Power Coupling Research Articles

A phenomenological model of the fundamental power coupler for a superconducting resonator

A phenomenological model of the fundamental power coupler for a superconducting resonator

Power exchanged between subsystems with non-diffuse fields in statistical energy analysis.

This article is a discussion on the necessity of the assumption of diffuse field in statistical energy analysis and the validity of the coupling power proportionality which states that the vibrational power exchanged between coupled subsystems is proportional to the difference of their modal energies. It is proposed to re-formulate the coupling power proportionality in terms of local energy density instead of modal energy. We show that this generalized form remains valid even if the vibrational field is not diffuse. Three causes of lack of diffuseness have been studied: coherence of rays in symmetrical geometries, nonergodic geometries, and the effect of high damping. Numerical simulations and experimental results conducted on flat plates in flexural vibration are provided to support these statements.

An Efficient and Stable Embedded Multi-U-Shaped Column Rotary Transformer

Inductively Coupled Power Transfer (ICPT) technology can be used to solve the problems of high friction loss, overheating and low stability caused by conductive slip rings on rotating power supply equipment. An improved Embedded Multi-U-Shaped Column Rotary Transformer (EMUCRT) based on the ICPT and spliced core structure is proposed in this paper. It has a higher coupling coefficient and can transmit power more efficiently and stably due to the primary magnetic core is embedded inside the secondary magnetic core. Compared with the one-piece core structure, the spliced type is more flexible due to its loose magnetic core arrangement. Its primary coil can still transmit energy stably after offset by a certain distance, so the structure has good anti-misalignment ability. On the basis of analyzing its magnetic core arrangement and magnetic circuit model, the optimal magnetic core specifications and quantities of primary and secondary side are obtained by theoretical calculation and simulation. In order to verify the high efficiency, rotational stability and anti-misalignment characteristics of the structure, an experimental prototype was built. The results show that EMUCRT can transmit energy efficiently and has good rotational and offset stability.

RF power coupling of RAON RFQ

A radio frequency quadrupole (RFQ) has been constructed as a front accelerator for a rare isotope accelerator facility. The RFQ has two power couplers that are operated simultaneously for high power operation to accelerate from proton to uranium. Coaxial transmission lines have been adopted to connect each power coupler to the 80 kW solid state power amplifier(SSPA) which is consisted with combiners, circulators and 5 kW unit amplifiers. In this study, the coupling to the cavity with two power couplers was investigated for the failure of RF power units. Moreover, the operation scenario of the RFQ linac was also presented in considering the availability.

Thermal stability model of power coupler niobium tube for accelerator based on multi-field coupling analysis

The power coupler is the key component of superconducting accelerator, and its thermal stability will seriously affect the stable operation of the superconducting cavity. The niobium (Nb) tube at the end of the power coupler directly connected to the superconducting cavity is taken as the research object, and a one-dimensional thermal stability model based on multi-field coupling analysis is established. The coupling relationship between the electromagnetic field, liquid helium boiling heat transfer and temperature field is considered. The finite difference method was used to discretize the control equations of the model, and the Newton-Raphson method was used to handle the influence of material parameters and internal heat sources nonlinearity on the accuracy and stability of the discrete equations. The results show that the thermal stability of the Nb tube can be improved by controlling the upstream heat leakage and maintaining the upstream temperature below 9.2 K. Under transient conditions, timely recovery of the upstream cooling capacity can stop the quench caused by the decrease of cooling capacity and restore the superconducting state. The maximum quench propagation speed caused by the increase of magnetic field is 0.188 m/s, which is higher than that caused by the decrease of cooling capacity. When the local region of the liquid helium contact enters the film boiling 0.0034 s, the entire region will enter the film boiling, and the maximum temperature will reach 11.3 K, which will cause the thermal quench of the superconducting cavity. The model can accurately analyze the factors affecting the thermal stability of Nb tube and provide a reliable theoretical basis for the thermal design and stable operation of this type of power coupler.

