Suzhou Institute of North China Electric Power University

This paper proposed a new approach combining priority list (PL) with binary particle swarm optimization (BPSO) to solve unit commitment (UC) problem. At first, PL method was used to determine the initial UC, and then the optimization window was determined according to the results, at last the BPSO method was adopted to solve the UC problem within the window. The window is to reduce the computing time and improve the optimization accuracy. In each iteration, the adjustment heuristic strategy was applied to revise the particle to meet the generators' constraints. This paper adopted Lambda-iteration method combining with dichotomy algorithm to solve the economic dispatch (ED) problem. The simulation results showed that the proposed method is indeed capable of obtaining higher quality solutions.

Abstract In order to solve the collaborative optimization scheduling of multi‐microgrid under the high penetration rate of new energy, this paper considered the energy interaction between micro‐grids in multi‐microgrid and the relationship between new energy consumption and electricity cost, constructed a collaborative scheduling model considering both micro‐grid load and main grid wind and optical energy storage, proposed objective function based on economic cost, and improved Genetic Algorithm (GA). The elite thought and catastrophe thought are used to optimize the selection operation, and the particle swarm optimization algorithm is used to optimize the mutation operation. Furthermore, three scenarios were selected to verify the effectiveness of the proposed model and the improved GA. The results show that the proposed model can ensure the stable operation of the multi‐microgrid system with a high proportion of new energy access and reduce the operation cost. In addition. the improved algorithm solves the problems of easy to fall into local optimum and slow iteration speed, and has better performance in solving the model.

The high percentage of branched units with different structures leads to the complex pyrolysis chemistry and product distribution of hemicellulose. In this study, four main branched monosaccharides, i.e., arabinose (Ara), galactose (Gal), galacturonic acid (GacA), and glucuronic acid (GlcA) were employed as typical xylan-based hemicellulose model compounds. The pyrolysis behaviors and mechanisms of these monosaccharides were deeply explored by the combination of pyrolysis experiments and density functional theory (DFT) calculations. Particularly, the roles of structural differences of these monosaccharides were carefully analyzed. Due to the uronic acid group, GacA and GlcA were easier to decompose, having two weightloss peaks with close intensity, and the release of CO2 had greater intensity than Ara and Gal pyrolysis at low temperatures. GlcA with the equatorial hydroxyl group can undergo a special CC bond breaking reaction to depart the C6 uronic acid group to release HCOOH. The fast pyrolysis of these monosaccharides obtained similar product species but distinct relative contents. The structure of an uncertain hydromethyl-furnaose product was identified as 5-(hydroxymethyl)furan-3(2H)-one (5-HMFO) by combined DFT calculations and experimental results. The findings of this work are beneficial to gain a deep understanding of the pyrolysis chemistry of hemicellulose, especially the role of different branches.

Abstract Carbon capture, utilization and storage (CCUS) is a critical technology option in achieving large‐scale CO 2 mitigation for power and industrial sectors. A full‐chain CCUS cluster could be formed based on numerous scattered capture sources and one or more storage sites connected by a pipeline network. Reasonable source‐sink matching planning for a full‐chain CCUS cluster could substantially reduce the system overhead. However, most of the previous studies could hardly address the dynamic source‐sink matching planning problem of a full‐chain CCUS cluster with multiple types of emission sources and sinks during multiple periods. Therefore, the objective of this study is to investigate an optimized source‐sink matching scheme within a CCUS cluster through developing an optimization‐based CCUS source‐sink matching model. The proposed model is based on multistage mixed integer linear programming techniques with the objective of least‐cost strategy; thus, it can deal with dynamics of capacity expansion associated with CCUS activities. The developed method is then applied to a CCUS cluster facing long‐term dynamic planning issues. The modeling results suggest that the optimization‐based CCUS source‐sink matching model is applicable in reflecting dynamics of time, scale and location of CO 2 capture, transportation and storage within a CCUS cluster. The obtained solutions can provide decision bases for formulating an optimal planning scheme of a full‐chain CCUS cluster under evolving reduction targets or constraints. © 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.

