arXiv subjects

Xiongfei Wang

Publications and source records attributed to Xiongfei Wang.

At least 19 recordsLinked to original sources

arXiv2026

Global Survey of Technologies and Industrial Applications of Grid Forming Energy Storage Systems

Grid-forming (GFM) energy storage system (ESS) is a key enabler for stabilizing future power systems with high penetration of converter-based resources (CBRs). To get a better overview of the state-of-the-art and challenges for implementing and deploying GFM-ESS, a global survey has been initiated by Cigre Working Group B4.101 - industrial implementation and application of grid forming energy storage systems. Feedback was collected from universities, transmission system operators (TSOs), power plant developers, original equipment manufacturers (OEMs), research institutes, as well as consultants. It is interesting to note that while many common understandings have been established in practice, certain gaps persist among different stakeholders. This article intends to bridge this gap by presenting a summary of the survey, including the questionnaire, responses from various stakeholders, and in-depth analysis of the survey results. The key challenges faced by different stakeholders in deploying GFM-ESS are identified, shedding light on future research in this direction.

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arXiv2026

Geometric Decentralized Stability Certificate of Power Electronics-Dominated Power Systems Covering Variable Operating Points

The integration of power converters is profoundly changing the power system dynamics and poses significant challenges for stability analysis. The dynamic interactions between the power grid and the heterogeneous converters are highly complex and difficult to analyze due to the curse of dimensionality. Moreover, system stability varies with the operating points, which are determined by the voltage magnitude, active power, and reactive power of each converter. This further complicates the analysis as it is difficult to enumerate and examine all the possible operating points. To tackle these challenges, this paper proposes a geometric decentralized stability certificate for power electronics (PE)-dominated power systems, which can simultaneously handle heterogeneous power converters and their variable operating points. The certificate can be checked in a decentralized and modular manner, and it is scalable for large-scale power systems. Our approach is developed based on the concept of Davis-Wielandt (DW) shell and its projections, which can effectively visualize the characteristics of high-dimensional complex matrices. We investigate how the projections of the DW shell vary with operating points and how this variation can guide the search for worst-case operating conditions. We further propose an efficient algorithm to compute the stability margin and construct the certified operating regions. The effectiveness of the proposed method is validated through case studies on single-converter and 54-converter wind power systems.

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arXiv2026

Negative Resistance Caused by Intra-Loop Coupling in Virtual-Admittance-Based Grid-Forming Control

This paper addresses the harmonic instability problem of the virtual-admittance (VA)-based grid-forming control. It is revealed that the intra-loop coupling among the VA control, the inner-loop current control, and the voltage feedforward control results in an $s^2$-term in the equivalent output impedance of the inverter, which induces a negative-resistance property in the harmonic range. It is worth highlighting that this negative resistance is independent of the control delay. Consequently, this harmonic instability mechanism is fundamentally different from the extensively investigated cases in the literature, which are induced by the digital control delay of inverters. Then, a simple passivity-oriented damping control is proposed to mitigate the negative resistance arising from the intra-loop coupling. The method fully retains the well-established current controller and voltage feedforward, and does not require grid impedance information. Finally, experimental tests verify the theoretical findings and the effectiveness of the damping method.

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arXiv2026

Efficiency and Cost Optimization of Dual Active Bridge Converter for 350kW DC Fast Chargers

This study focuses on optimizing the design parameters of a Dual Active Bridge (DAB) converter for use in 350 kW DC fast chargers, emphasizing the balance between efficiency and cost. Addressing the observed gaps in existing high-power application research, it introduces an optimization framework to evaluate critical design parameters,number of converter modules, switching frequency, and transformer turns ratio,within a broad operational voltage range. The analysis identifies an optimal configuration that achieves over 95% efficiency at rated power across a wide output voltage range, comprising seven 50 kW DAB converters with a switching frequency of 30 kHz, and a transformer turns ratio of 0.9.

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arXiv2026

Experimental Advances on Light Baryon Spectroscopy at BESIII Experiment

The BESIII experiment is currently the world's only electron-positron collider operating in the tau-charm physical energy region. Since starting data taking in 2009, BESIII has accumulated the world's largest data set in the center-of-mass energy range of 1.84-4.95 GeV, including approximately 10 billion $J/ψ$ events and 3 billion $ψ(3686)$ events, together with extensive data on open-charm hadron pair production near threshold regions. These unique datasets, characterized by high statistics and low background, provide unprecedented experimental conditions for studying light baryon spectroscopy. This article systematically reviews the progress made by BESIII in baryon spectroscopy, with a focus on recent breakthrough achievements, including the discovery of excited nucleon states, $Λ$ hyperon states, $Σ$ hyperon states, $Ξ$ hyperon states and $Ω^{-}$ hyperon states. These results expand the spectrum of baryon excited states and provide crucial experimental support for understanding non-perturbative QCD and resolving the ``missing baryon resonances'' problem.

