Resonance Suppression Research Articles

Analysis and Suppression of Harmonic Resonance in Photovoltaic Grid-Connected Systems

In photovoltaic grid-connected systems, the interaction between grid-connected inverters and the grid may cause harmonic oscillation, which severely affects the normal operation of the system. To improve the quality of the output electrical energy, photovoltaic grid-connected systems often use LCL filters as output filters to filter out high-frequency harmonics. Taking the three-phase LCL-type photovoltaic grid-connected inverter system as an example, this paper addresses the issue of harmonic resonance. Firstly, based on the harmonic linearization method and considering the impact of the coupling compensation term on the grid-side voltage, a modular positive and negative sequence impedance modeling method is proposed, which simplifies the secondary modeling process of the converter under feedback control. Then, the stability analysis is conducted using the Nyquist criterion, revealing the mechanism of high-frequency resonance in photovoltaic grid-connected systems. Furthermore, this paper delves into the impact of changes in system parameters on impedance characteristics and system stability. The results indicate that the proportional coefficient of the internal loop current controller has a significant influence on system impedance characteristics. Additionally, this paper proposes an active damping design method that combines lead correction and capacitor current feedback to impedance-reconstruct the easily oscillating frequency band. Finally, the effectiveness of this method is verified in the simulation platform. Simulation results confirm the effectiveness of this method in suppressing harmonic resonance while maintaining rapid dynamic response.

Suppression of spurious responses near anti-resonance of TC-SAW resonators by selective thinning of SiO2

This paper discusses the generation mechanism and suppression of spurious resonances near the anti-resonance in temperature compensated surface acoustic wave devices using the SiO2/128°YX-LiNbO3 structure. Detailed field analysis is performed for the spurious resonances, and the result indicates that the spurious modes are caused by excitation and/or scattering near the electrode finger edges, and can be suppressed well by thinning of the SiO2 layer selectively in the gap region. It is also shown that most of spurious responses can be suppressed for the piston design using the Cu dots with the SiO2 selective thinning. In contrast, this selective SiO2 thinning does not work well for the piston design using the Cu stripes.

Adaptive Virtual Admittance Reshaping-Based Resonance Suppression Strategy for PMSM Drives With Small DC-Link Capacitor

Adaptive Virtual Admittance Reshaping-Based Resonance Suppression Strategy for PMSM Drives With Small DC-Link Capacitor

NMR Analysis of Extra Virgin Olive Oil of the Epirus Region of Greece with Emphasis on Selected Phenolic Compounds.

Extra virgin olive oil (EVOO) is recognized for its numerous health benefits, attributed to its rich phenolic components. NMR has emerged as a prevalent technique for precisely identifying these compounds. Among Mediterranean countries, Greece stands as the third-largest producer of olives, with the Epirus region notably advancing in olive cultivation, contributing significantly to the dynamic growth of the region. In this study, an NMR method was employed based on the acquisition of a 1H NMR spectrum along with multiple resonant suppression in order to increase the sensitivity. Using the above method, 198 samples of extra virgin olive oil, primarily sourced from the Epirus region, were analyzed, and both the qualitative and quantitative aspects of the phenolic compounds were obtained. In addition, we examined the effects of various factors such as variety, harvest month, and region origin on the phenolic compounds' concentration. The results revealed an average total phenolic content of 246 mg/kg, closely approaching the EU health claim limit of 250 mg/kg. Approximately 15% of the samples were confidently characterized as high-phenolic olive oil. The highest concentrations were observed in the Thesprotia samples, with several Lianolia varieties exceeding the total phenolic content of 400 mg/kg. Statistical tests demonstrated a significant influence of the olive variety and the month of fruit harvest on phenolic component concentration, followed by the region of origin. A very strong correlation was noted between the total phenolics content and the levels of oleocanthal and oleacein, with a correlation coefficient (r) of 0.924. Upon optimization of all factors affecting olive oil quality, the majority of the EVOOs from the Epirus region have the potential to be characterized as high in phenolic content.

Tuning and total resonant suppression of reflection in the photonic bandgap range of Bragg reflector by two-dimensional nanoparticle array

The influence of a dielectric layer with an embedded 2D array of metal nanoparticles on the spectral characteristics of a distributed Bragg reflector is theoretically studied and numerically validated. A significant dependence of the reflectivity of the hybrid structure on the location of the nanoparticle array relative to the maxima and minima of the optical field in the surface dielectric layer is demonstrated. It is found that the application of a dilute ensemble of nanoparticles (the interparticle distance is from 2 to 5 times larger than the nanoparticle size) in the region of high optical field localization makes it possible to obtain a total suppression of reflection in the photonic bandgap range of distributed Bragg reflector. Contrariwise, if the optical field is almost zero at the nanoparticle array location, its impact on the scattered light is negligible, that is, the resonant nanoparticles are masked by a highly reflective photonic structure. The target wavelength can be tuned inside the photonic bandgap range by adjusting the shape of nanoparticles and interparticle distance in the array.