A joint clearing market for coupled electricity and gas system considering bilateral energy contracts

In recent years, with the progress of new energy conversion technology, especially an increasing number of gas turbine units applied to the market, the connection between the natural gas system and the electric system has become increasingly close. Initially the gas and electricity markets operated relatively independently. Therefore, it is necessary to establish the coupling architecture of natural gas market and electricity market to meet the energy demand of users. This paper attempts to propose a power and gas coupling system based on clearing market structure. Firstly, the difference between natural gas–electricity coupling market and joint settlement market is discussed. The combined market considered in this paper is somewhat different from the associated electricity market and natural gas market. The calculations are easier and the results more reliable than those of the traditional linked gas markets and electric power market. Then, a mathematical model of joint clearing market is established based on bilateral energy contracts. Then, the piecewise linearization approximation (PLA) algorithm is proposed to solve the nonlinear problem. The locational piecewise price (LMEP) and locational marginal gas price (LMGP) are identified respectively, and the bilateral contracts are processed. The solution proposed in this paper guarantees strong duality and clear meaning of dual variables, making PLA easy to apply and solve market clearing problems based on dual variables or Lagrange multiplier pricing, as well as easy to deal with bilateral contract problems. Finally, the proposed joint clearing market is verified by an improved 3-electric bus and 6-gas node system.

Impacts of hybridization and forecast errors on the probabilistic capacity credit of batteries

Battery storage is increasingly identified as being among the least-cost mix of technologies in the evolving U.S. electricity mix. This study explores the marginal capacity credit of batteries using a probabilistic, reliability-based, effective firm capacity method, which we apply for multiple battery power ratings, durations, coupling types, deployment locations, and dispatch profiles within a test system that is based on the Texas Interconnection in the year 2024. We find that the capacity credits for all battery durations depend on their ability to predict the timing of reliability events. Even 1–2 h forecast errors—resulting in early or delayed battery discharging relative to the onset of a reliability event—lead pronounced capacity credit reductions, especially for 4-h duration batteries. Coupling batteries with solar mitigates the uncertainty associated with a shorter-duration battery’s availability during reliability events, primarily due to the relatively high solar capacity credit in our test system. Coupled (or hybrid) system designs with oversized solar arrays, the ability to charge the coupled battery with grid energy, and larger batteries lead to the greatest capacity credit benefits of hybridization. We do not see evidence that the hybrid capacity credit exceeds the sum of the separate battery and solar capacity credits.

The development of wireless charging technology in the electric vehicle

Greenhouse gas emissions have caused the global climate to deteriorate, and the consumption of oil resources is becoming less cost-effective. Electric vehicles (EVs) are a good way to reduce this negative impact. However, the energy density of batteries is too low compared with oil, so electric cars need to be recharged repeatedly. This paper provides a comprehensive review of all the wireless charging technologies for EVs. The technology principle of Inductively Coupled Power Transfer (ICPT), Magnetically Coupled Resonant Wireless Power Transfer (MCR-WPT) and Microwave Power Transfer (MPT) are discussed by a comparative analysis between the three technologies. The analysis found that MCR-WPT is the best technology because it has high efficiency and very little radiation. After that, wireless charging is expounded from both static and dynamic perspectives. Next, different national requirements and standards for wireless charging are presented. According to the economic and safety analysis, it is found that wireless charging technology can avoid many security risks, reduce the occupied area and has a longer service life than wired charging.

Low beta superconducting cavity system design for HIAF iLinac

A superconducting ion-Linac (iLinac), which is supposed to work as the injector in the High Intensity heavy-ion Accelerator Facility project, is under development at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. The iLinac is a superconducting heavy ion linear accelerator approximately 100 meters long and contains 96 superconducting cavities in two types of 17 cyromodules. Two types of superconducting resonators (quarter-wave resonators with a frequency of 81.25 MHz and an optimal beta β = v/c = 0.07 called QWR007 and half-wave resonators with a frequency of 162.5 MHz and an optimal beta β = 0.15 called HWR015) have been investigated. The cavity design included extensive multi-parameter electromagnetic simulations and mechanical analysis，and its results are described in details. The fundamental power coupler and cavity dynamic tuner designs are also presented in this article. The prototypes are under manufacturing and expected to be ready in 2023.

Optimal Sizing and Operation of Hybrid Renewable Power Plants Participating in Coupled Power Markets with Different Execution Times

The increasing limitations in the use of fossil fuels due to their limited availability and pollution have increased the use of renewable energies and storage systems for electricity generation. To achieve the goals of the integration of renewable energy, sizing and management methods for hybrid plants are needed to make investments profitable and attractive in these resources. This work presents an optimization method for the sizing and operation of hybrid plants with storage, choosing the best combination of technologies based on resource availability, installation costs and market prices, maximizing an economic index such as the net present value. One of the main contributions of this work is to reduce the oversizing that occurs in traditional methods through a penalty term for lost energy, encouraging investment in batteries to store excess energy above the point of interconnection (POI). In addition, it is intended to cover gaps such as the operation in coupled markets with different execution periods to maximize the benefits of the investment made and to contemplate different generation alternatives together with storage. The presented method is tested through sizing and operation simulations to demonstrate its potential. The presented method is tested through sizing and operation simulations to demonstrate its potential. In scenario A, the best combination of solar energy, photovoltaic energy and storage, is chosen. In scenario B, it is shown how the curtailment of the oversizing is reduced in some months by more than 5%. In scenario C, for daily operation in coupled markets, it is possible to improve the benefits from 0.7% to 37.04% in the days of the year.

