Synchronous Resonance Research Articles

Application of BOPPPS Collaborative Case Teaching Method in Construction Law Classroom Instruction

This study focuses on students majoring in Engineering Management and explores the teaching model of the BOPPPS Collaborative Case Teaching Method in the Construction Law course. The research involves reforming the teaching model, introducing construction law cases, utilizing online platforms, and improving evaluation methods. The aim is to “activate” the classroom, shifting from traditional teaching to guided learning, achieving a synchronous resonance between teaching and learning. This approach intends to provide students with the time and space to enhance their ability to explore new knowledge and analyze and solve problems. It also seeks to improve students’ awareness of engineering and law, cultivate their innovative abilities, and contribute positively to enhancing the quality of talent cultivation in higher education institutions.

New perspective into the interaction behavior explore of Nano-berberine with alpha-lactalbumin in the presence of beta-lactoglobulin: Multi-spectroscopic and molecular dynamic investigations

The present study was focus on the interaction of alpha lactalbumin (α-LA) and Nano-berberine (Nano-Ber) in the absence and presence of beta lactoglobulin (β-LG) as binary and ternary systems by the exertion of different spectroscopic techniques, conductometry, β-galactosidase activity, and molecular simulation measurements. The outcomes of fluorescence quenching clarified the dominance of static quenching mechanism throughout the interaction of α-LA-Nano-Ber and (α-LA-β-LG) Nano-Ber complexes and also determined the KSV values to be (4.68±0.05) × 104 and (5.18±0.06) × 104 M−1, respectively. The measured thermodynamic parameters exhibited the participation of electrostatic forces in the binding interaction of α-LA and α-LA-β-LG complex with Nano-Ber. Moreover, the negative value of ΔG0 represents the spontaneous mode of this binding process in both systems. Synchronous fluorescence and resonance light scattering data demonstrated the impact of β-LG attendance on altering the interaction behavior of α-LA and Nano-Ber. The changes in the secondary structure of both proteins were affirmed by circular dichroism spectroscopy (CD) technique. According to the displayed β-galactosidase activity in the Michaelis-Menten plot of both binary and ternary systems, a greater Vmax refers to the stronger affinity of lactose and lactose hydrolysis that can be effective on the lactose intolerance regarding dairy products. Additionally, molecular dynamic simulations were employed to simulate the atomic-level interactions and explore the stability and conformational changes of protein-Nano Ber complexes over time. The results of these comprehensive biophysical investigations shed light on the binding characteristics, structural alterations, and dynamic behavior of Nano-Ber upon interaction with α-lactalbumin in the absence and presence of β-lactoglobulin as the binary and ternary systems. This study reveals the Nano-Ber role in the protein–protein interaction behavior and provides valuable insights into the potential applications of α-lactalbumin in the design of functional food formulations and drug delivery systems

Mitigation Sub synchronous Resonance and Improvement Low-Voltage Ride-Through Capability of Series Compensated Doubly-Fed Induction Machine Based Wind Farms by Using Bridge-Type Solid-State FCL

Mitigation Sub synchronous Resonance and Improvement Low-Voltage Ride-Through Capability of Series Compensated Doubly-Fed Induction Machine Based Wind Farms by Using Bridge-Type Solid-State FCL

Sub synchronous resonance analysis of inverter-based wind and solar farms using genetic widow optimization

Sub synchronous resonance analysis of inverter-based wind and solar farms using genetic widow optimization

Dynamical Structures Associated with High-Order and Secondary Resonances in the Spin–Orbit Problem

In our solar system, spin–orbit resonances are common under Sun–planet, planet–satellite, and binary asteroid configurations. In this work, high-order and secondary spin–orbit resonances are investigated by taking numerical and analytical approaches. Poincaré sections as well as two types of dynamical maps are produced, showing that there are complicated structures in the phase space. To understand numerical structures, we adopt the theory of perturbative treatments to formulate resonant Hamiltonian for describing spin–orbit resonances. The results show that there is an excellent agreement between analytical and numerical structures. It is concluded that the main V-shape structure arising in the parameter space (θ̇,α) is sculpted by the synchronous primary resonance, those minute structures inside the V-shape region are dominated by secondary resonances and those structures outside the V-shape region are governed by high-order resonances. Finally, the analytical approach is applied to binary asteroid systems (65803) Didymos and (4383) Suruga to reveal their phase-space structures.

