arXiv subjects

Xiao-Bing Zhang

Publications and source records attributed to Xiao-Bing Zhang.

12 recordsLinked to original sources

arXiv2026

Bidding strategies for energy storage players in 100% renewable electricity market: A game-theoretical approach

Large-scale energy storage is expected to be a pivotal source of flexibility in electricity systems supplied entirely by renewable energy sources (RES). However, its strategic role in market-based dispatch remains insufficiently understood. In a 100% RES market setting, storage can improve adequacy and renewable utilization by shifting energy across time. It can also acquire market power as the main flexible, price-making technology. In this paper, we develop a Cournot competition model in which storage operators choose quantity bids to maximize profit in a stylized day-ahead electricity market supplied only by RES. Market clearing is represented through residual-demand blocks so that renewable intermittency appears as an intertemporal arbitrage opportunity for storage operators. We formulate the storage operators' problem in two tractable ways: i) a continuous reformulation based on demand blocks, and ii) an equivalent mixed-integer linear programming (MILP) model with big-M linearization. Nash equilibria are computed with an iterative best-response procedure and benchmarked against a centralized social planner problem to quantify efficiency losses from strategic behavior. The model is calibrated to Denmark's DK1 bidding zone using 2024 day-ahead data and 2030 renewable-capacity and demand projections. The results show that storage reduces imbalances and improves welfare relative to a no-storage case. Concentrated ownership also creates incentives to withhold flexibility, raise prices, and slow the reduction of unmet demand and curtailment. These findings position storage as both a stabilizing resource and a potential source of market power, highlighting the importance of market designs that jointly consider competition, concentration, and capacity deployment in high-RES systems.

econ.GN↗

arXiv2026

Feature-driven reinforcement learning for photovoltaic in continuous intraday trading

Sequential intraday electricity trading allows photovoltaic (PV) operators to reduce imbalance settlement costs as forecasts improve throughout the day. Yet deployable trading policies must jointly handle forecast uncertainty, intraday prices, liquidity, and the asymmetric economics of PV imbalance exposure. This paper proposes a feature-driven reinforcement learning (FDRL) framework for intraday PV trading in the Nordic market. Its main methodological contribution is a corrected reward that evaluates performance relative to a no-trade baseline, removing policy-independent noise that can otherwise push reinforcement learning toward inactive policies in high-price regimes. The framework combines this objective with a predominantly linear policy and a closed-form execution surrogate for efficient, interpretable training. In a strict walk-forward evaluation over 2021-2024 across four Nordic bidding zones (DK1, DK2, SE3, SE4), the method delivers statistically significant profit improvements over the spot-only baseline in every zone. Portfolio experiments show that a pooled cross-zone policy can match zone-specific models, while transfer-learning results indicate a two-cluster market structure and effective deployment in new zones with limited local data. The proposed framework offers an interpretable and computationally practical way to reduce imbalance costs, while the transfer results provide guidance for scaling strategies across bidding zones with different market designs.

cs.LG↗

arXiv2017

Magnetic-induced condensate, vortices and vortons in color-flavor-locked-type matter

By considering Higgs modes within the Ginzburg-Landau framework, we study influences of a rotated magnetic field on the color-flavor-locked-type matter of dense QCD. We demonstrate, in a model-independent way, that a diquark condensate may be triggered by the magnetic response of rotated-charged Higgs modes, in addition to the known color-flavor-locked condensate. Moreover, the condensate is applied to explore formations of vortices in the presence of external magnetic fields. The superfluid-like vortices are constructed for the magnetic-induced condensate. In the situation including both kinds of condensates, the theoretical possibility of vortons is suggested and the formation condition and the energy stability are investigated semi-classically.

hep-ph↗

arXiv2011

Bose-Einstein condensation in strong-coupling quark color superconductor near flavor SU(3) limit

Near the flavor SU(3) limit, we propose an analytical description for color-flavor-locked-type Bardeen-Cooper-Schrieffer (BCS) phase in the Nambu Jona-Lasinio (NJL) model. The diquark behaviors in light-flavor and strange-flavor-involved channels and Bose-Einstein condensation (BEC) of bound diquark states are studied. When the attractive interaction between quarks is strong enough, a BCS-BEC crossover is predicted in the environment with color-flavor-locked pairing pattern. The resulting Bose-Einstein condensed phase is found to be an intergrade phase before the emergence of the previous-predicted BEC phase in two-flavor quark superconductor.

