Resonance Spikes Research Articles

Resonance Suppression Method Based on Hybrid Damping Linear Active Disturbance Rejection Control for Multi-Parallel Converters

The parallel operation of multiple LCL-type converters will result in a deviation of the resonant frequency and resonance phenomena. The occurrence of harmonic resonance can cause problems such as an increase in harmonic voltage and current. This can lead to the malfunction of relay protection and automatic devices, causing damage to system equipment. In severe cases, it can cause accidents and threaten the safe operation of the power system. A hybrid damping active disturbance rejection control (HD-ADRC) method is proposed in this paper to suppress the harmonic resonance of parallel LCL-type converters. First, a third-order linear disturbance rejection controller (LADRC) including the linear extended-state observer and the error-feedback control rate is designed based on LCL-type converter model analysis. The proposed method considers the resonance couplings caused by both internal and external disturbances as the total disturbance, thus improving the anti-disturbance capabilities as well as the operational stability of converters in parallel. Then, a hybrid damping control is proposed to reconstruct the damping characteristics of converters to suppress the parallel resonance spike and reduce the resonance frequency offset. And the parameter selection of the control system is optimized through a stability analysis of the tracking performance and anti-disturbance performance of the HD-ADRC controller. Finally, all the theoretical considerations are verified by simulation and experimental results based on the Matlab/Simulink 2018B and dSpace platform. The simulation and experimental results show that the PI controller gives a THD of 5.33%, which is reduced to 4.66% by employing the HD-LADRC, indicating an improved decoupling between the converters working in parallel with the proposed control scheme.

Drill string vibrational analysis and parametric optimization for a portable water well rig development

The vibration of a drill string is a key topic of study in drilling and mining engineering. Excessive Drill String (DS) vibrations can lead to early failure of bits due to fatigue, Drill Pipe (DP) fractures, bearing damage, and a decrease in the Rate of Penetration (ROP). This occurs when the drill string rotates at its natural frequency, which is known as resonance. A modal and harmonic vibrational analysis of a drill string up to 60-65 meters long was conducted in a vertical water well through parametric studies. This project investigates the vibration of a drill string under various parameters, including drill string lengths, Weight on Bit (WOB), and drill string rotational speeds. The Rotational Speed (RS) in the drill string induces lateral vibrations and stick-slip in torsional vibrations. Finite element modeling of the drill string was performed using ANSYS Workbench (Mechanical). Modal and harmonic frequencies were determined to obtain the optimal drill string length and rotational speeds, using Campbell diagrams and varying weights on bits. Different weights on the bit were assumed to simulate the drilling environment. One of the modern methods used to simulate dynamic behavior in drilling operations is random vibrational analysis. A random vibrational analysis of the drill string was performed in a vertical water well using ANSYS Workbench 2020. This analysis aimed to identify the frequency response of the drill string, with the probability of deformation for each sigma under random vibration being evaluated. The analysis indicated a higher probability approximately 99.7% of failure along the axis of the supplied PSD acceleration. The response power spectral density (RPSD) was analyzed in the x, y, and z directions, focusing on any point in the bottom hole assembly, primarily the bit. The response PSD results indicated that as the Drill Pipe (DP) increased, resonance spikes rose across all axes, leading to lateral and longitudinal vibrations in the drill string. These findings highlight lateral movement as a primary cause of vibration, offering insights for optimizing drilling parameters.

A Hybrid Active Damping Strategy for Improving the Adaptability of LCL Converter in Weak Grid

In a weak grid, the line impedance variation will cause the resonant frequency of the LCL filter to shift towards lower frequencies, thus reducing the quality of the grid-connected current and affecting the power grid stability. To solve this problem, a hybrid active damping strategy with feedforward compensation is proposed for the neutral point clamped (NPC) LCL grid-connected inverter system. In order to reshape the output conductance of the grid-connected system, suppress the resonance spikes of the LCL filter and improve the adaptability of the grid-connected system to the weak grid. A first-order low-pass filter is designed in the grid-connected current loop, and an active damping control of grid-connected current based on a first-order high-pass filter is also proposed. Compared with the conventional capacitive current active damping, no additional sensors are required, and the use of a differential is avoided, which reduces the high-frequency noise. The use of passive resistors is reduced, which reduces the power loss of the grid-connected system. In addition, a point of common coupling (PCC) voltage feedforward strategy based on a low-pass filter is designed to suppress the background higher harmonics at PCC and improve the quality of grid-connected current. In this work, the robustness of the system is analyzed when the parameters of the LCL filter change. Finally, the virtual space vector modulation strategy is used to balance the neutral voltage of the DC bus. Simulation and experimental results show that the control strategy can effectively improve the adaptability of the system to the weak power grid, improve the quality of grid-connected current, and demonstrate strong stability. The THD can be decreased by 0.2% at least, and the improvements are more significant with larger line impedance; the THD is only 2.33% even at 10 mH line impedance.