Synchronous functional magnetic resonance eye imaging, video ophthalmoscopy, and eye surface imaging reveal the human brain and eye pulsation mechanisms

The eye possesses a paravascular solute transport pathway that is driven by physiological pulsations, resembling the brain glymphatic pathway. We developed synchronous multimodal imaging tools aimed at measuring the driving pulsations of the human eye, using an eye-tracking functional eye camera (FEC) compatible with magnetic resonance imaging (MRI) for measuring eye surface pulsations. Special optics enabled integration of the FEC with MRI-compatible video ophthalmoscopy (MRcVO) for simultaneous retinal imaging along with functional eye MRI imaging (fMREye) of the BOLD (blood oxygen level dependent) contrast. Upon optimizing the fMREye parameters, we measured the power of the physiological (vasomotor, respiratory, and cardiac) eye and brain pulsations by fast Fourier transform (FFT) power analysis. The human eye pulsated in all three physiological pulse bands, most prominently in the respiratory band. The FFT power means of physiological pulsation for two adjacent slices was significantly higher than in one-slice scans (RESP1 vs. RESP2; df = 5, p = 0.045). FEC and MRcVO confirmed the respiratory pulsations at the eye surface and retina. We conclude that in addition to the known cardiovascular pulsation, the human eye also has respiratory and vasomotor pulsation mechanisms, which are now amenable to study using non-invasive multimodal imaging of eye fluidics.

Black Widow Optimization Algorithm-Based Sub Synchronous Resonance Investigation with Series Compensation

The integration of wind farms into the transmission network has raised various concerns and objections. To address these challenges, the deployment of series compensators has gained significance as an effective method for enhancing the power transmission capacity of existing lines, particularly for the integration of large-scale wind farms. However, the use of series reactive compensation lines can lead to a phenomenon known as sub-synchronous resonance (SSR) in turbo generators. This SSR can cause electrical instability at sub-synchronous frequencies and potential damage to the turbine’s generator shaft, particularly during periods of peak production. As a result, the assessment of SSR through comprehensive surveys is crucial for wind power engineers to make informed decisions and ensure the safety of turbines. This study explores the potential of SSR through the utilization of the black widow optimization technique. The analysis takes into account variables such as variations in the speed of the wind, compensation spectrum, and wind velocity and examines the eigenvalue and involvement components under various operating situations. To validate our findings, electromagnetic transient simulations are conducted using the PSCAD/EMTDC software, employing the initial IEEE reference systems. This research contributes to a deeper understanding of SSR and its implications for wind energy systems.

Single-shot vector magnetic measurements using synchronous coherent population trapping resonance in a feedback compensation system

We demonstrate a real-time, single-shot vector magnetic measurement technique using synchronous coherent population trapping (SCPT) in an apparatus consisting of a small rubidium vapor cell. Vector modality of our magnetometer is enabled by designing a feedback system based on performing a peak-lock on a particularly strong 2ΩL magnetic resonance produced in the SCPT spectrum and compensating the external magnetic field via a three-axis field coil. With its current design, this magnetometer exhibits high sensitivities of approximately 155, 129, and 57pT/Hz in measuring the magnetic field vector components along the (x,y,z) axes. Sensitivities closer to the shot-noise limit can be achieved in the future by reducing the technical noise of our equipment and by employing a differential detection and polarization rotation measurement scheme in our system.

Phase-offset-based synchronous resonance identification method for blade tip timing signal

One of the most vital parts of an aero-engine is the rotor, and the working state of a rotor blade is crucial for determining the performance and safety of the engine. Blade tip timing (BTT), as an efficient and non-invasive blade vibration measurement technology, has realized the online monitoring of blade vibration. Online monitoring requires rapid and accurate extraction of blade vibration parameters. By identifying the resonance of blades, vibration parameters can be effectively extracted, such as amplitude, engine order (EO), natural frequency and other information. Through finite element simulation, it is found that when the blade is in synchronous resonance, the vibration phase measured by two probes will be different, as long as the angle between two probes has no integer multiple relation with 360°/EO. Based on this, a phase-offset resonance identification (PHRID) method was presented to identify synchronous resonance of blades. This method identifies resonance by extracting the vibration trend of probes with a special installation angle. Finally, rotor blades were tested in the experiment and compared with the strain data, and the frequency identification error within 1%. The core of this method is the trend extraction of the BTT signal of a certain probe, which greatly reduces the calculation amount and is promising to realize online monitoring. And in the case of extremely limited installation, only two probes with special angles are needed to achieve accurate extraction of resonance frequency.

