Harmonic Source Research Articles

High-harmonic generation from a subwavelength dielectric resonator.

Higher-order optical harmonics entered the realm of nanostructured solids being observed recently in optical gratings and metasurfaces with a subwavelength thickness. Structuring materials at the subwavelength scale allows us toresonantly enhance the efficiency of nonlinear processes and reduce the size of high-harmonic sources. We report the observation of up to a seventh harmonic generated from a single subwavelength resonator made of AlGaAs material. This process is enabled by careful engineering of the resonator geometry for supporting an optical mode associated with a quasi-bound state in the continuum in the mid-infrared spectral range at around λ=3.7 μm pump wavelength. The resonator volume measures ~0.1 λ3. The resonant modes are excited with an azimuthally polarized tightly focused beam. We evaluate the contributions of perturbative and nonperturbative nonlinearities to the harmonic generation process. Our work proves the possibility to miniaturize solid-state sources of high harmonics to the subwavelength volumes.

Harmonics Signal Feature Extraction Techniques: A Review

Harmonic estimation is essential for mitigating or suppressing harmonic distortions in power systems. The most important idea is that spectrum analysis, waveform estimation, harmonic source classification, source location, the determination of harmonic source contributions, data clustering, and filter-based harmonic elimination capacity are also considered. The feature extraction method is a fundamental component of the optimization that improves the effectiveness of the Harmonic Mitigation method. In this study, techniques to extract fundamental frequencies and harmonics in the frequency domain, the time domain, and the spatial domain include 67 literature reviews and an overall assessment. The combinations of signal processing with artificial intelligence (AI) techniques are also reviewed and evaluated in this study. The benefit of the feature extraction methods is that the analysis extracts the powerful basic information of the feedback signals from the sensors with the most redundancy, ensuring the highest efficiency for the next sampling process of algorithms. This study provides an overview of the fundamental frequency and harmonic extraction methods of recent years, an analysis, and a presentation of their advantages and limitations.

High-speed and wide-field nanoscale table-top ptychographic EUV imaging and beam characterization with a sCMOS detector.

We present high-speed and wide-field EUV ptychography at 13.5 nm wavelength using a table-top high-order harmonic source. Compared to previous measurements, the total measurement time is significantly reduced by up to a factor of five by employing a scientific complementary metal oxide semiconductor (sCMOS) detector that is combined with an optimized multilayer mirror configuration. The fast frame rate of the sCMOS detector enables wide-field imaging with a field of view of 100 µm × 100 µm with an imaging speed of 4.6 Mpix/h. Furthermore, fast EUV wavefront characterization is employed using a combination of the sCMOS detector with orthogonal probe relaxation.

Calculation of resonant modes in electric networks in case of sources of higher harmonics

Subject of research: resonant modes in electrical networks 35/6/0.4 kV of oil producing enterprises.
 Purpose of research: calculation of frequencies at which the occurrence of resonant modes is possible, determination of the multiplicity of overvoltages in the nodes of the electrical network.
 Object of research: distribution electrical networks 35/6 kV, groups of non-linear electrical receivers 0.4 kV, which are sources of harmonic distortion.
 Main results of research: a method for calculating resonant modes in the presence of sources of higher harmonics is presented. The frequencies at which the occurrence of resonances is possible are determined; for each voltage class, the multiplicity of arising overvoltages is determined. Physical measurements of non-sinusoidality levels were carried out using certified equipment. Based on a comparison of the calculation results and the actual level of higher harmonics in the electrical network, a technically sound decision is made to install filter-compensating devices to suppress higher harmonics and prevent an emergency.

Interactions Between Harmonic Sources from Industrial Grid and Electric Vehicles

Interactions Between Harmonic Sources from Industrial Grid and Electric Vehicles

An artificial neural network based harmonic distortions estimator for grid- connected power converter-based applications

Grid-connected solar Photovoltaic (PV) systems are predicted to cause significant harmonic distortions in today’s power networks due to the increase utilization of power conversion systems widely recognized as harmonic sources. Estimating the actual harmonic emissions of a certain harmonic source can be a challenging task, especially with multiple harmonic sources connected, changes in the system’s characteristic impedance, and the intermittent nature of renewable resources. A method based on an Artificial Neural Network (ANN) system including the location-specific data is proposed in this paper to estimate the actual harmonic distortions of a solar PV inverter. A simple power system is modelled and simulated for different cases to train the ANN system and improve its prediction performance. The method is validated in the IEEE 34-bus test feeder with established harmonic sources, and it has estimated the individual harmonic components with a maximum error of less than 10% and a maximum median of 5.4%.