Modified virtual frequency‐voltage frame control scheme with zero sharing error for islanded AC microgrids

AbstractThe active power‐virtual frequency (P‐ω′) and reactive power‐virtual voltage (Q‐V′) droop control scheme has been suggested for coordinated control of distributed energy resources (DERs) in islanded microgrids. While this method mitigates the issue of active and reactive power coupling in the droop controller, its main limitation is power‐sharing error. Due to the local property of the virtual frequency and voltage, significant steady‐state errors occur for both active and reactive power sharing. In this paper, a decentralized method is proposed to eliminate the mentioned errors without utilization of communication links. In the proposed scheme, P‐ω′ and Q‐V′ droops are realized at the microgrid point of common coupling (PCC). By employing the PCC virtual frequency/voltage for the active/reactive power sharing of all DERs, the sharing errors caused by the local property are eliminated. Small signal stability of the proposed scheme is studied, and Hardware‐in‐the‐Loop (HIL) experimental results are presented to validate the proposed method and highlight the improvements compared with the conventional P‐ω′/Q‐V′ scheme. The results verify the efficacy of the proposed method for providing accurate active and reactive power sharing while regulating the frequency and voltage close to the rated values.

Automatic turbulence mitigation for coherent free-space optical links using crystal-based phase conjugation and fiber-coupled data modulation.

There are various performance advantages when using temporal phase-based data encoding and coherent detection with a local oscillator (LO) in free-space optical (FSO) links. However, atmospheric turbulence can cause power coupling from the Gaussian mode of the data beam to higher-order modes, resulting in significantly degraded mixing efficiency between the data beam and a Gaussian LO. Photorefractive crystal-based self-pumped phase conjugation has been previously demonstrated to "automatically" mitigate turbulence with limited-rate free-space-coupled data modulation (e.g., <1 Mbit/s). Here, we demonstrate automatic turbulence mitigation in a 2-Gbit/s quadrature-phase-shift-keying (QPSK) coherent FSO link using degenerate four-wave-mixing (DFWM)-based phase conjugation and fiber-coupled data modulation. Specifically, we counter-propagate a Gaussian probe from the receiver (Rx) to the transmitter (Tx) through turbulence. At the Tx, we generate a Gaussian beam carrying QPSK data by a fiber-coupled phase modulator. Subsequently, we create a phase conjugate data beam through a photorefractive crystal-based DFWM involving the Gaussian data beam, the turbulence-distorted probe, and a spatially filtered Gaussian copy of the probe beam. Finally, the phase conjugate beam is transmitted back to the Rx for turbulence mitigation. Compared to a coherent FSO link without mitigation, our approach shows up to ∼14-dB higher LO-data mixing efficiency and achieves error vector magnitude (EVM) performance of <16% under various turbulence realizations.

Tight power and energy coupling constraints of energy storage resources for unit commitment

AbstractEnergy Storage Resources (ESRs) can help promote high penetrations of renewable generation and shift the peak load. However, the increasing number of ESRs and their features different from conventional generators bring computational challenges to operations of wholesale electricity markets. In order to improve the computational efficiency, this paper tightens the generic ESR formulation for unit commitment. To avoid the complexity caused by ESR operations in both discharge and charge directions, a novel “decoupled analysis” is conducted to analyze one direction at a time. For each direction, ESRs over two and three time periods are categorized into several types based on their parameters. For each type, our recent four‐step systematic formulation tightening approach is used to construct the corresponding tight formulation. In order to consider more periods without analyzing all the drastically increased number of types, a series of major types are selected based on how many periods an ESR is able to discharge (charge) consecutively at the upper power limit. A related generic form of tight constraints over multiple periods is established. Moreover, validity and facet‐defining proofs of our tight constraints have been provided. Numerical testing results illustrate the tightening process and demonstrate computational benefits of the tightened formulations.

Experimental characterization of a planar phase-engineered metamaterial lenslet for millimeter astronomy.