Analysis and Suppression Strategy of Synchronous Frequency Resonance for Grid-Connected Converters With Power-Synchronous Control Method

The power-synchronization control (PSC) method of grid-connected converters, which is based on the active power orientation, is a promising solution for high-penetration renewable power generation systems. Unfortunately, synchronous frequency resonance (SFR) is inevitably found in PSC-controlled converters, especially when connected to inductive networks, which seriously damages the stability of the system. The relatively small equivalent resistance of the inductive network is regarded as the main cause of SFR, and a virtual resistor (VR) is usually employed to dampen this kind of oscillation. However, another important reason for SFR is the non-minimum phase effect of the loop gains, which is discussed in this paper. With considering the dynamics of the grid equivalent inductance, the small-signal model of PSC-controlled converter is established. By this, the mechanism of SFR and the non-minimum phase effect are revealed. Furthermore, a conjugate poles elimination control method based on auxiliary branches introduced into the power control loops is proposed to suppress SFR, which can also broaden the control bandwidth compared with VR method. Finally, the theoretical analysis is verified by simulations and hardware-in-loop experimental results.

A Modified VSG Control Scheme With Virtual Resistance to Enhance Both Small-Signal Stability and Transient Synchronization Stability

The existing studies show that the virtual resistance scheme has positive effects on synchronous resonance (SR) suppression but negative effects on transient synchronization stability of virtual synchronous generator (VSG). To address this contradiction, this article proposes a modified VSG control scheme. The basic idea is that the virtual active power at virtual PCC, instead of real active power, is introduced as the power feedback into the control loop. Then, the effect of virtual resistance on transient stability can be equivalent to that of grid resistance, which improves transient stability. Besides, a proportion integral controller is added at the forward loop to control the real active power to track the power reference. Compared with the existing VSG control methods, the modified VSG control scheme can well solve the conflict caused by virtual resistance between small-signal stability and transient stability. The effectiveness and superiority of the proposed method are verified by CHIL experimental results.

A three-dimensional refined numerical simulation of cross-flow induced vibration mechanism in the tube bundle

Cross-flow induced vibration causes many accidents in the nuclear steam generator tube bundle. An accurate and refined cross-flow induced vibration numerical simulation can help avoid accidents in the designed bundle for different geometries, and provide insights into flow-induced vibration mechanism. In this paper, a three-dimensional refined numerical simulation model considering the fluid viscous damping was established and validated. First, we validated the simulation of the viscous damping that structure suffered in the fluid, and studied the relationship between the fluid viscous damping and the structural spring damping in tube bundle coupling with fluid. The results showed that fluid viscous damping coefficient and the structural spring damping coefficient can be directly added to equal the total damping coefficient in the coupling system between the tube bundle and fluid. Then, a three-dimensional simulation based on SST-SAS (the Transition SST combined with the Scale Adaptive Simulations (SAS) turbulence model) was used to study flow-induced vibration for the literature experiment tube bundle. Simulation of flow-induced vibration had the same mass-damping parameters with the literature experiment. The vibration amplitude trend and spectra of the simulation were basically consistent with that of the experiment. Simulation accurately captured the onset of the vortex-induced resonance and the transition from the vortex-induced resonance to the fluidelastic instability. And the different mechanisms and their transition were analyzed. Specially, the flow field and structure analysis showed that the local vortex-induced resonance of the front-row tubes caused the synchronous resonance of the whole tube bundle.

Experimental Investigation: Vibration Measurement of a Rotating Blade with Digital Image Correlation and Blade Tip-Timing.

