bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical analysis of the aspect ratio effect on mixed convection in vertical channels asymmetrically heated with nanofluids with assisting and opposing moving plate
Authors: Buonomo Bernardo , Manca Oronzio , Nardini Sergio , Sarli Gianluca
Published: December 2024

In this study, a numerical investigation on mixed convection in vertical channel with water-alumina (Al2O3) nanofluids due to the interaction between a buoyancy-driven flow and a moving plate-induced one in a vertical channel is performed. One of the plates that bound the channel is heated by a constant heat flux, while the other, considered adiabatic, moves with a constant velocity in the direction of the buoyancy force or in the opposite direction, with a comparison between the two options. The nanofluid is modelled using the Single-Phase Model. The thermophysical properties are assumed to be constant with temperature, and the fluid flow is considered laminar and incompressible. The governing equations are numerically solved with the finite volume method by means of the ANSYS-FLUENT code. The channel can have three different aspect ratios, ranging between 5 to 20, while the two external reservoirs allow simulating the external ambient and assigning a velocity of zero and the ambient temperature at the boundary of the reservoirs. The impacts of the different values of aspect ratio of the channel, wall heat flux, moving plate velocity, and concentration of the nanoparticles are investigated. Results in terms of temperature and velocity are provided. Finally, correlations for predicting of the average Nusselt number along the heated plate are proposed.
Estimating the minimum ignition energy of spark-ignited fuel/air mixtures: preliminary steps towards a novel modelling approach
Authors: Pretto Marco , Betta Enrico De , Giannattasio Pietro
Published: December 2024

In spark-ignition (SI) engines, the achievement of a fast combustion with low cycle-to-cycle variation is highly dependent on the successful initiation of a flame kernel from the spark plug. Its growth can be sped up by increasing the electrical energy supply, but at the cost of higher plug wear, whereas too little energy may result in an ignition failure. Therefore, knowledge of the minimum ignition energy (MIE) of a fuel/air mixture is of key importance to guarantee a proper combustion process at minimal cost. To model the MIE several approaches have been proposed in literature, primarily derived from the experiments conducted by Lewis and Von Elbe and their resulting theory of quenching distances. However, these approaches appear in conflict with more recent experimental outcomes, and the impact of the ignition device is neglected. This work proposes a novel approach for modelling the MIE, which is based on a flame kernel expansion model recently proposed in another paper. In this approach, the proposed model, which has general validity, is specialized to the particular case of the estimation of the MIE, supplied via an electrical breakdown. A model advancement is also included that consists in the quantification, albeit at a preliminary level, of the impact of different gap distances and spark plug quenching effects on the flame kernel development. The results are validated against literature models and experimental data for two fuels, propane and hydrogen, and multiple equivalence ratios. In contrast with the noticeable MIE overestimation of literature models, for propane the proposed approach leads to better results compared to the experiments. Instead, for hydrogen a tendency towards a MIE underestimation is observed, especially for lean mixtures. The model is also tested for SI-engine-relevant conditions, showing satisfactory overall trends. The key source of error seems related to the very complex kernel-electrode interaction, the modelling of which will be improved in future developments.
Chemical kinetics calculation of H2 Laminar Flame Speed: assessment of the performance of public available mechanisms at engine relevant conditions
Authors: Baudone Antonio Denny , Madia Manuel , Pavan Nicolò , Cordisco Ilario , Patrizi Veronica , Marini Alessandro
Published: December 2024