As a large number of flexible elements such as distributed power and flexible load are connected to microgrids, the economic improvement of microgrids has become an important topic through rational energy distribution. In this paper, an economic scheduling model considering the load demand for a microgrid system under the mechanism of a peak–valley tariff is proposed. A mathematical model of the microgrid components is proposed to determine the exchange power between the microgrid and main network. Meanwhile, an improved War Strategy Optimization (WSO) algorithm is proposed to investigate three scenarios: (i) without batteries, (ii) with batteries and (iii) with batteries and demand response. Additionally, demand response optimization is carried out with the Particle Swarm Optimization (PSO) algorithm and the improved WSO is compared with four other algorithms in scenario (iii). The comparison shows that the improved WSO algorithm has a better optimization performance in solving the proposed scheduling model.

The multi-microgrid is gradually springing up with widespread use of the distributed generation. It is of great meaning to have research on the energy mutual optimization of the multi-microgrid to improve the new energy-consumption capacity. In this paper, a comprehensive economic model of the multi-microgrid is proposed for optimizing the power dispatching, and the source-network-load-storage is taken into account. Different from other studies, the special novelty of this paper is the improved cuckoo search (CS) algorithm which is adopted to optimize the power dispatching of the multi-microgrid. Comparing with the particle swarm optimization (PSO) algorithm, the improved CS algorithm has better performance in solving the proposed model. The optimal power supply strategy is determined by predicting the optimal state of charge of the battery in the model of the multi-microgrid. The model effectiveness of the multi-microgrid is confirmed in the case study of Wangjiazhai area. With this method, the optimal power dispatching is determined.

Fast pyrolysis of biomass to produce bio-oil is an important technology to utilize lignocellulosic biomass, because the liquid bio-oil is regarded as a promising candidate of petroleum fuels. However, bio-oil is a low-grade liquid fuel, and required to be upgraded before it can be directly utilized in existing thermal devices. Catalytic cracking is an effective way to upgrade bio-oil, which can be performed either on the liquid bio-oil or the pyrolysis vapors. Various catalysts have been prepared and used for catalytic cracking, and they exhibited different catalytic capabilities. This paper will review the recent progress of the catalytic cracking of liquid bio-oil or pyrolysis vapors.

An active distribution network is an important development trend of the power grid with widespread use of the distributed generation. The reliability of the active distribution network is not negligible due to the uninterruptible power supply. In the paper, the reliability evaluation method of the active distribution network is proposed in detail, based on combining the roulette wheel selection and the sequential Monte Carlo algorithm. The uncertainty of both the distribution generation and the load is taken into consideration based on the power probability distribution and the working state in the presented model. Furthermore, the IEEE-RBTS Bus 6 is used to verify the validity of the proposed method. The result shows that the new energy access improves the availability and the reliability of the active distribution network.

Nitrogen oxides (NOₓ) are primary pollutants produced during biomass combustion. During the devolatilization stage, char nitrogen (char(N)) is formed. In the subsequent char combustion stage, char(N) can decompose directly into NOx precursors or engage in heterogeneous reactions with O2 or NO to form NO and N2. Nonetheless, a comprehensive understanding of the reaction mechanisms and competitiveness of char(N) migration, especially the influence of the alkali metal potassium (K) present in biomass, remains incomplete. Building on the Zigzag char(N) models, the present study delves into the migration reactions of char(N), assessing their competitive dynamics through the integration of density functional theory, electronic structure analysis, and conventional transition state theory. Furthermore, it examines the impact of K on char(N) conversion. The competitiveness of the heterogeneous reactions follows the sequence: heterogeneous reduction of NO to N2 > heterogeneous oxidation of char(N) to NO > decomposition of char(N) to NOx precursors. Moreover, the formation of HCN is more favorable than NH₃ production. The successive conversion from char(N) to NO and then to N2 is the predominant migration route for char(N), with NO generation as the pivotal step. The less preferred char(N) migration route involves decomposition to NH3/HCN, followed by oxidation to NOx within the main combustion zone, which cannot be mitigated by char. K can accelerate NO generation and sustain the primacy of the heterogeneous NO reduction, consequently enhancing the oxidation-reduction process of char(N). As a result, K plays a constructive role in managing NOx emissions during the thermal conversion of char.