Designing Parameters to Reshape the Inverter Output Impedance Based on the D-Split Method under Weak Grid Conditions

Novel energy generation technologies, such as high-permeability wind power and photovoltaic systems, exhibit inherent intermittency, randomness, and volatility. During periods of energy production from these sources, the impedance of the electrical grid frequently experiences significant fluctuations. Consequently, the grid manifests characteristics akin to a weak grid, highlighting the challenges associated with integrating renewable energy sources with variable output profiles. These fluctuations lead to a shift in resonance spikes of the LCL-type filter towards the lower frequency band, consequently impacting the stability of inverter grid connections. To mitigate this issue, the present study introduces a novel approach integrating the D-split method and a proportional–differential feedforward strategy. This combination aims to reshape the inverter’s output impedance, ensuring its consistent stability even amidst significant fluctuations in grid impedance. In this research, the optimal controller parameters for systems operating under robust grid conditions are initially determined. This selection process involves the application of the D-split method, supported by graphical visualization. Additionally, the amplitude and phase angle margin tester is employed while considering the system bandwidth as a limiting constraint. Moreover, accounting for the influence of grid impedance, the D-split method is reapplied to ascertain the most suitable values for the proportional–differential feedforward parameters. This adjustment aims to enhance the adaptability of the grid-connected inverter specifically in scenarios characterized by a weak grid. The hardware-in-the-loop (HIL) simulation results demonstrate that despite the presence of harmonics within the grid and a short circuit impedance ratio (SCR) of 3, the inverter maintains grid stability and effectively suppresses harmonics. Moreover, the total harmonic distortion factor (THD) of the grid-connected current remains below 5%.

Notch-band eliminator wideband CSRR loaded monopole fractal antenna for ISM and PCS communications

PurposeThis paper aims to present a low-cost, edge-fed, windmill-shaped, notch-band eliminator, circular monopole antenna which is practically loaded with a complementary split ring resonator (CSRR) in the middle of the radiating conductor and also uses a partial ground to obtain wide-band performance.Design/methodology/approachTo compensate for the reduced value of gain and reflection coefficient because of the full (complete) ground plane at the bottom of the substrate, the antenna is further loaded with a partial ground and a CSRR. The reduction in the length of ground near the feed line improves the impedance bandwidth, and introduced CSRR results in improved gain with an additional resonance spike. This results in a peak gain 3.895dBi at the designed frequency 2.45 GHz. The extending of three arms in the circular patch not only led to an increase of peak gain by 4.044dBi but also eliminated the notch band and improved the fractional bandwidth 1.65–2.92 GHz.FindingsThe work reports a –10dB bandwidth from 1.63 GHz to 2.91 GHz, which covers traditional coverage applications and new specific uses applications such as narrow LTE bands for future internet of things (NB-IoT) machine-to-machine communications 1.8/1.9/2.1/2.3/2.5/2.6 GHz, industry, automation and business-critical cases (2.1/2.3/2.6 GHz), industrial, society and medical applications such as Wi-MAX (3.5 GHz), Wi-Fi3 (2.45 GHz), GSM (1.9 GHz), public safety band, Bluetooth (2.40–2.485 GHz), Zigbee (2.40–2.48Ghz), industrial scientific medical (ISM) band (2.4–2.5 GHz), WCDMA (1.9, 2.1 GHz), 3 G (2.1 GHz), 4 G LTE (2.1–2.5 GHz) and other personal communication services applications. The estimated RLC electrical equivalent circuit is also presented at the end.Practical implicationsBecause of full coverage of Bluetooth, Zigbee, WiFi3 and ISM band, the proposed fabricated antenna is suitable for low power, low data rate and wireless/wired short-range IoT-enabled medical applications.Originality/valueThe antenna is fabricated on a piece (66.4 mm × 66.4 mm × 1.6 mm) of low-cost low profile FR-4 epoxy substrate (0.54 λg × 0.54 λg) with a dielectric constant of 4.4, a loss tangent of 0.02 and a thickness of 1.6 mm. The antenna reflection coefficient, impedance and VSWR are tested on the Keysight technology (N9917A) vector network analyzer, and the radiation pattern is measured in an anechoic chamber.