The laminar flame speed (LFS) of actual fuels is a critical property to consider when approaching the computational fluid dynamics (CFD) simulation of turbulent flame propagation in internal combustion engines. A significant gap persists between the conditions under which LFS can be measured and the engine conditions, particularly in terms of pressure and temperature, at high loads in high-specific power engines. Chemical kinetics simulations can be employed to calculate LFS at high pressures and temperatures by using mechanisms that cannot, however, be validated under such conditions due to the unavailability of experimental data. In this study, a literature review was conducted to identify measured values of H2 LFS to be compared with calculated ones through chemical kinetics simulations, using various published chemical schemes. A methodology is developed to assess the reliability of the tested mechanisms for CFD engine simulations, considering more relevant experimental data at higher pressures and temperatures, low dilution, and near-stoichiometric conditions. At low pressures and temperatures (i.e. at part-load engine conditions), all the considered chemical mechanisms yield similar results consistent with those of the Verhelst correlation. However, as the physical conditions move toward a high-load representative one, the choice of chemical scheme for LFS calculation can significantly impact the prediction of turbulent flame speed in actual engines, leading to non-negligible discrepancies.
Experimental and numerical analysis of a waste-gated turbine for automotive turbocharged engine
Authors: Cordalonga Carla , Usai Vittorio , Marelli Silvia
Published: December 2024

This work presents the results of an experimental campaign focused on the steady state behaviour of a waste-gated turbocharger turbine for spark ignition engine. In a first step, the turbine behaviour under different openings of the waste-gate valve is analysed through an experimental campaign performed at the test rig for components of propulsion systems of the University of Genoa.

Based on this experimental activity, a specific numerical model is developed to study the interaction between the rotor channel and the waste-gate valve.

A 1D schematization of the experimental test rig is implemented within the commercial GT-Power code, including the turbine, the waste-gate valve, and the upstream and downstream circuits. In the turbine schematization, the “wheel-map”, estimated by means of the 1D software, is utilized.

A preliminary tuning is carried out based on the turbine characteristic map measured with the waste-gate valve in the fully closed position. Then, the influence of various positions of the by-pass valve on the definition of turbine characteristic curves is investigated under steady flow condition.

A refined model of the waste-gate system reveals to be necessary to correctly reproduce the swallowing capacity of the by-pass port. The waste-gate model is tuned against the experimental findings for a completely closed turbine wheel and various settings of the waste-gate valve.

Finally, once the 1D models of the turbine and of the waste-gate system are independently tuned, their behaviour under parallel flow is analysed. The proposed numerical and experimental results demonstrate the mutual interaction of the two components. In addition, it is highlighted that the turbine and the waste-gate circuit cannot be considered as two systems working in parallel under the same pressure ratio, as usually assumed in 1D codes.
Experimental analysis of the performance of a turbocharger compressor under pulsating flow condition
Authors: Nannetti Federico , Usai Vittorio , Cordalonga Carla , Marelli Silvia
Published: December 2024

To achieve zero CO2 emissions in the transport sector, hydrogen internal combustion engines (H2 ICE) appear to be one of the most promising solutions, particularly for heavy-duty applications. Achieving low NOx emissions requires ultra-lean combustion, which necessitates the use of high air-to-fuel ratios. To obtain this result, suitable boosting systems are required. This study aims to understand the behaviour of a turbocharger compressor. The performance of the compressor is strongly influenced by the unsteady flow generated by the motion of the engine’s intake valves. Achieving a more accurate prediction of engine performance in simulation models requires a deeper understanding of the pulsating flow performance. This understanding can be obtained through measurements conducted in specialized test facilities using appropriate measuring equipment. All the analyses reported in this paper take place at the Test Bench for Components of Propulsion System of the Department of Mechanical, Energy, Management and Transportation Engineering (DIME) of the University of Genoa. Following a short description of the instrumentations adopted, the actual experimental layout, the results obtained from the investigations on the compressor, operating under both steady and unsteady flow conditions, are outlined. The tested turbocharger compressor is coupled to the automotive engine intake circuit, where pulsating flow is generated by a motor-driven cylinder head. Different levels of turbocharger and camshaft rotational speeds are analyzed. For each operating condition, the unsteady performance of the compressor is assessed by measuring several instantaneous parameters, including inlet and outlet static pressure, mass flow rate, and turbocharger rotational speed. Furthermore, the effects of the intake circuit and its interaction with the compressor is deeply analyzed. In particular, the energy content associated with the pulses generated by the intake valves motion is taken into account, considering the hysteresis loops on the compressor map.
Impact of Ozone Addition to Gasoline Surrogates Combustion in Spark Ignition Engine
Authors: Anaclerio Fabio , Camporeale Sergio Mario , Magi Vinicio , Fornarelli Francesco
Published: December 2024