hep-ex↗

arXiv2026

Dr.Sai: An agentic AI for real-world physics analysis at BESIII

High Energy Physics (HEP) experiments like BESIII produce petabyte-scale data. Extracting physics results requires complex workflows (simulation, reconstruction, statistical analysis, etc.) that traditionally take experts months or years. Current manual methods are labor-intensive, prone to bias, and limit large-scale systematic scans. As data grows, this paradigm slows discovery. Large Language Models (LLMs) offer a solution. Their natural language understanding and code generation capabilities allow them to interpret scientific tasks and integrate with HEP tools (e.g., ROOT, BOSS) to act as an "AI partner" for autonomous analysis. We present Dr.Sai, an LLM-powered multi-agent system that translates natural language into rigorous physics workflows. As validation, Dr.Sai performed large-scale re-measurements of ten J/psi decay branching fractions - without manual coding. It successfully navigated the real BESIII computing environment and produced results matching established benchmarks. The article details Dr.Sai's architecture, the validation results, and performance evaluation. This work provides a blueprint for autonomous discovery, with relevance to other data-intensive fields like astronomy and genomics.

hep-ex↗

arXiv2026

A Data-Driven Optimal Control Architecture for Grid-Connected Power Converters

Grid-connected power converters are ubiquitous in modern power systems, acting as grid interfaces of renewable energy sources, energy storage systems, electric vehicles, high-voltage DC systems, etc. Conventionally, power converters use multiple PID regulators to achieve different control objectives such as grid synchronization and voltage/power regulation, where the PID parameters are usually tuned based on a presumed (and often overly-simplified) power grid model. However, this may lead to inferior performance or even instabilities in practice, as the real power grid is highly complex, variable, and generally unknown. To tackle this problem, we employ a data-enabled predictive control (DeePC) to perform data-driven, optimal, robust, and adaptive control for power converters. We call the converters that are operated in this way DeePConverters. A DeePConverter can implicitly perceive the characteristics of the power grid from measured data and adjust its control strategy to achieve optimal, robust, and adaptive performance. We present the modular configurations, generalized structure, control behavior specification, inherent robustness, detailed implementation, computational aspects, and online adaptation of DeePConverters. High-fidelity simulations and hardware-in-the-loop (HIL) tests are provided to validate the effectiveness of DeePConverters.

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arXiv2026

Analysis and Enhancement of Incremental-Quantity-Based Distance Protection With Grid-Forming Inverters

Grid-forming (GFM) inverters are expected in future inverter-dominated grids. In such grids, time-domain protection schemes, for example those based on instantaneous incremental quantities (IQs), are being advocated as potential solutions to the challenges faced by traditional phasor-based protection schemes, due to their ability to process nonlinear data. However, IQ-based protection uses the superposition principle; thus, linearity is still assumed in their application, while GFM inverters are nonlinear sources during faults. This paper proposes an analytical model to study the impact of GFM inverters on the relay-measured IQs. The model is validated with PSCAD/EMTDC simulations, and is used to investigate the interoperability of time-domain IQ-based distance protection with GFM inverters employing different current limiters. Results show that time-domain IQ-based distance protection demonstrates superior dependability for close-in faults compared to that of quadrilateral distance protection with GFM inverters, and it has the possibility to be secure for external faults when quadrilateral distance protection overreaches; however, tuning of its settings is hard to generalize for various sources and faults. Taking the observed interoperability issues into account, a trip criterion for dependable and secure time-domain IQ-based distance protection is proposed, which facilitates easy-to-tune and general settings for applications with GFM inverters.

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arXiv2026

Colloquium: Hadron Production in Open-charm Meson Pair at $e^+e^-$ Collider

The standard model of particle physics is a well-established theoretical framework, yet several unresolved issues remain that warrant further experimental and theoretical exploration. In the realm of quark physics, these issues include understanding the nature of quark confinement and elucidating the mechanism linking quarks and gluons to strongly interacting particles within the standard model theory, which may offer insights into the underlying physics mechanisms. These issues inquiries can be addressed through the study of hadrons produced at $e^+e^-$ collisions and decaying to open-charm meson pairs utilizing the capabilities of {\it BABAR}, Belle, BESIII, and CLEO-c experiments, which have yielded valuable insights into nonstandard hadrons in recent decades. This Colloquium examines the contributions of $e^+e^-$ colliders from the {\it BABAR}, Belle, BESIII, and CLEO-c experiments to such studies in the past two decades and discusses future prospects for $e^+e^-$ collider experiments.