A Damping Control Strategy to Improve the Stability of Multi-Parallel Grid-Connected PCSs

In this study, to ensure stable operation of multi-parallel PCSs, a damping control strategy is adopted to restrain resonance characteristics of a parallel system, and the stability of the system is analyzed. First, the mathematical model of a single PCS is built, the capacitive current feedback-type active damping control strategy is introduced, and the effect of the damping control strategy on a single PCS under proportional-integral (PI) control is analyzed. Then, under the presence of grid impedance, a single PCS model is established and extended to multi-parallel PCSs, where a single PCS is replaced by a Norton’s equivalent circuit. The active damping method is developed, and Bode diagrams are utilized to verify that it can effectively suppress the resonance spikes of a parallel system. Finally, a simulation model of four PCSs in parallel operation is built on the Simulink platform, and the results support the correctness of the theoretical analysis.

An active filtering strategy of LCL filter for inverter power supply of electromagnetic pump

The inverter power supply for an electromagnetic pump is a motor controller based on a three-phase inverter. This inverter needs to be followed by an LCL filter as a filter for connecting the electromagnetic pump. But the LCL filter has a large resonance spike at the resonance point. This can cause relatively large interference to the control system and also increase the harmonics of the inverter power supply output current. Therefore, it is necessary to suppress the resonant spikes of the LCL filter. In this paper, an active filtering strategy based on a trap is proposed by comparing the existing passive filtering strategies. The trap can be used to generate an anti-resonant peak at the resonance point of the LCL, which is used to cancel the resonant spike of the LCL filter. This method ensures the resonant peak suppression effect without affecting the filtering effect of the LCL filter.

A Hybrid EMC Testing Facility: Combining Transmission Line and Reverberation Chamber Measurement System

By combining a transmission line system (TLS) and a reverberation chamber (RC), a hybrid electromagnetic compatibility (EMC) testing facility is designed and constructed. Generally, the lowest usable frequency (LUF) of an RC is limited by its dimension, which limits the application of RCs for EMC testing at low frequencies. Therefore, to improve the field uniformity (FU) of an RC at frequencies lower than the LUF, a TLS is integrated into the RC. After optimizing the load resistance, length, and width of the TLS, the resonant frequency and electric field spikes of the hybrid system are eliminated. The FU of the E-field in the system is greatly improved in the frequency range of 0-30 MHz. Moreover, using an oscillating wall stirrer in the RC, the FU satisfies the standard (IEC 61000-4-21) above 80 MHz. Results show that combining the TLS and the RC testing system could be widely used for EMC testing in the frequency range of 0-30 MHz and 80 MHz-6 GHz.

Understanding oscillons: Standing waves in a ball

Oscillons are localized long-lived pulsating states in the three-dimensional ${\ensuremath{\phi}}^{4}$ theory. We gain insight into the spatiotemporal structure and bifurcation of the oscillons by studying time-periodic solutions in a ball of a finite radius. A sequence of weakly localized Bessel waves---nonlinear standing waves with the Bessel-like $r$-dependence---is shown to extend from eigenfunctions of the linearized operator. The lowest-frequency Bessel wave serves as a starting point of a branch of periodic solutions with exponentially localized cores and small-amplitude tails decaying slowly toward the surface of the ball. A numerical continuation of this branch gives rise to the energy-frequency diagram featuring a series of resonant spikes. We show that the standing waves associated with the resonances are born in the period-multiplication bifurcations of the Bessel waves with higher frequencies. The energy-frequency diagram for a sufficiently large ball displays sizeable intervals of stability against spherically symmetric perturbations.

An active damping control strategy with improved transient performance for high‐frequency AC power distribution in intelligent vehicles

SummaryHigh‐frequency AC (HFAC) LCLC resonant inverter has recently received more and more attention in power distribution system (PDS) of intelligent vehicles. However, LCLC resonance complicates the design of a current control loop and can even threaten the stability and transient performance of PDS. Active damping (AD) strategies based on the feedback of a single filter voltage or current have been shown to be effective and cost‐efficient method for attenuating resonant spikes. In this paper, a notch filter‐based AD (NFAD) control strategy is proposed to improve the stability and transient performance of PDS for intelligent vehicles. By sensing and feeding back the output resonance current of LCLC resonant inverter, the NFAD control strategy is then formulated to emulate a virtual impedance in order to improve the system phase margin and crossover frequency. Hence, the proposed control strategy can not only suppress the LCLC double resonance peaks but also effectively improve the transient performance of resonant inverter while guaranteeing the stability of the system. Finally, an experimental prototype was established and tested to verify the effectiveness of the proposed control strategy with a rated output power of 130 W, an operation frequency of 25 kHz, and a sinusoidal output voltage of 28 V (rms).