A novel Ethernet based processing system for remote source harmonic detection

This work is carried out to objectively establish a new method to detect harmonics and measure the total harmonic distortion (THD) in a remote source, such as a high voltage transformer. The proposed approach utilized embedded design techniques to construct an embedded processor system with Ethernet intellectual property core to acquire data from a remote harmonics source. The designed system has several notable merits, namely, it is portable that can be applied in the work field, and it avoids workers from being subject to a hazard high voltage shock as well as its simplicity and high accuracy. The harmonics detection and analysis are achieved by inserting a microcontroller system near the high voltage transformer to acquire the necessary data and transmit it to a remote embedded processor system that is used to detect and analyze the harmonics. The microcontroller and the processor systems are connected by a wide-area network (WAN) through Ethernet and transmission control protocol/internet protocol (TCP/IP) protocols. The processor system is accommodated to perform 128 points fast Fourier transform for harmonics detection. Matlab simulations are used to validate the results. It is found that the results match very accurately the simulation results with an error of less than 0.02%.

Study on harmonic metering characteristics of Rogowski coil current transformer

This paper introduces the harmonic requirements of a power system transformer and the principle of the Rogowski coil electronic current transformer, summarizes the simple and practical methods for harmonic measurement of the Rogowski coil electronic current transformer, and conducts harmonic measurement of the electronic current transformer through high-precision harmonic source and standard current transformer and transformer calibrator. The results show that this method has strong applicability and simple operation, which greatly enriches the harmonic measurement methods.

A novel optimization strategy for line loss reduction in distribution networks with large penetration of distributed generation

With the large penetration of power electronic devices in distribution networks, power quality problems such as line loss and harmonics have become the main factors affecting the access of distributed generation (DG). At present, the research on DG integration, such as the optimization of the DG capacity using particle swarm optimization algorithm and ant colony algorithm, is mainly focused on the traditional distribution network. In contrast, the research on the power electronic distribution networks, which include a large number of harmonic sources, is not sufficient. This paper presents a novel optimization method for connecting DG to power electronic distribution network to reduce line loss. Firstly, based on the frequency domain model of the distribution network, this paper establishes the harmonic model of distribution network components, including generators, transformers, lines, harmonic sources and non-harmonic sources. Then the location and capacity of DG are optimized using genetic algorithm with network loss reduction as a target and voltage and harmonic as constraints. Finally, the power electronic distribution network is modelled based on the IEEE 34 - node standard model. The obtained results confirmed that the optimization model with harmonic constraints can effectively reduce the line loss by 108.26 kW and the line loss rate by 4.67 % using single DG. Also, when using the double DG, the line loss and the line loss rate are decreased by 118.53 kW and 5.14 %, respectively. In addition, the optimization effect of dual DG is better than that of single DG without considering the cost.

Multiple harmonic sources identification including inverter‐based distributed generations using empirical Fourier decomposition

AbstractThis paper proposes an intelligent approach based on the empirical Fourier decomposition (EFD) to identify harmonic sources at the point of common coupling (PCC) when different inverter‐based distributed generations (DGs) like microturbine (MT), battery energy storage system (BESS), photovoltaic (PV), superconducting magnetic energy storage (SMES), wind turbine with a permanent magnet synchronous generator (PMSG), and doubly‐fed induction generator (DFIG) wind turbine are presented. In order to decrease memory storage and computational burden, strife feature selection is used. Applying just voltage signals consumes less processing time and decreases measurement devices. Moreover, the whale optimization algorithm (WOA) as the optimizer of the parameters of the support vector machine (SVM) classifier is used. Consequently, the results from the proposed method can be helpful for both engineers and researchers to plan and develop a better strategy to mitigate harmonic distortion.

Characterisation of engineered defects in extreme ultraviolet mirror substrates using lab-scale extreme ultraviolet reflection ptychography

Ptychography is a lensless imaging technique that is aberration-free and capable of imaging both the amplitude and the phase of radiation reflected or transmitted from an object using iterative algorithms. Working with extreme ultraviolet (EUV) light, ptychography can provide better resolution than conventional optical microscopy and deeper penetration than scanning electron microscope. As a compact lab-scale EUV light sources, high harmonic generation meets the high coherence requirement of ptychography and gives more flexibilities in both budget and experimental time compared to synchrotrons. The ability to measure phase makes reflection-mode ptychography a good choice for characterising both the surface topography and the internal structural changes in EUV multilayer mirrors. This paper describes the use of reflection-mode ptychography with a lab-scale high harmonic generation based EUV light source to perform quantitative measurement of the amplitude and phase reflection from EUV multilayer mirrors with engineered substrate defects. Using EUV light at 29.6nm from a tabletop high harmonic generation light source, a lateral resolution down to ∼88nm and a phase resolution of 0.08rad (equivalent to topographic height variation of 0.27nm) are achieved. The effect of surface distortion and roughness on EUV reflectivity is compared to topographic properties of the mirror defects measured using both atomic force microscopy and scanning transmission electron microscopy. Modelling of reflection properties from multilayer mirrors is used to predict the potential of a combination of on-resonance, actinic ptychographic imaging at 13.5nm and atomic force microscopy for characterising the changes in multilayered structures.