hep-ph↗

arXiv2007

Note on color neutral solutions of the $K^0$ condensed color-flavor locked phase

In the presence of nonzero strange quark mass $m_s$, we investigate color neutrality in the $K^0$ condensed phase of color-flavor locked quark matter. By treating the $m_s$ effects on both kaon condensate and Fermi-surface phenomenon self-consistently, we develop a new treatment to evaluate color neutral solutions within the model-independent framework. It is pointed out that, in the general sense, the expectation values of gluon fields obtained from dynamics of Goldstone bosons solely are not identified with the factual color chemical potentials.

hep-ph↗

arXiv2006

Formation of Gapless Phases of $K^0$ Condensed Color-Flavor Locked Superconducting Quark Matter

Electric and color neutral solutions, and the critical conditions for the formation of gapless color superconductors, are investigated in $K^0$ condensed color-flavor locked quark matter for nonzero strange quark mass. We show that as the strange quark mass increases, gapless modes for up-strange quark pairing occur first, followed by down-strange quark pairing. The behavior of the gaps, the dispersion relations, and the thermodynamic potential are all found as functions of the strange quark mass on the basis of a Nambu Jona-Lasinio type model. To a high degree of accuracy, they are presented as relatively simple elementary functions. This allows for easy computation for any reasonable range of baryon chemical potential and strange quark mass.

hep-ph↗

arXiv2006

Gapless formation in the $K^0$ condensed color-flavor locked quark matter : a model-independent treatment

The electric/color neutral solution and the critical conditions for gapless formation are investigated in the $K^0$ condensed color-flavor locked matter. We point out that there exist no longer gapless modes for down-strange quark pairing while the gapless phenomenon for up-strange one is dominated in the $K^0$ condensed environment. In a model-independent way, the phase transition to the resulting gapless phase is found to be of first-order. The novel phase structure implies that the chromomagnetic instability happens in the previous-predicted gapless phase might be removed at least partly.

hep-ph↗

arXiv2005

Density dependence of quark masses and stability of color-flavor locked phases

Considering the density dependence of quark masses, we investigate the color-flavor-locked matter and its stability relative to the ( unpaired ) strange quark matter. We find that, when the current mass of strange quark $m_s$ is small, the strange quark matter remains stable for the moderate baryon densities. When $m_s$ is large, the gapless phase of the color-flavor-locked matter is found to be difficult to be stable. A schematic phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed in comparison with the previous results.

hep-ph↗

arXiv2005

Effects of density-dependent quark mass on phase diagram of three-flavor quark matter

Considering the density dependence of quark mass, we investigate the phase transition between the (unpaired) strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We find that if the current mass of strange quark $m_s$ is small, the strange quark matter remains stable unless the baryon density is very high. If $m_s$ is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.

hep-ph↗

arXiv2005

The $K^0$ condensed phase of color-flavor locked quark matter : its formation as a stable state reexamined

Taking the vector kaon-quark interaction into account, we reexamine in detail the neutral kaon condensation in color-flavor locked quark matter. It is found that the pairing phenomena in the quark matter are somewhat influenced by $K^0$ condensation. Different from the previous predictions, we find that the $K^0$ condensed phase might no longer be more stable than the normal phase even if $K^0$ condensation can occur in the color-flavor locked matter.

hep-ph↗

arXiv2002

Strange sea asymmetry in nucleons

We evaluate the medium effects in nucleon which can induce an asymmetry of the strange sea. The short-distance effects determined by the weak interaction can give rise to $δm\equiv Δm_s-Δm_{\bar s}$ where $Δm_{s(\bar s)}$ is the medium-induced mass of strange quark by a few KeV at most, but the long-distance effects by strong interaction could be sizable.

hep-ph↗

arXiv2001

Asymmetry of Strange Sea in Nucleons

Based on the finite-temperature field theory, we evaluate the medium effects in nucleon which can induce an asymmetry between quarks and antiquarks of the strange sea. The short-distance effects determined by the weak interaction can give rise to $δm\equiv Δm_s-Δm_{\bar s}$ where $Δm_{s(\bar s)}$ is the medium-induced mass of strange quark by a few KeV at most, but the long-distance effects by strong interaction are sizable. Our numerical results show that there exists an obvious mass difference between strange and anti-strange quarks, as large as 10-100 MeV.

hep-ph↗