Modeling and stability analysis of interaction between converters in AC-DC distribution systems

With the development and promotion of AC-DC distribution systems, the stability of multi-terminal systems has drawn much interest. This paper analyzes the instability phenomena in AC-DC distribution systems by considering the interactions between converters. The typical structure and control strategy of double-terminal AC-DC distribution systems under master-slave control is introduced. Then an AC-DC distribution system model is developed taking into account the interaction of the converter control system. The resonant spikes generated by the interaction between the converters are used as the reference object of the interaction to analyze the influence of the converter control parameters and the system electrical parameters on the system stability and interaction. Finally, a double-terminal AC/DC distribution system model is built using PLECS and RTBOX for simulation and semi-physical experimental verification.

A Modified Interleaved Capacitor Clamped DC–DC Converter With Non-Resonant Soft Switching

Since the solar panels and fuel cells have low output voltage, which need to be converted to the 400 V or higher dc bus voltage in the renewable energy power generation systems, where, the high gain dc–dc converter plays a key role. Furthermore, with the requirement of the converter in low cost and high efficiency, the soft-switching interleaved boost-type converters based on switched-capacitor and voltage multiplier cell as the high gain dc–dc converters have been widely applied. However, the above-mentioned soft-switching interleaved boost-type converters in literature have resonant spikes on the switches or there are coupled inductors, which will cause the high cost due to the large stresses of the switches or low efficiency due to the high core losses of the coupled inductors. To solve the above-mentioned problems, a modified interleaved capacitor clamped (MICC) dc–dc converter with non-resonant soft-switching (NRSS) is proposed, in which only an auxiliary inductor operating in discontinuous conduction mode with few μH is used to achieve the zero-current-switching for all switches and diodes. Furthermore, the operating principle of the proposed converter is given, the interleaved boost structure is used as the front stage of the proposed converter to reduce the input current ripple and lighten the current stress on all switches and magnetic components, the MICC structure with NRSS as the output stage is proposed as a voltage multiplier module to achieve the high voltage gain. Then, the circuit parameter design for this converter is presented. Finally, a 400 W experimental prototype is built to verify the correctness and the effectiveness of the proposed topology.

An Improved Electric Spring Topology Based on LCL Filter

Electric spring (ES), which has been widely discussed in recent years, is a new demand response method. By adjusting the power of noncritical load (NCL), ES can adaptively improve power quality of the grid containing a high proportion of renewable energy sources. Most of the existing ESs is connected in series with NCLs, but this structure limits the compensation power range of ES. In this article, a new ES topology based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> filter is proposed, where NCL is paralleled with the capacitor branch as the shunt damper. Compared with other types of ES, the proposed <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -ES has the advantages which can extend the adjustable power range, improve the voltage regulation performance, and suppress the inherent resonance spikes effectively. Finally, the feasibility of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCL</i> -ES has been verified by simulation and experimental results.

Modelling, analysis, and parameters design of filter‐integrated three‐switch boost inverter

By combining the filter circuit and boost circuit, the filter-integrated three-switch boost inverter (TSBI) is proposed in this paper. Different from the traditional boost inverter, TSBI achieves the boost function at the AC side, so the voltage stress on the switches is small. Through modelling and analysis, the boosting characteristics and filtering characteristics of the system are obtained. The proposed topology can significantly suppress the resonance spike and does not need to add additional filtering equipment, which can reduce the volume of equipment and system loss. In order to clearly illustrate the advantages and disadvantages of the proposed topology, this paper makes a detailed comparison with other types of inverters. Finally, the feasibility of the system is verified by experiment and simulation.

