Sulfide compounds provide a type of promising alternative for oxygen evolution reaction (OER) electrocatalysts due to their diversity, intrinsic activities, low-price and earth-abundance. However, ...the unsmooth mass transport channel, the collapse of the structure and insufficient intrinsic activities limits their potential for OER performance. In respond, the dense Fe-doped Co
9
S
8
nanoparticles encapsulated by S, N co-incorporated carbon nanosheets (Fe-Co
9
S
8
@SNC) was proposed and synthesized via fast thermal treatment from ultrathin metal-organic frameworks (MOFs) nanosheets. In designed catalysts, the nanosheet configuration connected by nanoparticles retained rich access for permeation of electrolyte and precipitation of O
2
bubbles during OER process. Meanwhile, the outer carbon layer of Co
9
S
8
provided additional catalytic activity while acting as armor to keep the structure stability. At the atomic scale, the doped Fe regulated the local charge density and the d-band center for facilitating desorption of oxygen intermediates. Benefiting from this multi-scale regulation strategy, the Fe-Co
9
S
8
@SNC displays an ultralow overpotential of 273 mV at 10 mA·cm
−2
and small Tafel slope of 55.8 mV·dec
−1
, which is even close to the benchmark RuO
2
catalyst. This concept could provide valuable insights into the design of other catalysts for OER and beyond.
Highlights
The 2D CoOOH sheet-encapsulated Ni
2
P into tubular arrays electrocatalytic system with expediting mass transport, structural stability, and tuned electron was conceptually proposed.
The ...designed electrocatalysts realize expectant 1000 mA cm
−2
-level-current-density hydrogen evolution in neutral water for over 100 h.
Water electrolysis at high current density (1000 mA cm
−2
level) with excellent durability especially in neutral electrolyte is the pivotal issue for green hydrogen from experiment to industrialization. In addition to the high intrinsic activity determined by the electronic structure, electrocatalysts are also required to be capable of fast mass transfer (electrolyte recharge and bubble overflow) and high mechanical stability. Herein, the 2D CoOOH sheet-encapsulated Ni
2
P into tubular arrays electrocatalytic system was proposed and realized 1000 mA cm
−2
-level-current-density hydrogen evolution over 100 h in neutral water. In designed catalysts, 2D stack structure as an adaptive material can buffer the shock of electrolyte convection, hydrogen bubble rupture, and evolution through the release of stress, which insure the long cycle stability. Meanwhile, the rich porosity between stacked units contributed the good infiltration of electrolyte and slippage of hydrogen bubbles, guaranteeing electrolyte fast recharge and bubble evolution at the high-current catalysis. Beyond that, the electron structure modulation induced by interfacial charge transfer is also beneficial to enhance the intrinsic activity. Profoundly, the multiscale coordinated regulation will provide a guide to design high-efficiency industrial electrocatalysts.
This paper presents an open‐access Matlab/Simulink‐based power system simulation toolbox (MatPSST) for research and education. In MatPSST, dynamic modeling is implemented by Simulink. Only the ...initialization process is coded in Matlab. This structure makes full use of Simulink, enabling users to fully use the rich solvers and built‐in toolboxes in Matlab/Simulink, such as small‐signal analysis, without additional programming. The interaction with real‐time platforms like RTLAB and dSPACE in MatPSST is convenient through the Simulink interface. In addition, MatPSST provides a uniform interface and flexible framework for user‐defined functions. Users do not need to consider the interaction between models and dynamic solvers when implementing state‐of‐the‐art user‐defined models. To avoid the heavy work (replicate units and change parameters) in modeling detailed wind farm or photovoltaic station with hundreds of renewable generation units, the idea of the vector‐variable‐based model is proposed with MatPSST. Case studies introduce some selected application examples of MatPSST in research and education and demonstrate its accuracy by the comparisons with Simscape and PSAT. The cases reveal the advantages of MatPSST in promoting power system research and education.
MatPSST is a Matlab/Simulink‐based toolbox, developed for power system dynamic simulation. Flexible user‐defined function in MatPSST enables users to customize model and build extensible renewable energy plant model. By using existing toolboxes, it reduces extra programming and supports the real‐time simulation platform natively like dSPACE and RTLAB.
With the rapid development of voltage source converter based high-voltage direct current, power flow analysis becomes increasingly important for AC/DC hybrid systems. This study extends the ...holomorphic embedding (HE) method to the VSC-based AC/DC power flow problem. With an appropriate embedding technique, a general embedded model is established for AC/DC power flow with VSCs, which can not only preserve the deterministic property of HE that enables it to derive the desired solution in an explicit manner but also flexibly accommodate various bus types, VSC configurations, control strategies and operating conditions. Moreover, the sparsity of the recursive matrix in power series calculations and the introduction of the iterative calculation of the inverse matrix (ICIM) to rational approximants contribute to the high computational efficiency of the model. The proposed method is shown to be feasible and efficient by illustrative cases and is further extended to multi-terminal (VSC-MTDC) configurations to verify its flexibility.