Based on the experimental results, a 3-D Computational Fluid Dynamics investigation is carried out to evaluate the influence of ozone on the combustion process in spark ignition engine fueled with gasoline/air mixtures. Ozone (O3) is a chemically reactive species capable of improving the laminar flame speed, reducing the ignition delay time, and stabilizing combustion variability. With the aim of proposing a 3-D numerical model to simulate combustion of fuel mixtures under ultra-lean conditions, two numerical correlations are proposed to reproduce the chemical properties of gasoline/air/ozone mixtures in terms of laminar flame speed. A chemical kinetic mechanism for Toluene Reference Fuel oxidation (iso-octane, n-heptane, toluene, 63/20/17% by mol.) modified with an ozone sub-mechanism is used to perform several 1-D numerical simulations. The laminar flame speed correlation estimates an enhancement of 3.4% at 600 K and 10 bar under ultra-lean condition (ϕ = 0.6). For the 3-D numerical simulations, the G-Equation model is used to reproduce the premixed combustion process in internal combustion engines. The results suggest that the numerical correlations can predict the combustion properties of gasoline/air mixtures without and with ozone addition. The presence of ozone traduces in a higher laminar flame speed, leading to an increase in the in-cylinder pressure peak and the rate of fuel consumption. Furthermore, the numerical analysis reveals that the greatest improvement is observed for fluid regions within the cylinder characterized by low turbulent flame speed.
Two-phase flow pattern recognition inside tubes by a novel diagnostic technique
Authors: Amoresano A. , Barrasso M. , Langella G. , Quaremba G. , Dedes M. , Iodice P.
Published: December 2024

A two-phase (liquid-gas) flow represents a highly complex regime influenced by factors such as the mass flow rate of each phase, fluid dynamic and thermal conditions, viscosity, density, and surface tension. The presence and distribution of bubbles within the liquid phase significantly impact heat transfer mechanisms and the performance of components like pumps, valves, and nozzles. This study aims to develop and validate a method for identifying the flow regime within a horizontal duct and accurately quantifying flow parameters. The authors have developed a sensing methodology and instrumentation capable of detecting and analysing the vibrational modes of ducts. This approach enables the identification of flow patterns and serves as a sensor for two-phase flow in Direct Steam Generation (hereafter DSG) solar fields. In the experimental by regulating the pump’s rotational speed, inlet gas pressure, and volumetric flow rate, various two-phase flow configurations were replicated. The flow patterns were characterized using independent statistical indices such as crest factors, shape factors, medians, and modes, to define an objective function capable of describing bubble cluster behaviour on a phase diagram (Poincare map), in which more than 76 % of cases were correctly processed. This analysis employs Poincare’s topological theory and the “within-between approach” in multivariate analysis.
Model-based improvement of a trans-critical CO2 refrigeration plant
Authors: Fatigati Fabio , Battista Davide Di , Carapellucci Roberto , Cipollone Roberto
Published: December 2024