A resonant damping control and analysis for LCL-type grid-connected inverter

The inverter becomes an essential part in the distributed energy units, where an inductor–capacitor–inductor (LCL) filter is an up-to-date adoption for grid interfacing. However, the challenging issue of resonance related to the LCL-filter worsens the dynamic control characteristics and produces stability threat for the voltage source inverter system. The proper design of inverter control plays a substantial part in ensuring a steady state operation and a high quality of grid injected current according to grid connection codes. This paper offers a different design method of inverter control which alters the inner damping loop structure to enhance the damping and stability features of the inverter system. In the proposed solution, a modified compensator is employed through the LCL filter network and filter capacitor current feedback loop, the resultant augmented plant’s output is then sent back at the reference point of a grid-connected inverter system to damp the unwanted resonance spike. This particular arrangement to form a damping loop is termed as parallel feedforward compensation. The damping loop is implemented by calculating the filter capacitor current, and a first order high-pass filter is employed as a damper in the suggested arrangement. Moreover, for comparative studies and analysis, the conventional filter capacitor current feedback active damping method is selected. In addition, the stability margins and control performance of the open current loop are examined under different filter parameters values. The substantial results of the suggested structure are quicker dynamic response, comparatively improved resonance damping, better tracking performance and higher delay compensation capability. A laboratory prototype is established to confirm the effectiveness of the suggested scheme on the bases of control performance and stability margins.

Parameter optimization design and performance analysis of filter‐integrated switched boost grid‐connected inverter

AbstractThis paper proposes a filter‐integrated switched boost grid‐connected inverter by coupling switched boost network between inverter bridge and power grid, which can effectively solve the inherent resonance peak problem of LCL filter. Meanwhile, the proposed topology can realize boost function at AC side, which can effectively avoid the problem of excessive voltage stress caused by the boost at the DC side. Due to the design of the parameters in the control system will affect the effect of resonance spike damping, it will also affect the harmonic content of the grid‐connected current. Based on the stability margin and steady‐state error of the system, combined with the characteristics of the system regulator, the parameter selection area that meets the system requirements is drawn in this paper, and the optimization of the system parameter design method is realized. Finally, the function of the circuit is verified by building an experimental platform.

Design and Measurement of a Broadband Beryllium Oxide Window With High Power Handling Capability

A broadband dielectric window with high power handling capability for gyrotron traveling wave tubes (gyro-TWTs) had been designed based on the step-type impedance transition structure. The manufactured beryllium oxide (BeO) window can achieve a relative bandwidth of 35.3% with a maximum reflection of −20 dB in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> -band, and the corresponding transmission loss is over −0.1 dB. The resonant spikes caused by engineering factors, including assembly tilt and gap, are investigated and analyzed. Thermal analysis shows that the BeO window can achieve a high average/CW power handling capability of over 232 kW within a wide frequency range. The fabricated input window has been successfully applied in our <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> -band broadband and high-power gyro-TWT.

A New Method of LCL Filter Parameter Design Based on Fish Swarm Algorithm

Aiming at the problem that LCL filter is better than L, LC filter in filtering performance. However, the selection of parameters is more complicated, and it is prone to resonant spikes in the filtering process, this study introduces passive damping to measure its resonant spikes suppression, and combined with the attenuation of the grid-connected harmonic current of the LCL filter to measure its excellent filtering performance. Based on this, the objective function model is established, the fish swarm algorithm is adopted to optimize its parameters, and the grid-connected simulation model is found in MATLAB/Simulink. Its filtering effect is compared with the traditional method. The simulation proves that the filter after parameter optimization can effectively suppress and filter the harmonic components of the inverter output voltage compared with the conventional filtering method, and provide positive theoretical guidance for the stable grid connection of new energy power generation.

Topology and Control Strategy of PV MVDC Grid-Connected Converter with LVRT Capability

This paper proposes an isolated buck-boost topology and control strategy for the photovoltaic (PV) medium-voltage DC (MVDC) converter with low-voltage ride through (LVRT) capability. The proposed isolated buck-boost topology operates on either boost or buck mode by only controlling the active semiconductors on the low-voltage side. Based on this topology, medium-voltage (MV) dc–dc module is able to be developed to reduce the number of modules and increase the power density in the converter, which corresponds to the first contribution. As another contribution, a LVRT method based on an LC filter for MVDC converter is proposed without additional circuit and a feedback capacitor current control method for the isolated buck-boost converter is proposed to solve the instability problem caused by the resonance spike of the LC filter. Five kV/50 kW SiC-based dc–dc modules and ±10 kV/200 kW PV MVDC converters were developed. Experiments of the converter for MVDC system in the normal and LVRT conditions are presented. The experimental results verify the effectiveness of the proposed topology and control strategy.

Active Damping and Passive Control Strategy for Three-Phase LCL Grid-Connected Inverter

Compared with traditional controllers such as PI based on classic control theory, the article applies passive control (PBC) theory to the design of three-phase LCL grid-connected inverter controllers. The mathematical model of the system based on Euler-Lagrange (EL) is established, and the damping method of the trap is used to suppress the resonance spikes generated by the system, so that the system meets the requirements of grid connection. The simulation results verify the feasibility of the scheme.