High cycle fatigue has been known as an important form of aeroengine blade failure. This study aims to achieve a method of investigation for a rotating blade vibration measurement, combining the two non-contact optical techniques of digital image correlation (DIC) and blade tip-timing (BTT). Dynamic parameters of a thin-blade were obtained on a stationary vibration platform with stereo-DIC system. Meanwhile, the finite element analysis (FEA) of this thin-blade was performed within different rotating speeds. Then, the set of thin-blades was mounted in a simulated compressor test rig equipped with BTT and a wireless strain gauge (SG) system. A rotor speed sweep experiment was carried out and the blade synchronous resonance parameters were extracted. Results show that the displacement mode shapes match well between DIC and FEA, and that MAC values of the first six order modes are over than 0.88. The predicting strain from the FE model and SG agreed to within 32.41% in the worst case, and the predicting strain from the DIC model corresponds to 28.53% in the worst case. This is an effective non-contact, high-precision full-field deformation measurement method that is worth exploring for structural design and dynamic strain assessment of vibrating components.

Sub-synchronous resonance in wind energy integrated grid – problem and mitigation techniques – a review

<p>When wind energy conversion systems (WECS) are integrated with the Grid system then there are power quality issues arises. The fluctuation in the wind power delivery to the grid demands robust control for a better power quality. Therefore, voltage and frequency stability due to integration of wind to the grid is the primary concern to improve the overall grid integration capability for WECS. This paper reviews the power quality issues in the power grid due to introduction of WECS. The WECS integration with the grid introduces dynamic issues that include sub-synchronous resonance (SSR), low voltage ride through (LVRT), frequency support from wind generation, synchronization, and transients. Also, it focusses on the sub synchronous resonance introduced due to introduction of doubly-fed induction generator (DFIG) wind turbines to the transmission lines with capacitive seriescompensation. The review of various power quality issues and methods used by the researcher’s mitigations are discussed and detailed further research perspective.</p>

A novel method for identification of synchronous resonance frequency of blades based on random arrangement of tip-timing probes

Blade tip-timing (BTT) signal suffers from the undersampling feature, which causes the high-frequency information to be aliased to the low-frequency band, especially the aliasing problem of the synchronous resonance frequency more serious. In order to realize the frequency identification of undersampled signals in synchronous resonance, a novel multiscale cyclic-reverse optimized arrangement (MC-ROA) method based on the random arrangement of tip-timing probes is proposed in this paper. Firstly, a sparse model for frequency recovery is built based on the link between the known undersampled signals and the unknown original signals in the frequency domain, and the subspace pursuit (SP) algorithm of compressive sensing (CS) is used for frequency recovery. Then, under the random arrangement of probes, the number of ideal probes is adjusted at multiple scales and the datum probes are selected cyclically to obtain multiple sets of solutions. Finally, the target frequency weights are used to overcome the limitations of the restricted isometry property (RIP) of the parameterized compression matrix to determine the optimal recovery frequency. The BTT experiments are given to verify the effectiveness of the proposed method.

Characteristics analysis of blade tip timing signals in synchronous resonance and frequency recovery based on subspace pursuit algorithm

Long-term high cycle fatigue vibration will lead to the reduction of life of the blade. Blade Tip Timing (BTT) technology is a research hotspot in the non-contact measurement of blades. Due to the limitation of the number of sensors, BTT signals present serious undersampled conditions. Identifying the frequency of blade vibration through the analysis of undersampled signals is the key problem of the current BTT technology. A sub-Nyquist technique, called multi-coset sampling (MCS), which is suitable for the BTT sampling model can be applied. In this paper, the characteristics of BTT signals under blade synchronous resonance are described and the deficiency of this feature in the recovery process using the orthogonal matching pursuit (OMP) algorithm is found. Based on the problem, the subspace pursuit (SP) algorithm adapted to this feature is proposed. The validity of the algorithm is verified by the blade rotation experiment. The advantage of this algorithm is that the synchronous resonance frequency of the blades can be recovered with a higher probability, which provides a new idea for the development of BTT technology.