Refrigeration sector including heat pumps, cryogenics and air conditioning is responsible for a share close 10% of the global greenhouse gas emissions. Therefore, a huge effort of the scientific and industrial community is needed on the development of technologies allowing to reduce the environmental impact of this sector. The use of CO2 as working fluid has great interest in food chain conservation and participates to the problem of the impact produced by the traditional synthetic fluids, recently oriented also to hydrocarbons. Main problem of plants using CO2 as working fluid is the low COP, which reduces even more in moderate or hot climate regions in which low temperature thermal energy is more required. To assess the benefits introduced by plant optimization and innovative technologies, many advanced thermodynamic models are developed in the last years. Anyway, few software platforms are developed for the comprehensive analysis of plant behaviour. To fill this gap, this paper presents the results of a theoretical and experimental research done on an industrial trans-critical CO2 refrigeration plant. The aim was to set up energy saving solutions finalized to mitigate the intrinsic low COP values. A detailed physically consistent model of the unit has been developed following an integrated zero and mono-dimensional thermo-fluid-dynamic approach. The propagative, capacitive, and inertial properties of the components have been considered, so going beyond of the theoretical approaches that are typical in the sector. A wide experimental characterization of the unit has been done with the aim to validate the model and to use it as tool to predict the effect on the COP of the operating variables. The reduction of the compressor absorption and the potentiality of the energy recovery from energy usually wasted have been analysed.
Solar-Powered Refrigeration for Sustainable Refrigerated Transport
Authors: Petruzziello Fabio , Cilenti Claudio , Grilletto Arcangelo , Maiorino Angelo , Aprea Ciro
Published: December 2024

Solar-powered refrigeration systems offer a feasible and promising solution for enhancing the sustainability of refrigerated transportation. This paper provides a comprehensive overview of the design and construction of a solar-powered refrigeration unit tailored for a refrigerated van, featuring photovoltaic (PV) panels mounted on the rooftop of the refrigerated box. The key components and operational mechanisms of the unit are also highlighted.

The study reports on five preliminary experimental tests conducted to validate the feasibility and efficacy of a transport refrigeration unit (TRU) powered by solar energy. These tests demonstrate the impact of the PV solar system on the energy balance of the refrigerated unit under various environmental and operational conditions. The results indicate that the photovoltaic system enables autonomous operation of the refrigeration unit for 2.5 hours at a set point of -18°C (suitable for frozen products) and over 5 hours at +4°C (suitable for fresh products), assuming afternoon deliveries starting at 14:00 with climatic conditions typical of June and July in Fisciano, Salerno, Italy. These findings support the feasibility of sustainable regional and inter-regional transportation. The study also evaluates the effect of different starting times, revealing an increase in the duration of autonomous operation by up to 35% for transportation at 0°C when the start time is shifted from 14:00 to 11:00.

Furthermore, the research assesses emission savings, identifying reductions between 4.1 and 4.4 kgCO2,e per delivery at set point temperatures of -18 °C and +4 °C, respectively. This range is even wider when considering earlier starting time (up to 5.4 kgCO2,e per delivery in the tests performed). This underscores the significant potential of solar-powered solutions in advancing the decarbonization of the cold chain.

This research aims to inform policymakers and technology developers about the potential of deploying solar-based solutions in the refrigerated transport sector.
Energy flexibility potential associated with thermal uses in prototypes of Italian single-family buildings.
Authors: Zangheri Paolo , Previtali Nicholas , Franchini Giuseppe
Published: December 2024

The transition towards renewable distributed generation and the electrification of consumption will increasingly enhance energy flexibility strategies aimed at promoting self-consumption, energy sharing, and optimizing grid operation. Residential thermal loads can also contribute to these objectives, and this study aims to provide new insights in this regard. The study, based on dynamic load simulation, extends to three types of building-system setups (existing, renovated, and nearly zero-energy) in three climatic contexts (Milan, Rome, and Palermo). Characterization of the flexibility potential associated with building thermal inertia is based on appropriate indicators (Flexibility Index and Peak Load Reduction Factor) comparing consumption profiles associated with two types of internal temperature setpoint control: standard and flexible. The latter is modelled predictively, based on a penalty curve and predicted climatic conditions. Two penalty datasets are considered to represent the perspectives of the energy distributor (DSO) and the operator of a Renewable Energy Community (CER) with photovoltaic installations. The results show how the technological characteristics of building structures can influence the building’s flexibility potential. The greatest benefits are observed during the heating phase and in renovated buildings, which manage to ensure good load shifting capability and significant peak load reduction (up to 60-80%). It is interesting to note that in more efficient buildings, a large portion of flexibility potential can be achieved through energy efficiency solutions, even without flexible control.
Enhancing the prediction of electric load demand: a comparative analysis of ARIMA and ANN models for the case of a small touristic island
Authors: Galli Claudio , Superchi Francesco , Bianchini Alessandro
Published: December 2024