To unveil presently inscrutable details of the origins of our universe imprinted in the cosmic microwave background, future experiments in the millimeter and submillimeter range are focusing on the detection of fine features, which necessitate large and sensitive detector arrays to enable multichroic mapping of the sky. Currently, various approaches for coupling light to such detectors are under investigation, namely, coherently summed hierarchical arrays, platelet horns, and antenna-coupled planar lenslets. The last option offers increased bandwidth and a simpler fabrication while maintaining the desired optical performance. In this work, the design, fabrication, and experimental characterization of a prototype planar metamaterial phase-engineered lenslet operating in W-band [75GHz; 110GHz] is presented. Its radiated field, initially modeled and measured on a systematics-limited optical bench, is compared against a simulated hyperhemispherical lenslet, a more established technology. It is reported here that our device reaches the cosmic microwave background (CMB) specification for the next stages of experiments, demonstrating power coupling above 95% and beam Gaussicity above 97% while maintaining ellipticity below 10% and a cross-polarization level below -21d B through its operating bandwidth. Such results underline the potential advantages our lenslet can offer as focal optics for future CMB experiments.

Fully Distributed Dynamic Edge-Event-Triggered Current Sharing Control Strategy for Multibus DC Microgrids With Power Coupling

Although the current sharing control of dc microgrids has been widely studied, the high communication bandwidth and global communication network structure information demands hander the renewable energy consumption. Thus, this article proposes a fully distributed dynamic edge-event-triggered current sharing control strategy for multibus dc microgrids with power coupling. First, the system model with power coupling is built, which is further switched to the linear heterogeneous multiagent systems with unknown disturbance. It is an indispensable preprocessing for controller design. Furthermore, the fully distributed current sharing control strategy is proposed through adaptive coupling weights. Note that the global communication network structure information demand is eliminated. Moreover, the fully distributed dynamic edge-event-triggered mechanism is proposed to reduce communication bandwidth. Compared with the previous dynamic event-triggered mechanisms applied into dc microgrids, the continuous communication between neighboring agents is avoided, and controller updating frequency is reduced. Finally, the simulation and experimental results verify the proposed control performance.

Characteristics of segmented dielectric window inductively coupled plasma

In this study, a novel inductively coupled plasma (ICP) system is proposed. It comprises a segmented dielectric window and a metal frame. For the proposed ICP system, a thin window can be designed, thereby compensating for the power loss caused by the metal frame. The proposed ICP system has two potential advantages: it can enhance the controllability of the gas flow field and it can reduce the capacitive power coupling. These characteristics enable the superior uniformity and reliable operation of ICP systems for semiconductor processes. The characteristics of the proposed ICP system are investigated using three-dimensional fluid self-consistent plasma simulations and experiments. The proposed ICP system exhibits performance similar to that of the conventional ICP system currently used in etching and deposition processes.

Planar Array of UWB Active Slot Antennas for Microwave Imaging of the Breast

A shielded planar array of active slot antennas is proposed for applications in the microwave imaging of the breast. The frequency band is from 3 to 8 GHz, where reflection loss better than 10 dB and interelement mutual coupling less than −20 dB are achieved. The center-to-center element spacing is 12 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times12$ </tex-math></inline-formula> mm. A low-noise amplifier (LNA) is integrated with each antenna element for use in a receiving configuration. A ground plane within the multilayer design separates the antenna array from the electronics array while providing shielding from the back and improving the power coupling into the tissue. The proposed structure resolves an outstanding problem in the design of large shielded antenna arrays for tissue imaging, namely, the interconnects between the array elements and the electronic circuits, which are separated by multiple dielectric layers and a grounded plane. The critical development is the new low-reflection triple-wire vertical transition that carries the signal from the antenna layer to the electronics layer while traversing through multiple layers of different permittivities and through openings in the ground plane. The design is verified by simulations and measurements. The passive and active designs are compared, illustrating the full utilization of the LNA gain. The performance of the proposed active array is also examined in imaging experiments with a compressed-breast phantom.

Neural substrates of cognitive impairment in a NMDAR hypofunction mouse model of schizophrenia and partial rescue by risperidone.