The impact of the upstream and downstream fuel injection ratio on the flame stabilization combustion modes in a cavity-based scramjet was investigated. Three different injection schemes with global equivalence ratio of 0.73 were comparatively researched. The kerosene injection ratios in upstream and downstream regions were 3:1, 1:1, and 1:4. Three typical flame stabilization modes and a transition combustion mode were identified by using multispectral imaging, high-speed framing of CH* chemiluminescence, and wall pressure measurement. The experimental results showed that the cavity shear layer stabilization mode occurred in a combustor with 75% fuel upstream injection ratio. When the fuel upstream and downstream injection ratio was 1:1, the cavity-jet-wake stabilization mode and cavity-assisted shear layer-jet-wake stabilization mode occurred alternately. The proportion of stable combustion area increased by 43.36% and 35.87% compared with the fuel upstream injection ratio of 75% and 20%, respectively. The peak CH* signal region with cavity-jet-wake stabilization mode occurred at the slope of the back edge of cavity and the downstream platform of the cavity. The peak CH* signal region with the cavity-assisted shear layer-jet-wake stabilization mode occurred simultaneously at the shear layer and the slope of the back edge of cavity. With decrease in the fuel upstream injection ratio to 20%, the flame stabilized in the jet-wake. The time-resolved flame temperatures in the case when fuel was injected equally in the upstream and downstream regions were 45 and 221 K higher than those in the cases with ratios of 3:1 and 1:4. The cavity-jet-wake stabilization mode was more beneficial to the operation of the scramjet engine.

A two-layer optimization model and an improved snake optimization algorithm (ISOA) are proposed to solve the capacity optimization problem of wind–solar–storage multi-power microgrids in the whole life cycle. In the upper optimization model, the wind–solar–storage capacity optimization model is established. It takes wind–solar power supply and storage capacity as decision variables and the construction cost of the whole life cycle as the objective function. At the lower level, the optimal scheduling model is established, considering the output characteristics of various types of power supplies and energy storage, microgrid sales, and purchases of power as constraints. At the same time, the model considers constraints, such as the power balance, the operating state of the energy storage system, the power sales and purchases, and the network fluctuations, to ensure the system operates efficiently. Taking a microgrid in South China as an application scenario, the model is solved and the optimal capacity allocation scheme of the microgrid is obtained. Meanwhile, the demand response mechanism and the influence of planning years are introduced to further optimize the configuration scheme, and the impact of different rigid–flexible load ratios and various planning horizons on microgrid capacity optimization is analyzed, respectively, by a numerical example. The comparison shows that the ISOA has better optimization performance in solving the proposed two-layer model.

It has been one of the most effective way to fully develop the Distributed Generation (DG) when it is connected to the main power grid by way of microgrid, supporting each other with the main power grid. The research of the microgrid size and the specification of its acceptable capacity with respect to the main power grid will be beneficial to the best utilization of renewable energy resources, achieving the coordinated development between DG and the main power grid. What's more, this will be a guide and specification for the connection of the microgrid to the main power grid, ensuring operational security, stability, and economical efficiency. This paper started with characteristics of microgrid interconnected system, relative issues when microgrid connected and its impacts upon the main power grid were discussed. Combining with the analysis, means of defining the acceptable capacity of microgrid connected to the main power grid were introduced in this paper. Finally, simulations were carried out using MATLAB/SIMULINK tool, of which the result presented the acceptable capacity of microgrid connected to the main power grid.

This paper presents a new power quality detection method based on the improved HHT in microgrid. Hilbert-Huang Transform (HHT) can distill these disturbing signals automatically and time-frequency spectrum can be obtained. However, in the application of this method there are serious end effects that mixed mode phenomenon will appear, affecting the detecting results. In order to suppress the end effects, the original data is extended by Least Squares Support Vector Machine (LS-SVM). The results show that the improved HHT method is effective to control the end effects and the frequency and amplitude of disturbing signal will be detected quickly and effectively.

