2 dB) for both E-plane and H-plane. Further, the designed antenna bandwidth at the resonant frequency is $$\left( {85\;{\text{MHz}}} \right)$$ . Finally, the proposed antenna with $${\text{DGS}}$$ had return losses and antenna gain of $$\left( { - 23.15 \;{\text{dB}};\;8.25\;{\text{dB}}} \right),$$ respectively.

ANALYSIS OF GEOMAGNETICALLY INDUCED CURRENT IN POWER GRID DURING GEOMAGNETIC STORM

Solar storms are event that has a big range of averse outcome on technological system, power grid specifically. During extreme geomagnetic storms a GIC begin to travel between long transmission lines or conducting constructions. The possibility of solar storms features an approximately linear relation with the sun spot activity level that fluctuates in eleven years cycle. This paper could be threat examination of GIC in power system and describe the causes, the implications, each on power system apparatus level and on power system level. When GIC flow in neutral of transformer winding it start to causes the Half-cycle core saturation and produce high level of harmonics can sense bad fault situation to protective relays and mis-operation of circuit breakers. Also this paper mentioned potential risk mitigation ways

Territorialidad de los derechos de autor y mercado único digital

Un rasgo distintivo de la UE es el nivel particularmente elevado de armonización de los regímenes nacionales de derecho de autor, lo que puede facilitar el desarrollo de mecanismos específicos para sortear la actual fragmentación del mercado interior al margen de la creación de títulos unitarios. El alcance de la competencia judicial internacional condiciona la adopción de medidas judiciales para la tutela de derechos de autor en diversos Estados miembros, pero tal posibilidad requiere la aplicación de tantas legislaciones como Estados. En algunos instrumentos recientes se observa una tendencia renovada a recurrir al criterio del país de origen para superar obstáculos derivados de los regímenes nacionales de derecho de autor. En este contexto, se valoran las aportaciones del Reglamento (UE) 2017/1128 y las Directivas (UE) 2019/789 y 2019/790 en lo relativo a la regulación de las actividades transfronterizas en el marco del mercado único digital.

Analysis of the level of higher harmonics in the sugar supply system

Analysis of the level of higher harmonics in the sugar supply system

Effect of AC-voltage harmonics on oil impregnated paper in transformer bushings

With the global trend to establish smart distributed-generation grids, the level of AC-voltage harmonics is significantly increasing due to power electronic converters interfacing renewable energy sources with the grid. Such harmonics will not only degrade the power quality and increase the losses in the electricity grids but will also have a severe impact on oil impregnated paper (OIP) in power transformer bushings. While much attention has been given to investigate the deterioration of OIP under thermal and electrical stresses, the impact of voltage harmonics on the OIP structure is still uncertain and calls for more investigations. Therefore, this paper is aimed at investigating the variations of the multilevel structure of an OIP aged under high levels of AC-voltage harmonics. In this context, degree of polymerization of the aged OIP is measured to reveal the changes of OIP secondary structure. Also, X-ray diffraction, deuteration treatment and Fourier transform infra-red spectroscopy are conducted to analyze the changes of the OIP aggregate structure during the aging process. Further experiments are performed to investigate the variation of the microscopic appearance, thermal behavior and dielectric properties, including scanning electronic microscopy, thermal gravity analysis, differential scanning calorimetry and frequency domain spectroscopy. This investigation on the variation of the multilevel structure of aged OIP not only promotes further understanding to the aging behavior and mechanism of OIP under AC-voltage harmonics, but also proposes crystallinity and accessibility as two new effective aging indicators for the OIP structure.