Mechanical resonance suppression of the high-speed parallel robot based on fractional order disturbance observer

Considering the flexibility of the transmission shaft system, this paper presents an approach for mechanical resonance suppression of the high-speed parallel robot based on fractional order disturbance observer. First, in order to evaluate mechanical resonance, a decoupled mechatronic dynamics model is built. Based on the proposed decoupled dynamics model, the mechanical resonance under different influence factors is analyzed. Then, based on the three closed-loop control structure of servo system, a model-based parameter tuning method is adopted in the controller parameter tuning. Finally, inspired by the traditional disturbance observer, a fractional order disturbance observer is established by introducing a fractional order filter. Results show that due to the flexibility of the transmission shaft system, under the combined action of mechanical disturbance torque and electromagnetic driving torque, the joint transmission system will generate mechanical resonance phenomena. Therefore, this paper proposes a method for the mechanical resonance suppression of the high-speed parallel robot based on the fractional order disturbance observer. And the proposed method can be applied to other mechatronic device including flexible transmission shaft system.

SAW velocity reduction and spurious modes suppression on the layer structure

This paper discusses the use of the layered structure for the SAW velocity reduction. First, it is shown that the insertion of SiO2 is crucial between the piezoelectric layer and the base substrate to keep a large electromechanical coupling factor even when the SAW velocity is reduced. It is also shown that the use of a high-velocity substrate such as Si is also crucial for bringing spurious resonances much higher than the main resonance. The impact of Si orientation is also discussed. Next, suppression of transverse mode resonances and lateral leakage is studied. It is shown that the double busbar structure offers Q enhancement through good lateral energy confinement, and its combination with the piston design also gives good transverse mode suppression. Furthermore, discussions are extended to a strong spurious resonance that appears near the anti-resonance.

Use of periodic trenches in SMR-type XBAR for suppression of transverse mode resonances and lateral leakage

This paper discusses the use of periodic trenches to the top SiO2 layer of the Bragg reflector in solidly-mounted-resonator type laterally-excited-bulk-wave-resonators for the slowness manipulation to suppress both transverse mode resonances and lateral leakage. First, it is shown that the SAW slowness surface can be flattened by the application of periodic trenches, and this is owing to the coupling of the propagating SAW mode with resonances of periodic trench walls. It is also shown that flattening the SAW slowness surface enables us to suppress transverse mode resonances well. However, its impact on lateral leakage is not obvious. Then, the broadband piston mode design is applied, and its effectiveness is demonstrated for the suppression of both transverse mode resonances and lateral leakage. Deposition of a dielectric layer to the gap regions is also proposed as an alternative for leakage suppression, and it is shown that Si3N4 is appropriate as a dielectric material.

Application of an overlay for spurious suppression of multi-layered surface acoustic wave resonators with double busbar configuration

Abstract This paper discusses the suppression of a spurious resonance called the gap mode which appears when the double busbar configuration is applied to multi-layered surface acoustic wave resonators. Two kinds of overlay structures are proposed for the gap mode mitigation. First, the use of lossy ones is studied. The results indicate that the lossy overlay can effectively mitigate the gap mode response when the viscosity is adequate. The layer thickness has a negligible impact on the mitigation. Then, the discussion is extended to the application of high-acoustic-velocity materials as the overlay. The resonance frequency of the gap mode can be moved to the upper-frequency side without affecting the main resonance by simply depositing a high-velocity overlay to the gap region. Finally, the comparison and choice of overlay materials are also studied. The results point out that Si3N4 is the optimum choice for industrial use.

Use of periodically slotted SiO2 in a layered surface acoustic wave structure for transverse mode suppression

This work demonstrates the applicability of periodically slotted SiO2 (PSS) structures (PSSs) for controlling the urface acoustic wave (SAW) slowness shape and eliminating the transverse modes in layered SAW structures represented by the Incredible High Performance SAW. The use of PSS comprising SiO2 blocks and air gaps provides larger acoustic anisotropy for slowness shape manipulation. The effect of PSSs on transverse mode suppression is revealed. The slowness curves and frequency responses with different structural parameters of PSS are calculated by FEM analysis. Then, an electrode is designed for further spurious resonance suppression. A hammer-head configuration and Si3N4 overlay are applied. It is shown that higher-order transverse modes in the passband were well suppressed without reduction of the electromechanical coupling factor.

DC Active Damper Control Strategy Based on Resonance Suppression Effectiveness Evaluation Method

With the complication of the power system, features of the resonance interaction behave diversely and pose a threat to the effectiveness of the resonance suppression strategies. Existing resonance suppression strategies are usually designed for specific scenarios which are in close correlation with the impedance frequency-amplitude distribution, and their adaptability under different scenarios is hard to evaluate. In this paper, the resonance suppression domain of a DC distribution network is derived based on the node impedance variation before/after the resonance is suppressed. The derived criterion takes the admittance change of the resonance suppression strategies as variables, and the conservative/ideal suppression domain criteria are defined. On this basis, a method for evaluating the effectiveness of resonance suppression strategies is proposed, which simplifies the evaluation process and avoids a complicated matrix inverse process to each resonance suppression strategy during the system impedance calculation. Furthermore, a DC active damper control strategy based on the resonance suppression strategy evaluation is proposed, and the proposed strategy could suppress resonances under different scenarios by a targeted design of the reshaping admittance parameters. Time domain simulations with a 5-node distribution network are carried out to verify the proposed method.

Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

Effect of Blood Circulation in Veins on Resonance Suppression of the Dragonfly Wing Constructed by Numerical Method

A New Post-processing Method for Ringing Noise Suppression of Magnetic Resonance Sounding Signal

A New Post-processing Method for Ringing Noise Suppression of Magnetic Resonance Sounding Signal

Harmonic Resonance Evaluation and Suppression for Interconnected System of Traction Substation Group in Weak Power Grid

Harmonic Resonance Evaluation and Suppression for Interconnected System of Traction Substation Group in Weak Power Grid

Stability analysis and resonance suppression of multi-inverter parallel operation

Stability analysis and resonance suppression of multi-inverter parallel operation

Feature Extraction of Frequency Mapping Based Resonance Suppression in PMSM Drives with Low DC-link Capacitance and Inductance

Feature Extraction of Frequency Mapping Based Resonance Suppression in PMSM Drives with Low DC-link Capacitance and Inductance

Resonance Suppression of Multi‐Inverter Systems Based on Global Admittance Reshaping

This paper proposes an active damping control method based on converter‐side current feedback to mitigate the resonance issue in multi‐inverter grid‐connected systems caused by coupling with the grid impedance. The method aims to address the reduction in grid power quality by utilizing an active damping device without modifying the hardware and software of the grid‐connected inverters. By introducing an additional small‐capacity power electronic device in parallel, the proposed method establishes two parallel admittances at the common connection point, creating specific conduction paths for system harmonics and reshaping the overall system admittance. In parallel operation of two photovoltaic grid‐connected inverters with different capacities, the access of the inherent admittance and virtual admittance of the source damper reduces the harmonic distortion rate of the grid‐connected current from 19.81% to 2.04% and from 15.86% to 0.52%, respectively. Simulation results validate the effectiveness and correctness of the proposed strategy.

Experimental study on the wave-induced fluid resonance and suppression scheme in the narrow gap of two floating rectangular structures

An experimental study on the wave-induced gap resonance and resonant suppression scheme for two floating rectangular structures (TFRSs) is systematically presented. The instantaneous velocity fields for the present problem are measured using an enhanced underwater particle image velocimetry measurement system. Detailed experimental results have been presented to study the influences of the wave and structural parameters on the gap resonant characteristics. The resonant wave height and wave frequency were sensitive to the variation of the gap width but not very sensitive to the variation of the surface roughness on the rounded corner of TFRSs. The nonlinear effects of harmonic components on resonant free surface elevation are estimated. To analyze the vortex structures, different vortex identification methods in literature are analyzed and their merits and demerits are summarized based on a comparative analysis of the measured velocity data. The Ω-criterion vortex identification approach is then selected to evaluate the vortex intensity and capture the main vortex cores. Thanks to the adopted technique, the subsequent separation of the two quasi-symmetric vortex structures is considered to be a significant contribution to energy dissipation. The vortex shedding and dissipation modes of different TFRSs are very similar and exhibit slight variations in resonant responses. A formula of the modified Reynolds number for the gap resonance problem of TFRSs is proposed. The non-dimensional vortex strengths are nonlinearly dependent on the newly modified Reynolds number and linearly dependent on the Keulegan–Carpenter (KC) number. Finally, an optimal suppression scheme for the gap resonance problem of TFRSs is suggested.

High-Order Fully Actuated Control Approaches of Flexible Servo Systems Based on Singular Perturbation Theory

This work presents a high-order fully actuated (HOFA) control approach for flexible servo (FS) systems via singular perturbation (SP) method. The HOFA approach has the advantages of simplicity and intuition on the control design of FS systems due to its full-actuation feature, but suffers the high-order derivative problem of signals. To overcome this difficulty, this article separates the original system via the SP approach with two time-scale properties. By using the slow model, the state feedback control with dynamical compensator is designed via HOFA approach to obtain the desired tracking error dynamics. It not only avoids the high-order derivatives of signals but also improves the disturbance rejection. Based on the fast model, a simple active damping control is applied for the resonance suppression, aiming at obtaining larger control gains to further increase the control accuracy. SP theory is employed for stability analysis of the full system in the presence of uncertainties. Simulations and experiments are carried out to verify the effectiveness of the proposed approach.

Impedance Modeling and Resonance Suppression Method for Current Source VSG Under Weak Grid Conditions

Impedance Modeling and Resonance Suppression Method for Current Source VSG Under Weak Grid Conditions