A Proportional Investigation among UPFC and DPFC in a Grid Associated Photovoltaic Organization

Abstract: In this paper a proportional investigation between Unified Power Flow Controller (UPFC) and Distributed Power Flow Controller (DPFC) in a grid incorporated photovoltaic system is performed. A grid connected solar generation scheme with boost converter and voltage source inverter (VSI) is taken as the key model. Due to power quality issues like power oscillations, harmonic distortions, voltage sags and swells, the grid side system has to be absolutely monitored and restricted. One way to mitigate these power quality troubles is by using reactive elements like shunt/series reactor and shunt/series capacitor. The drawback on using these reactive elements is sub synchronous resonance phenomenon. Gratitude to FACTS equipment, which emerged out as power conditioning units and helps to feed power with required standards and free from power quality issues. Among them, the contemporary FACTS devices are Controller Distributed Power Flow (DPFC) and Unified Power Flow Controller (UPFC). Though the aims of both the devices are same but their working principles are different. In this paper the effect of adding a DPFC and UPFC to a solar PV generation system is analysed. A detailed working principle and operation of both the devices were presented. At last, MATLAB/SIMULINK environment is used to evaluate the performances of abovementioned devices.

Dynamic-Decoupled Active Damping Control Method for Improving Current Transient Behavior of LCL-Equipped High-Speed PMSMs

In this article, a novel dynamic-decoupled active damping current controller is proposed for an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -equipped high-speed permanent magnet synchronous machine. Compared with the conventional stationary current-control method for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -type system, the proposed method is established in the synchronous rotating frame for improving the current transient performance. When taking the controller into the synchronous coordinate, there are two following challenges: first, the synchronous resonance frequency varying in a wide range because of the synchronous coordinate transformation, and second, eliminating the coupling between the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${dq}$</tex-math></inline-formula> coordinate. To address these issues, an improved synchronous capacitor-current-feedback active damping method is designed based on arbitrary pole assignment and is significantly effective for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> resonance within the Nyquist frequency. Moreover, a novel dynamic-decoupled motor-current controller is proposed to eliminate the coupling between the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${dq}$</tex-math></inline-formula> -axis motor current. The gain selection method is discussed to acquire sufficient phase margin and gain margin. Finally, the effectiveness of the proposed method is verified by driving the tested motor to 72 kr/min.

Power Flow and Power Quality Enhancement by TCSC using five different Novel Methods.

The demand of electricity is continuously increasing due to increase in population and urbanisation. Due to lack of generation and transmission facilities there is over exploitation of present resources. The existing transmission lines are overloaded which make the system prone to stability problems. In the proposed work the power flow is increased in the existing system after using FACTS device using five different methods. They are firing by TCR pulse generator, using control subsystem based on RS Flip Flop, using Synchronised 6 pulse generator, using Thyristor -6 pulse generator with PLL, and pulse generator block of MATLAB.TCSC is used to control the dynamic power flow and also to enhance the power quality of the system. The power quality of the system is polluted due to use of common harmonic loads like computers, motor drives, arc and induction furnaces, battery charges, rectifiers, induction heating equipment. So, power electronics-based device TCSC is used in the proposed work. increases the efficiency of the line and improve the stability and security of the system. The active power at the receiving end is enhanced using the above different methods and the various results of power flow enhancement and THD analysis is shown. The THD analysis of the system is done in the present work using all the different methods. There provide other benefits to the system like damping power system oscillations, mitigating sub synchronous resonance, providing voltage support, improving transient stability.

Impedance modelling and grid integration stability evaluation of three‐phase virtual synchronous generator

Virtual synchronous generator (VSG), which can behave with analogous characteristics as the conventional synchronous generator (SG) and provide voltage and inertia/damping support, is universally regarded as a grid-friendly interface. Here, the comprehensive sequence-impedance model of the VSG is developed by using the harmonic linearization method. To improve the accuracy of impedance model, the influences of the reactive power loop (RPL) and mirror frequency effect (MFE) are discussed and evaluated for the first time. Three different impedance models of the VSG (conventional, considering RPL, and considering both MFE and RPL) are derived and compared in detail. Besides, the synchronous frequency resonance (SFR) issue and grid-interactive oscillation risk of the VSG are also investigated. The results indicate that the VSG may suffer from power oscillation when the integral coefficient of RPL is too large, but has excellent robustness and stability when connected to weak grid. This feature makes it more appealing in weak grid integration. Finally, the validity of the theoretical analysis is verified by simulations and experiments.