N-methyl D-aspartate receptor (NMDAR) hypofunction is a pathophysiological mechanism relevant for schizophrenia. Acute administration of the NMDAR antagonist phencyclidine (PCP) induces psychosis in patients and animals while subchronic PCP (sPCP) produces cognitive dysfunction for weeks. We investigated the neural correlates of memory and auditory impairments in mice treated with sPCP and the rescuing abilities of the atypical antipsychotic drug risperidone administered daily for two weeks. We recorded neural activities in the medial prefrontal cortex (mPFC) and the dorsal hippocampus (dHPC) during memory acquisition, short-term, and long-term memory in the novel object recognition test and during auditory processing and mismatch negativity (MMN) and examined the effects of sPCP and sPCP followed by risperidone. We found that the information about the familiar object and its short-term storage were associated with mPFC→dHPC high gamma connectivity (phase slope index) whereas long-term memory retrieval depended on dHPC→mPFC theta connectivity. sPCP impaired short-term and long-term memories, which were associated with increased theta power in the mPFC, decreased gamma power and theta-gamma coupling in the dHPC, and disrupted mPFC-dHPC connectivity. Risperidone rescued the memory deficits and partly restored hippocampal desynchronization but did not ameliorate mPFC and circuit connectivity alterations. sPCP also impaired auditory processing and its neural correlates (evoked potentials and MMN) in the mPFC, which were also partly rescued by risperidone. Our study suggests that the mPFC and the dHPC disconnect during NMDAR hypofunction, possibly underlying cognitive impairment in schizophrenia, and that risperidone targets this circuit to ameliorate cognitive abilities in patients.

Hybrid Energy Storage Systems Based on Redox-Flow Batteries: Recent Developments, Challenges, and Future Perspectives

Recently, the appeal of Hybrid Energy Storage Systems (HESSs) has been growing in multiple application fields, such as charging stations, grid services, and microgrids. HESSs consist of an integration of two or more single Energy Storage Systems (ESSs) to combine the benefits of each ESS and improve the overall system performance, e.g., efficiency and lifespan. Most recent studies on HESS mainly focus on power management and coupling between the different ESSs without a particular interest in a specific type of ESS. Over the last decades, Redox-Flow Batteries (RFBs) have received significant attention due to their attractive features, especially for stationary storage applications, and hybridization can improve certain characteristics with respect to short-term duration and peak power availability. Presented in this paper is a comprehensive overview of the main concepts of HESSs based on RFBs. Starting with a brief description and a specification of the Key Performance Indicators (KPIs) of common electrochemical storage technologies suitable for hybridization with RFBs, HESS are classified based on battery-oriented and application-oriented KPIs. Furthermore, an optimal coupling architecture of HESS comprising the combination of an RFB and a Supercapacitor (SC) is proposed and evaluated via numerical simulation. Finally, an in-depth study of Energy Management Systems (EMS) is conducted. The general structure of an EMS as well as possible application scenarios are provided to identify commonly used control and optimization parameters. Therefore, the differentiation in system-oriented and application-oriented parameters is applied to literature data. Afterwards, state-of-the-art EMS optimization techniques are discussed. As an optimal EMS is characterized by the prediction of the system’s future behavior and the use of the suitable control technique, a detailed analysis of the previous implemented EMS prediction algorithms and control techniques is carried out. The study summarizes the key aspects and challenges of the electrical hybridization of RFBs and thus gives future perspectives on newly needed optimization and control algorithms for management systems.

A novel and efficient dual-antenna micro plasma thruster

A novel dual-antenna micro plasma thruster (DMPT) driven by radio-frequency (rf) power supply is proposed and characterized experimentally. The Langmuir probe (LP) and the retarding potential analyzer (RPA) are applied to measure the plasma parameters. The results show that compared to the single-antenna, the dual-antenna yields higher electron density, electron temperature, and ion energy. The measurements from the rf I–V probe indicate that the power coupling efficiency for the dual-antenna is about 2.6 times higher than that for the single-antenna. The plasma potential drop in the plume of the DMPT is the reason for the formation of ion beam. The neutral gas temperature is measured by rovibrational ban matching of the first negative band system of ionic nitrogen (N2+) for operating powers of 20 W up to 100 W. The total thrust of the DMPT has been calculated by the sum of the ion thrust and the neutral gas thrust. The total thrust at 100 sccm argon flow rate and 100 W rf power is ∼2.23 mN, which indicates an up to 168% thrust gain compared to the cold gas thrust, and a significant 11% total thrust is attributed to the ions’ electrostatic acceleration. The specific impulse and thruster efficiency at the above experimental conditions are ∼76 s and ∼0.8%, respectively. These initial results show that the dual-antenna scheme has better performance and is more promising than the traditional single-antenna design for electrodeless micro-electric propulsion. This novel and efficient micro plasma thruster is particularly useful for cubic satellites and scientific experiments in space (such as gravitational wave detection) which require gesture and orbit control of great precision.