The static air gap eccentricity is one of the prevalent faults in permanent magnet synchronous generators. In previous studies, the variation of magnetic flux density, stator current and vibration have been studied mostly. However, the temperature characteristic of winding insulation under 3D static air gap eccentricity fault is rarely investigated. As a supplement, this paper comprehensively analyzes the influence of radial static air gap eccentricity, axial static air gap eccentricity and the combined static air gap eccentricity (radial static air gap eccentricity and axial static air gap eccentricity) fault on the winding insulation thermal response. The whole work is based on not only the loss of core and windings but also the temperature rise of the winding insulation, which is carried out through theoretical analysis, finite element calculation, and experiment verification. It is shown that radial static air gap eccentricity will increase the winding insulation temperature whatever in singe radial static air gap eccentricity or combined static air gap eccentricity, while axial static air gap eccentricity has the opposite effect. Specifically, the winding insulation temperature in radial static air gap eccentricity 0.1 mm, 0.2 mm and 0.3 mm cases are 57.18℃, 59.10℃ and 61.04℃, respectively, which is 3.29℃, 5.21℃ and 7.15℃ higher than that under normal condition. However, under axial static air gap eccentricity, winding insulation temperature will decrease by 1.84℃, 4.11℃ and 5.9℃, respectively. When axial static air gap eccentricity is unchanged and radial static air gap eccentricity is increased, the winding insulation temperature will increase by 1.5℃ and 3.23℃, respectively. On the contrary, when radial static air gap eccentricity is unchanged and axial static air gap eccentricity increases, the winding insulation temperature decreases by 2.54℃ and 5.66℃, respectively. The end part and the join between the end and line parts of the winding insulation are the most dangerous positions to suffer from static thermal wear.

In this paper the significance and several methods of high voltage switchgear temperature monitoring are discussed.Through the comparison of several temperature measuring methods,it introduces the advantages of using optical fiber grating temperature measurement method in switchgear monitoring.The paper designs an on-line monitoring system for the switchgear based on optical fiber Bragg grating(FBG).It explains the system structures of sensing layer,transport layer and monitoring layer and gives the layout way of the FBGs.At last,the paper designs the functions of monitoring software and discusses the key problems needed to be solved.

China’s commitment to decarbonization has become a foundational principle guiding policymaking at national, provincial, and local levels across diverse sectors. This commitment is especially evident in the active promotion of low-carbon energy transitions by all provinces, aligning with the national goal of carbon neutrality. This paper focuses on Ningxia Province and constructs five scenarios for low-carbon energy transition, adopting the multi-level perspective. These scenarios include the business-as-usual scenario (BAU), high electrification scenario (HES), high outward electricity scenario (HOS), low carbon scenario (LCS), and energy saving scenario (ESS). Utilizing the LEAP-Ningxia model, we simulate energy demand across various sectors until 2060. The quantitative analysis covers primary energy production, secondary energy conversion, final energy consumption, and CO 2 emissions. Notably, under scenarios incorporating carbon capture and storage (CCS) and carbon credits, the total CO 2 emissions in Ningxia are projected to decrease to 17∼23 Mt CO 2 until 2060 under BAU, HES, and HOS. In LCS and ESS, a remarkable achievement is forecasted with 6∼93 Mt CO 2 of negative emissions from the energy sector in Ningxia until 2060. The findings underscore the importance of diverse CO 2 reduction measures and their impacts on achieving a zero-carbon energy transition in Ningxia. The implications of scenarios with CCS and carbon credits showcase significant reductions in CO 2 emissions, aligning with China’s broader decarbonization goals. The results provide valuable scientific support and insights for policymakers and stakeholders involved in steering Ningxia towards a sustainable and low-carbon future.