MODELING AND ANALYZING THE EFFECT OF CONNECTION TO THE NETWORK OF A HARMONIC SOURCE HAVING VARIOUS TOTAL HARMONIC DISTORTION FACTORS ON LOAD SIGNAL WAVEFORMS

This article examines the effect of a network connected source of harmonics having a total harmonic distortion factor varying from 5% to 15% on load voltage and current waveforms. When a source of higher harmonics is connected to the network, both in the network and in the load, the effective values of voltage and current increase, that can negatively affect the cable line insulation, accelerating its destruction and aging.
 To analyze the consequences of a power quality deterioration, a 20 kV network was simulated, consisting of a 20 kV symmetrical generator, an XRUHAKXS-20(1x120/50) power cable line 20 km long, a step-down transformer 20/0.4 kV with a power of 2 MVA, with windings connected in delta-star, and a three-phase symmetrical load.
 The values of the currents flowing through the cable conductor, obtained as the result of simulation were used to calculate the voltage drop between the cable conductor and its shield. Results obtained show that the connection of a harmonic distortion source to a network leads to a magnification of a current flowing through the cable conductor by more than 2%. The model proposed in the article can be used further for a more detailed study of solar photovoltaic plants connection to the grid.
 One of the biggest problems regarding solar power plants is that its electricity generation is intermittent. Thus, future efforts should be focused on modeling and studying the higher harmonics generation during switching on and off of the solar photovoltaic plants.

Perencanaan Desain Single Tuned Passive Filter Harmonisa Pada AC Microgrid Turbin Tenaga Angin

A microgrid usually consists of small-scale of thermal generation sources and other distributed energy resources (DER) such as photovoltaic, wind power, and fuel cells to serve its loads. In this paper microgirid AC system using wind turbines. Microgrid AC systems use an inverter which is a source of harmonics for need to convert to AC system Load . And the system will also get the source of harmonics when the system is connected to the non-linear load. wind turbines can generate harmonics also. So that it can degrade the quality of the power of the system. In addition the power factor, and voltage system is not good. So thesystem mitigate solution is using a passive filter tuned to the affected bus. The simulation results show that the design singgle tune passive filters can be effective and have a good performance in mitigating microgrid system

Interval Harmonic Power Flow Algorithm Based on Relative Distance Measure

In the harmonic power flow calculation of the power grid, the indeterminacy of new energy generation, the volatility and intermittency of nonlinear load will lead to the uncertainty of the injected harmonic current. In order to deal with the uncertainty information in the power grid, relative distance measurement (RDM) is used instead of point values to describe the uncertainty of distributed generations(DGs) output and state variables. In this paper, the RDM harmonic source model is built to solve the interval harmonic power flow. Through a typical 33-node distribution network calculation example, it is testified that the RDM Power flow algorithm has sufficient completeness and low conservatism compared with the traditional interval algorithm and Monte Carlo method.

To the study of the vibration in an acoustic medium with coating excited by a concentrated harmonic source

When monitoring dangerous geodynamic processes, it is topical to study wave fields on the surface of geological structures and, since on the scale of the Earth’s structure, lithospheric plates can be considered as coatings of small thickness, a plate is accepted as the simplest model of an extended lithospheric one. The paper considers the problem of the plate oscillations on the surface of an acoustic layer, excited by the effect of a concentrated harmonic source located in an acoustic medium. The solution is built using an integral approach well developed for similar problems arising in geophysics, seismoacoustics and ecology. Integral representations of the amplitude values for the stress on the lower boundary of the coating and the surface displacements of the structure under consideration are obtained.

22-W average power high pulse energy multipass-cell-based post-compression in the green spectral range.

A gas-filled multipass-cell-based post-compression of 515 nm wavelength second-harmonic pulses of an Yb:fiber laser from 240 fs to 15.7 fs is presented. The system delivers 0.44 mJ of pulse energy, 22.4 W of average power at 50.8 kHz with an overall efficiency of more than 40%. These results display the capabilities of multipass-cell-based post-compression schemes to move from the well-established near infrared spectral region to the undeveloped visible regime, allowing for high efficiencies in conjunction with energetic ultrashort pulses at high repetition rates. The unique combination of parameters in the green spectral range offers an immense potential for future developments of high photon flux higher-order harmonic sources.