Accurate prediction of energy demand is necessary for efficient power system operation, particularly in energy systems with high renewable sources integration. This study compares different methods for predicting load demand using statistical regression. In particular, the goal is to provide insights on the differences between simpler AutoRegressive Integrated Moving Average (ARIMA) and more complex Artificial Neural Network (ANN) models. The algorithms are used to predict electric load demand in Tilos, a small Greek island with strong seasonal trends due to summer tourism. The case study is significant as Tilos’ outdated electrical grid must adapt to an increasing share of renewable energy sources, making load forecasting increasingly important. The algorithms were developed in Python using open-source tools (such as StatsModels and TensorFlow). Hyperparameters’ tuning, crucial for enhancing forecasting effectiveness, was performed using stochastic optimization with Differential Evolution to minimize RMSE. The optimal normalized RMSE was reported as 9.72% for ANN and 9.54% for ARIMA, showing the effectiveness of both methods, with a slight edge for the statistical model. This work provides critical information regarding load prediction methodologies, highlighting practical guidance for energy managers, policymakers, and researchers in power system planning and operation.
Estimating the solar potential of the rooftops of the city of Genova through the 3D modelling of the built environment and anisotropic tiled sky analysis
Authors: Memme Samuele , Lepore Davide , Priarone Antonella , Fossa Marco
Published: December 2024

In the present paper, the problem of the determination of yearly insolation and photovoltaic (PV) producibility of a series of selected suburbs located in the city of Genova (region Liguria), Italy is tackled through the GIS based construction of the 3-dimensional built environment and proper modelling of hourly solar energy availability. The input data include local climate conditions, as inferred from local hourly insolation data as 12-year averages of global and diffuse irradiance data from PV-GIS-SARAH platform. The built environment is described in terms of raster files having resolution 0.5m able to provide the 3D coordinates of building volumes, infrastructures and terrain surfaces, as kindly provided by the city of Genova municipality. The solar yield analysis is carried out by building a cumulative 3D tiled sky starting from TMY (typical metereological year) of the present location, taking into account the hourly distribution of beam and diffuse solar radiation all year round. The calculations of the building surface view factors towards the sky elements is performed within the QGIS platform by using python scripts able to calculate the superposition of reflected to direct irradiance while taking into account the mutual position of roof portions and sky dome radiating tiles. The analysis is performed also considering the near and far obstacle shadings (near buildings, far mountains). Statistical processing of selected suburbs rooftop portions showed that up to 60% of building roof are exposed to an yearly insolation above 1200 kWh/m2/yr, thus potentially able to fulfil the expected demand of PV energy of the entire Liguria at the year 2030.
Energetic and exergetic analysis of an AE-T100 micro gas turbine system fuelled by partially cracked ammonia
Authors: Monacchini Chiara , Anfosso Chiara , Bellotti Daria , Magistri Loredana
Published: December 2024