Probabilistic load flow (LF) calculation is the first step to evaluate the potential impact of the integrated wind power on the power system. Although research works show that the wind speed can be ...modeled by a Weibull probability density function (pdf), due to the nonlinear relationship between the wind speed and the wind power as well as many other influencing factors, it is hard to fit wind power to any common pdfs. At the same time, the relationship between the input and output variables of LF calculation is nonlinear. In view of the two characteristics, the point estimate method and Gram-Charlier expansion method are combined. Based only on the sample data of the wind power, the expectation, variance, and cumulative distribution of the output random variables can be estimated with the method by 2n + 1 times of LF calculation, where n is the number of input stochastic variables, eliminating the need for the distribution of the input variables. The simulation results on the New England Test System and New York Power Pool (NETS-NYPP) system and the actual Northeast China Grid show that the proposed method provides higher precision with less computation burden. The method can also be applied to other problems with uncertainty factors whose distribution is unknown in the power system.
With the increasing amounts of terminal equipment with higher requirements of communication quality in the emerging fifth generation mobile communication network (5G), the energy consumption of 5G ...base stations (BSs) is increasing significantly, which not only raises the operating expenses of telecom operators but also imposes a burden on the environment. To solve this problem, a two-step energy management method that coordinates 5G macro BSs for 5G networks with user clustering is proposed. The coordination among the communication equipment and the standard equipment in 5G macro BSs is developed to reduce both the energy consumption and the electricity costs. A novel user clustering method is proposed together with Benders decomposition to accelerate the solving process. Simulation results show that the proposed method is computationally efficient and can ensure near-optimal performance, effectively reducing the energy consumption and electricity costs compared with the conventional dispatching scheme.
The congest in an open communication system may cause the failure of the load frequency control (LFC) scheme in the power system. Furthermore, the increase of wind power penetration degrades the ...stability of the LFC scheme. To address these two issues, this paper analysis the stability of the LFC schemes with both the Bernoulli model and the Gilbert-Elliott model packet losses based on the Markov jump system. The effect of wind penetration on the stability of the LFC schemes also discussed as inertia reduction. Moreover, the combined action of packet losses and inertia reduction is discussed both in theoretical. Then, a resilient event-triggered LFC scheme is proposed to deal with packet losses and wind penetration. Simulation results with different scale of power systems are given to validate the proposed LFC scheme.
The increasing penetration of renewable generation increases the need for flexibility to accommodate for growing uncertainties. The level of flexibility is measured by the available power that can be ...provided by flexible resources, such as dispatachable generators, in a certain time period under the constraint of transmission capacity. In addition to conventional flexible resources, energy storage is also expected as a supplementary flexible resource for variability accommodation. To aid the cost-effective planning of energy storage in power grids with intensive renewable generation, this study proposed an approach to determine the minimal requirement of power capacity and the appropriate location for the energy storage. In the proposed approach, the variation of renewable generation is limited within uncertainty sets, then a linear model is proposed for dispatchable generators and candidate energy storage to accommodate the variation in renewable generation under the power balance and transmission network constraints. The target of the proposed approach is to minimize the total power capacity of candidate energy storage facilities when the availability of existing flexible resources is maximized. After that, the robust linear optimization method is employed to convert and solve the proposed model with uncertainties. Case studies are carried out in a modified Garver 6-bus system and the Liaoning provincial power system in China. Simulation results well demonstrate the proposed optimization can provide the optimal location of energy storage with small power capacities. The minimal power capacity of allocated energy storage obtained from the proposed approach only accounts for 1/30 of the capacity of the particular transmission line that is required for network expansion. Besides being adopted for energy storage planning, the proposed approach can also be a potential tool for identifying the sufficiency of flexibility when a priority is given to renewable generation.
Base station (BS) backup batteries (BSBBs), with their dispatchable capacity, are potential demand-side resources for future power systems. To enhance the power supply reliability and ...post-contingency frequency security of power systems, we propose a two-stage stochastic unit commitment (UC) model incorporating operational reserve and post-contingency frequency support provisions from massive BSBBs in cellular networks, in which the minimum backup energy demand is considered to ensure BS power supply reliability. The energy, operational reserve, and frequency support ancillary services are co-optimized to handle the power balance and post-contingency frequency security in both forecasted and stochastic variable renewable energy (VRE) scenarios. Furthermore, we propose a dedicated and scalable distributed optimization framework to enable autonomous optimizations for both dispatching center (DC) and BSBBs. The BS model parameters are stored and processed locally, while only the values of BS decision variables are required to upload to DC under the proposed distributed optimization framework, which safeguards BS privacy effectively. Case studies on a modified IEEE 14-bus system demonstrate the effectiveness of the proposed method in promoting VRE accommodation, ensuring post-contingency frequency security, enhancing operational economics, and fully utilizing BSBBs' energy and power capacity. Besides, the proposed distributed optimization framework has been validated to converge to a feasible solution with near-optimal performance within limited iterations. Additionally, numerical results on the Guangdong 500 kV provincial power system in China verify the scalability and practicality of the proposed distributed optimization framework.
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