Efficient low-density grating setup for monochromatization of XUV ultrafast light sources.

Ultrafast light sources have become an indispensable tool to access and understand transient phenomenon in material science. However, a simple and easy-to-implement method for harmonic selection, with high transmission efficiency and pulse duration conservation, is still a challenge. Here we showcase and compare two approaches for selecting the desired harmonic from a high harmonic generation source while achieving the above goals. The first approach is the combination of extreme ultraviolet spherical mirrors with transmission filters and the second approach uses a normal-incidence spherical grating. Both solutions target time- and angle-resolved photoemission spectroscopy with photon energies in the 10-20 eV range but are relevant for other experimental techniques as well. The two approaches for harmonic selection are characterized in terms of focusing quality, photon flux, and temporal broadening. It is demonstrated that a focusing grating is able to provide much higher transmission as compared to the mirror+filter approach (3.3 times higher for 10.8 eV and 12.9 times higher for 18.1 eV), with only a slight temporal broadening (6.8% increase) and a somewhat larger spot size (∼30% increase). Overall, our study establishes an experimental perspective on the trade-off between a single grating normal incidence monochromator design and the use of filters. As such, it provides a basis for selecting the most appropriate approach in various fields where an easy-to-implement harmonic selection from high harmonic generation is needed.

Harmonic source localization method for the port distribution system based on the stagewise regularized orthogonal matching pursuit algorithm

The application of power electronic technology which is widely used in large mechanical equipment of ports causes inevitable harmonic pollution issues. Due to the small capacity of the port power system, harmonic interference will bring huge security risks to its normal operation. Therefore, it is necessary to carry out the effective localization of the harmonic sources in the grid. In this paper, a harmonic source localization method based on the stagewise regularized orthogonal matching pursuit (SROMP) is proposed by improving the orthogonal matching pursuit (OMP) in a compressed sensing theory. It can achieve accurate localization of harmonic sources only through measurement information analysis, which is significantly superior to traditional methods. First, according to the grid topology and line parameters, a system equation is constructed that takes the node harmonic voltage as the measurement variable and the harmonic current injected to the node as the state variable. Next, the equation is solved to obtain the harmonic current value injected to each node. The result can reflect the harmonic injection situation of each node, so as to determine the position of each harmonic source. In order to test the localization effect of the algorithm under different measurement configurations, the SROMP method is compared with other algorithms in considerable simulation experiments on the improved IEEE-33 model, which verifies the stability and accuracy of the proposed algorithm.

Active Sound Power Attenuation with a Ring of Harmonic Acoustic Pneumatic Sources fOr Destructive Interference (RHAPSODI) and near field in-duct microphones

Much research has been conducted to investigate active noise control of turbofans with loudspeakers as noise cancellation sources. However, the required power consumption, fragility, and weight and volume penalty make them unsuitable for engine nacelle applications. An alternative source technology, developed at Sherbrooke, is a harmonic acoustic pneumatic source (HAPS). They are mounted on a ring to perform multimodal active noise control in duct by destructive interference of primary noise (RHAPSODI). A dedicated MIMO harmonic control strategy based on complex envelopes is required to control the RHAPSODI with in-duct microphones located at a very close distance from it or with external in-duct microphones located 1 meter away from the duct mouth. During a training phase, active radiated power minimization is performed with the external microphones for different modal components of the primary harmonic noise. The optimal HAPS control and the optimal signals from the in-duct microphones are then used to tune the specific MIMO controller with a field compensation matrix close to the in-duct microphone signals. A typical result shows that RHAPSODI using 5 in-duct microphones and 5 HAPS can provide high attenuation of radiated sound power (22 dB-SPL, 1 kHz, primary sound power 130 dB).

The dependence of transformer sound power measurement accuracy on microphone configurations in the anechoic chamber.

The paper is aimed at investigating the number and location of microphones required to accurately calculate the sound power level of a harmonic noise source. The measurement procedure performed is based on the IEC standard for the determination of transformer sound power level. The current procedure defines numerous measurement points around the tested transformer. Reducing the number of measurement points could significantly speed up the measurement procedure when a transformer is tested during the manufacturing process. Within the research work, estimations on the number and location of measurement points are identified to accurately calculate sound power level. The approach is tested and validated using specially developed software in LabView, that allows inclusion or exclusion of measurement points from the sound power level calculations. To prevent harmonic wave interference, acoustic wave reflections and background noise, the measurement procedure took place in the anechoic chamber.