In recent years, ammonia has gained attention as a fuel for power generation purposes, especially due to its chemical characteristics which ensure reaching the target of zero-carbon emissions. Ammonia is also a powerful hydrogen carrier, with a solid and consolidated production method based on the Haber-Bosh process. By exploiting the ease of transport of ammonia that is liquid at moderately low pressures and temperatures, it can be converted to hydrogen and nitrogen through a cracking reaction directly at the power production plant site. Moreover, to reduce greenhouse gas emissions (GHG) in the production energy sector, small-scale power generation systems are today gaining more attention. In this context, the use of partially cracked ammonia mixtures in micro gas turbine fields represents an interesting solution in the distributed generation sector. In this work, an energetic and exergetic analysis of an AE-T100 mGT fuelled by partially cracked ammonia mixtures is carried out. The analysis has been performed by varying the ammonia cracking percentage according to the maximum achievable conversion by exploiting the thermal energy contained in mGT exhaust gases. The whole system has been modeled in MATLAB/Simulink environment and it includes not only the turbine but also the ammonia conditioning system required to bring the ammonia at the condition imposed by the mGT. Moreover, a comparison with the mGT fuelled by conventional fuel is carried out both from a thermodynamic and exergetic point of view.
Experimental characterization of the acoustic response of cavity-backed perforated plates to control thermo-acoustic instabilities in gas turbines
Authors: Bourgeolet Clément , Ceglie Vito , Laera Davide , Stefanizzi Michele , Camporeale Sergio Mario
Published: December 2024

Prediction and control of thermoacoustic instabilities is a major challenge in the development of modern power generation gas turbines and aeroengines. Such instabilities arise from the coupling between flame dynamics and combustor acoustic modes, resulting in severe oscillations that can lead to premature aging of combustor components and structural damage. In many combustors, passive dampers are implemented to increase the acoustic energy dissipation of the system and prevent the onset of these harmful flame-acoustic interactions. In the present study, passive damping systems based on a cavity-backed perforated plate are experimentally analyzed, with a focus on studying the impact of bias flow on the reflection coefficient over a wide range of frequencies. Tests are carried out on two cavity-backed perforated plates characterized by the same porosity but a different number of holes 25 and 49, namely P25 and P49, respectively. It is observed that, for a given plate geometry, a higher bias flow leads to an increase in the plates absorption capacity over a wider range of frequency. This is more pronounced in the P
49 plate configuration. For both tested configurations, comparing the experimental results with Scarpato model proposed in the literature [1], a good match it is observed only for low values of bias flow. The model instead is not able to correctly capture the behavior of the damping systems when higher dissipation is reached.
Sensorless PMSM control system design based on XMC1302
Authors: Zhang Kohao , Zhao Xin , Lu Xuewei , Zhou Hongqiang
Published: December 2024

Addressing the issues of insufficient torque, low efficiency, and limited speed regulation in traditional constant frequency ratio control of Permanent Magnet Synchronous Motors (PMSM), this paper designs a PMSM control system based on the XMC1302 microcontroller. The study focuses on how to achieve smooth speed regulation from 500 rpm to 5000 rpm without position sensors. By incorporating a rotor state estimation algorithm, the motor’s performance is significantly improved across a wide speed range. This research offers crucial theoretical and practical insights for achieving efficient and stable operation of PMSM under sensorless control.
Research on the joints of second-generation high-temperature superconducting tape
Authors: Xing Mingtian , Zhi Tengfei , Wang Luoyuan
Published: December 2024

The second generation of high-temperature superconducting tape (REBCO) joint technology is of great significance to the development of high-temperature superconducting magnets. Tape joints are indispensable for the development of magnets, and it is of great significance to study and improve the welding technology of tape joints to reduce the resistance of the joints and the heat load generated for the operation of superconducting magnets. In this paper, a number of YBCO superconducting joints are prepared by the welding process, using two kinds of solder, under the conditions of different welding temperatures, lap lengths, and thicknesses of solder, in order to study the effects of different process parameters on the resistance of the welded joints.
Design of thermal management system for high-power liquid-cooled charging pile
Authors: Wang Junqiang , Yang Shuqiang , Liu Yike , Tang Yingguo
Published: December 2024

High-power ultra-fast charging causes the charging gun to rapidly heat up, posing safety hazards. Therefore, the focus of the research is on thermal management during the overcharge process. To address this, a novel thermal management control system (TMS) for high-power liquid-cooled charging piles has been designed. The liquid circulation channels connect the cables and the charging gun, with coolant flowing through the pipes. A pump delivers the coolant to the charging gun to remove heat. The TMS monitors temperature, pressure, and flow to control the oil pump and fan speeds, maintaining the perforating gun temperature within a preset range and managing the system’s heat. This TMS system enables the liquid-cooled charging cables to carry larger currents, significantly enhancing charging power.
H∞ state feedback design based on LQR robust control for inverted pendulum system
Authors: Hu Weitao , Wang Yuxuan , Pang Aiping
Published: December 2024