Pyrolysis is an efficient utilization method for S-containing organic solid wastes to produce value-added chemicals and fuels but is accompanied by gaseous pollutants (e.g., H2S and COS). The selective transformation of sulfur to H2S in the pyrolysis gas will be beneficial for the quality improvement of liquid and solid products, as well as the further management of sulfur. However, the S-containing gas formation mechanism, especially the influence mechanism of widely presented alkali metals, is still unclear. Herein, the formation pathways of S-containing radicals/gases (S, SH, CS radicals, and H2S) was investigated by combining density functional theory (DFT), kinetic calculations, and wave function analysis with thiophene as the model compound. The impact of K+ and Na+ on S-containing species formation was carefully studied to elucidate the enrichment method for H2S. Thiophene decomposition is preferentially initialized by the 1,2-hydrogen transfer reaction. The formation competitiveness of S-containing species is in the order SH radical ≈ H2S > CS radical ≈ S radical, indicating the dominance of H2S compared with those of COS and CS2 formed through CS radicals. Alkali metal ions can enhance the decomposition of thiophene and are beneficial to the direct formation of H2S and S radicals through enhanced hydrogen transfer reactions. An inferior generation path of SH radicals is significantly enhanced, and the CS radical formation is inhibited in the presence of K+ and Na+. Consequently, alkali metal ions are conducive to direct and indirect generation and enrichment of H2S in the gas phase. The elucidation of the enhanced H2S formation method can lay a theoretical basis for the waste-to-value utilization of H2S in the pyrolysis gas.

The effects of flight dynamic pressure on plume temperature distribution and heat release characteristics in a kerosene-fueled scramjet were experimentally investigated. The plume radiation intensities, temperature distributions, and wall pressure were measured by employing a multispectral imaging equipment and wall pressure measurement system with flight dynamic pressures of 41 and 85 kPa. The experimental results showed that peak plume radiation intensity for the 85 kPa flight dynamic pressure scramjet was 1.27 × 109 W/m3/sr, with an equivalent ratio (ER) of 0.6, which was 43.3% higher than that with ER = 0.2. The difference in peak plume radiation intensity with ER = 0.2 and 0.6 decreased to 19.6% for the 41 kPa flight dynamic pressure scramjet. The enhancement effect of increasing fuel injection volume on plume propagation stability for the 85 kPa flight dynamic pressure scramjet was better than that for the 41 kPa flight dynamic pressure scramjet. The average plume temperature with a flight dynamic pressure of 85 kPa decreased by 20.2% at the stage of ER switching from 0.4 to 0.6 and by 25.7% when the ER decreased from 0.6 to 0.3 for the expander outlet region. The duration of high plume temperature for expander outlet region was 13.33% less than that for the plume tail region. The plume combustion stability near the expander was easily weakened by the change in ER compared with that near the plume tail. The opposite correlation with ER and wall pressure rise occurred within different flight dynamic pressure combustors. The heat release process was weakened with the increase in ER from 0.4 to 0.6 for the 42 kPa flight dynamic scramjet.

The microgrid technologies provide an efficient way for various distributed generations connected to the grid. However, the inherent characteristics of distributed generation (DG), the special network topology and the operation characteristics of the microgrid bring unfavorable factors influencing power quality of the microgrid, especially power quality disturbances. In this paper, a new detection method on basis of generalized morphological filter and backward difference is proposed. Firstly, the signal was processed by the first generalized morphological filter which was used for prepositive filter unit, then transformed by dq transformation. And then the second generalized morphological filter with the structuring elements of straight line was used to eliminate the noise. Lastly, the disturbance signal was located by using backward difference. MATLAB/SIMULINK is employed for the simulation studies of the method. The simulation results show that the method possesses the merits of simplicity, speediness and accuracy, and meets the requirement of the real-time cases.

A comprehensive understanding of the catalytic decarbonylation mechanism of furfural (FF) is prominently meaningful for developing effective catalysis techniques to produce furan. Herein, possible mechanisms for FF decarbonylation over single-site and multi-site Ni/MgO surfaces were investigated using periodic density functional theory calculations. The electronic structures evidence that Ni doping can modify the electronic density of MgO and thus form favorable electronic configurations for FF adsorption. The reaction paths indicate that the single-site and multi-site catalysts result in different decarbonylation mechanisms of FF, with the latter having better catalytic activity, because the multi-site Ni/MgO has high selectivity in the C–C bond-breaking-induced pathway. Furthermore, potential decarbonylation catalysts doped by diverse metals over the MgO surface were examined. It is proved that Ni/MgO has excellent decarbonylation performance among these transition or noble metal-doped catalysts, and it is even comparable to the Pt/MgO catalyst.