hep-ex↗

arXiv2026

Search for Charmonium(-like) states decaying into the $Ω^-\barΩ^+$ final states

Recently, the BESIII experiment performed a measurement of the energy-dependent Born cross section and the effective form factor for the $e^+e^-\toΩ^-\barΩ^+$ reaction at center-of-mass energies ranging from 3.4 to 4.7 GeV. A fit to the energy dependence of the dressed cross section is performed. With the assumption of a charmonium (like) resonance [i.e., $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $Y(4230)$, $Y(4360)$, $ψ(4415)$, or $Y(4660)$] plus a power-law function, the fit is applied to the data from the recent BESIII measurement, which was additionally combined with previous CLEO-c measurement data. No significance is found. The products of the branching fraction and the two electronic partial widths for the assumed charmonium(-like) states decaying into the $Ω^-\barΩ^+$ final states are also provided. In addition, by taking the world average values of the electronic branching fraction, the branching fractions for $ψ(3770)$, $ψ(4040)$, $ψ(4160)$, $ψ(4415)$ decaying into $Ω^-\barΩ^+$ final states at the 90\% confidence level are determined for the first time. These are found to be at least an order of magnitude larger than expected from predictions using a scaling based on the observed electronic widths.

hep-ex↗

arXiv2026

FAIR-ESI: Feature Adaptive Importance Refinement for Electrophysiological Source Imaging

An essential technique for diagnosing brain disorders is electrophysiological source imaging (ESI). While model-based optimization and deep learning methods have achieved promising results in this field, the accurate selection and refinement of features remains a central challenge for precise ESI. This paper proposes FAIR-ESI, a novel framework that adaptively refines feature importance across different views, including FFT-based spectral feature refinement, weighted temporal feature refinement, and self-attention-based patch-wise feature refinement. Extensive experiments on two simulation datasets with diverse configurations and two real-world clinical datasets validate our framework's efficacy, highlighting its potential to advance brain disorder diagnosis and offer new insights into brain function.

cs.CV↗

arXiv2026

A Review of Hyperon Physics at BESIII Experiment

The BESIII Collaboration has collected large data samples from $e^+e^-$ collisions at center-of-mass energies ranging from 1.84 to 4.95 GeV, which include the world's largest charmonium sample, consisting of 10 billion $J/ψ$ and 3 billion $ψ(3686)$ events. These high-statistics datasets enable BESIII to carry out a wide range of studies in hyperon physics. In this article, we review the major achievements of the BESIII Collaboration in this field, which can be broadly categorized into four areas: hyperon polarization and $CP$ violation, rare hyperon decays, hyperon pair production, and hyperon-nucleon interactions.

hep-ex↗

arXiv2025

LV-CadeNet: A Long-View Feature Convolution-Attention Fusion Encoder-Decoder Network for EEG/MEG Spike Analysis

The analysis of interictal epileptiform discharges (IEDs) in magnetoencephalography (MEG) or electroencephalogram (EEG) recordings represents a critical component in the diagnosis of epilepsy. However, manual analysis of these IEDs, which appear as epileptic spikes, from the large amount of MEG/EEG data is labor intensive and requires high expertise. Although automated methods have been developed to address this challenge, current approaches fail to fully emulate clinical experts' diagnostic intelligence in two key aspects: (1) their analysis on the input signals is limited to short temporal windows matching individual spike durations, missing the extended contextual patterns clinicians use to assess significance; and (2) they fail to adequately capture the dipole patterns with simultaneous positive-negative potential distributions across adjacent sensors that serve as clinicians' key diagnostic criterion for IED identification. To bridge this artificial-human intelligence gap, we propose a novel deep learning framework LV-CadeNet that integrates two key innovations: (1) a Long-View morphological feature representation that mimics expert clinicians' comprehensive assessment of both local spike characteristics and long-view contextual information, and (2) a hierarchical Encoder-Decoder NETwork that employs Convolution-Attention blocks for multi-scale spatiotemporal feature learning with progressive abstraction. Extensive evaluations confirm the superior performance of LV-CadeNet, which outperforms six state-of-the-art methods in EEG spike classification on TUEV, the largest public EEG spike dataset. Additionally, LV-CadeNet attains a significant improvement of 13.58% in balanced accuracy over the leading baseline for MEG spike detection on a clinical MEG dataset from Sanbo Brain Hospital, Capital Medical University.