This paper proposes a robust H∞ design method for the disturbance suppression of an inverted pendulum. Based on the LQR method, the H∞ state feedback design, which has good robustness and disturbance rejection, is provided. The H∞ state feedback problem is ultimately converted into the resolution of the Riccati equation. The key to solving the Riccati equation is how to determine the weighted matrix in the H∞ controller. This paper takes the effective bandwidth of the system, the requirements of high properties at low-frequency ranges, and the coordination between variables and other aspects into consideration, which successfully solves the many parameters’ selection problem. And the physical significance is clear. The outcomes indicate that the advanced H∞ state feedback control scheme, rooted in LQR robustness, significantly enhances the system’s capability to mitigate external interference.
Study on the effect of seasonal permafrost on soil resistivity
Authors: Yue Keyu , Zheng Yu , Zhao Hongdan , Gao Guangmin
Published: December 2024

In order to study the effect of seasonal permafrost on soil resistivity, firstly, the resistivity influencing factors were analysed, the soil conductivity model was established, and the effects of permafrost on soil resistivity and the number of freeze-thaw cycles on soil resistivity at different depths were analysed through simulated experimental measurements. The results show that the freeze-thaw cycle will lead to soil structure damage, internal loosening, current conduction is blocked, and resistivity increases; with the rise in the number of freeze-thaw cycles, the soil is gradually solidified, the current conduction is enhanced, and the resistivity gradually decreases and tends to be stabilised; beyond the freezing depth of the soil, the resistivity tends to be stable, almost unaffected by the freeze-thaw cycle. Moreover, in a single freeze-thaw cycle, the effect of freezing on soil resistivity gradually increases as the freezing temperature decreases.
Study on the phenomenon of nonlinear variation of VeE-max during aging of multichip parallel IGBT modules
Authors: Wang Zhichao , Meng Zhaoliang , Gao Yong
Published: December 2024

The aging failure of bonding wires in IGBT modules is one of the causes of module failure, and it is one of the contents of the reliability research of power electronic devices and systems to investigate the damage mechanism, evolution law, and condition monitoring method of module bonding wires. In this paper, by taking the Infineon FF450R12ME4 half-bridge IGBT module as an object, we designed a double-pulse test to verify the correlation between the module junction temperature and VeE-max, used artificial picking off the bonding wires to simulate the aging of bonding wires, and analyzed the evolution law of VeE-max during the aging process. The results show that there is a good linear relationship between VeE-max and junction temperature, which can be used as a temperature-sensitive electrical parameter to predict the junction temperature. In the aging process of bonding wire, the change rule of VeE-max is different from that of traditional single-chip IGBT modules, showing a nonlinear trend. This nonlinear variation rule provides a new reference for the reliability assessment and bonding wire condition monitoring of the module.
An intelligent diagnosis method for transformer based on CSSA-MCKD
Authors: Wang Liyu , Qin Jinfei , Chen Chunyu , Zhao Dawei , Lu Yixiang
Published: December 2024