cs.CV↗

arXiv2025

Comparison of Droop-Based Single-Loop Grid-Forming Wind Turbines: High-Frequency Open-Loop Unstable Behavior and Damping

The integration of inverter-interfaced generators introduces new instability phenomena into modern power systems. This paper conducts a comparative analysis of two widely used droop-based grid-forming controls, namely droop control and droop-I control, in wind turbines. Although both approaches provide steady-state reactive power-voltage droop characteristics, their impacts on high-frequency (HF) stability differ significantly. Firstly, on open-loop (OL) comparison reveals that droop-I control alters HF pole locations. The application of Routh's Stability Criterion further analytically demonstrates that such pole shifts inevitably lead to OL instability. This HF OL instability is identified as a structural phenomenon in purely inductive grids and cannot be mitigated through control parameter tuning. As a result, droop-I control significantly degrades HF stability, making conventional gain and phase margins insufficient for evaluating robustness against parameter variations. Then, the performance of established active damping (AD) is assessed for both control schemes. The finding indicates that AD designs effective for droop control may fail to suppress HF resonance under droop-I control due to the presence of unstable OL poles. Case studies performed on the IEEE 14-Bus Test System validate the analysis and emphasize the critical role of HF OL instability in determining the overall power system stability.

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arXiv2025

Light Baryon Spectroscopy at BESIII

The BESIII collaboration has collected large data samples in the center-of-mass energy range from 1.84 to 4.95 GeV. These data provide a low-background environment and suitable phase space for studying the spectroscopy of light baryons. In this article, we review the achievements of baryon spectroscopy studies by the BESIII collaboration. Most of the results are obtained through the partial wave analysis (PWA) method, with spin and parity well determined.

hep-ex↗

arXiv2025

Impact of Grid-Forming Inverters on Protective Relays: A Perspective for Current Limiting Control Design

Grid-forming (GFM) inverters can significantly alter the fault characteristics of power systems, which challenges the proper function of protective relays. This paper gives a holistic analysis of the interaction between GFM inverter-based resources (IBRs) and the supervising elements in protective relays, including directional and phase selection elements. It is revealed that the current limiting control (CLC) that is based on the current reference saturation method, adversely affects the performance of supervising elements that rely on the negative-sequence quantities. In contrast, adopting highly inductive virtual impedance in the CLC enables a reliable operation of such elements. This finding provides insights into the design of CLC for GFM IBRs from a protection perspective. It is further found that even with a highly inductive virtual impedance, the altered virtual impedance dynamics introduced by the CLC can still lead to malfunctions of the incremental quantity-based supervising elements. These theoretical findings are corroborated by simulations and controller hardware-in-the-loop (CHIL) tests.

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arXiv2025

A Protection-Interoperable Fault Ride-Through Control for Grid-Forming Inverters

Differing from synchronous generators (SGs), grid-forming inverter-based resources (GFM-IBRs) exhibit rapid variations in their output impedances during transmission line faults due to the overcurrent limitation. As a result, the source dynamics during the fault period deviate significantly from those under pre-fault conditions. This fundamental difference alters the fault responses of incremental quantities, thereby jeopardizing the reliability of the supervising elements in protective relays that are based on these quantities. To address this challenge, a protection-interoperable fault ride-through (FRT) method for GFM-IBRs is proposed. This method dynamically adjusts power control of GFM-IBRs in response to the changes in output impedance, effectively mitigating variations in source dynamics and thereby preserving the reliability of incremental quantity-based supervising elements. This method also ensures effective overcurrent limitation and transient stability of GFM-IBRs. Controller hardware-in-the-loop (CHIL) and experimental tests validate the effectiveness of the proposed method.

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arXiv2025

Analysis of Power Swing Characteristics of Grid-Forming VSC System Considering the Current Limitation Mode

This paper investigates power swing characteristics of grid-forming voltage source converter (GFM-VSC) systems considering the current limitation mode in both non-inertial and inertial GFM-VSC systems. Following grid faults, non-inertial GFM-VSC systems can re-synchronize with the grid but may experience significant power swings driven by its control dynamics, while inertial GFM-VSC systems may exhibit loss of synchronization (LOS), characterized by the divergence of the output angle in the active power control loop. These behaviours are different from conventional synchronous generator (SG)-based systems, where power swings are typically characterized by physical angle deviations among power sources. Based on these findings, this paper explores the performance of traditional impedance-based swing detection schemes in GFM-VSC systems. The theoretical analysis is validated through various simulations using the PSCAD/EMTDC platform, covering both single and multi-machine system scenarios.

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