In transformer fault diagnosis, the difficulties of signal feature extraction under strong noise backgrounds and the low accuracy of acoustic signal diagnosis still need to be effectively addressed. For this purpose, this paper proposes a novel transformer fault diagnosis model. The model combines an improved Sparrow Search Algorithm optimized Maximum Correlation Kurtosis Deconvolution (MCKD) with a Bi-directional Long Short-Term Memory Neural Network (BiLSTM). Firstly, to address the issue of the traditional Sparrow Search Algorithm falling into local optima, this study introduces an improved cubic chaotic mapping for initializing the population, compared to the traditional uniform distribution, this method more effectively enhances the diversity of the population, thereby improving the algorithm’s global search capability and convergence speed. Secondly, considering that the decomposition performance of the MCKD method is highly dependent on the choice of its main parameters, an improved Sparrow Search Algorithm is used to optimize these parameters, thereby enhancing the accuracy and stability of the signal decomposition. Finally, to address the issue of weak signal features in strong noise environments, this study uses optimal MCKD to perform denoising and feature enhancement on the raw data, thereby eliminating redundant interference and improving the robustness and accuracy of the diagnostic network. This paper validates the effectiveness of the proposed algorithm through comparative experiments with signal simulation and measured data.
An optimal configuration scheme of virtual capacity expansion transformers considering short-term emergency load capacity
Authors: Guo Qiang , Chen Weijun , Yao Haiyan , Li Zhonghua , Zhang Xufeng , Bian Yang , Sun Qingqi
Published: December 2024

As critical equipment for electrical energy transmission and voltage transformation, power transformers are fundamental to the power grid’s safe, reliable, and economical operation. As urbanization accelerates, the contradiction between the lag in constructing power transformers and the urgent need for short-term capacity expansion becomes increasingly prominent. Existing capacity expansion methods present challenges such as high costs and significant space requirements. In order to solve the problem, this paper proposes an optimized configuration scheme for virtual capacity expansion transformers, which considers the short-term emergency load capacity. Firstly, an annual average cost model of a virtual capacity expansion transformer is proposed. Then, the optimal configuration scheme is established with the highest average effective utilization rate of the transformer and the lowest comprehensive economic cost index as the optimization goal. Finally, a 220/110 kV urban power grid system is simulated to prove the advantages of the proposed scheme compared with the existing scheme.
A dynamic state evaluation method for current sensors based on reference values and time series
Authors: Zhou Ke , Meng En , Mo Zhiyue , Jin Qingren , Bao Haibo
Published: December 2024

Due to the complex and ever-changing power environment, when designing dynamic state evaluation methods for current sensors, there is often a problem of inaccurate calculation of state evaluation values, leading to poor evaluation accuracy of the methods. A dynamic state evaluation method for current sensors based on reference values and time series is proposed. Firstly, we normalize the time series data of the current sensor, construct a covariance matrix, calculate the degree of correlation between the time series data, and construct a higher quality current sensor state dataset. Then, we select multiple indicators as state evaluation indicators and quantify them. Then, the feature vector of the evaluation indicators and the state evaluation value are calculated. Under the influence of the reference value, we set the threshold of the current sensor in different states to divide the current sensor into different states. Through the above design, the dynamic state evaluation method for current sensors is completed. The experimental results show that the designed dynamic state evaluation method for current sensors based on reference values and time series has an average coefficient of determination of 0.95 in practical applications, with high evaluation accuracy.
Transformer winding state diagnosis method based on short-circuit impulse response and multi-feature joint
Authors: Chen Yuwen , Sun Qiuya , Huang Yijun , Zhang Feng , Qian Xingxu
Published: December 2024

To investigate the relationship between the physical characteristics of transformer short-circuit impulse signals and winding deformation, this paper proposes a transformer winding state diagnosis method based on the combination of short-circuit impulse response and multiple features. Firstly, based on the relative displacement model of a single degree of freedom system, a winding short-circuit impulse response spectrum is constructed, and the energy entropy characteristics of different frequency bands are extracted using the Hilbert energy spectrum. Secondly, the energy spectrum is converted into a time-frequency matrix, and its energy density distribution and short-term energy attenuation changes are quantified. Then, we perform support vector regression (SVD) decomposition and calculate the proportion of singular value vectors. Finally, multiple feature quantities are combined to construct a feature set, which is then input into the SVD model optimized by the particle swarm algorithm (PSO) for diagnosis. The experimental results show that the proposed method can accurately extract the physical characteristics of short-circuit impulse signals, and the error between the obtained transformer winding deformation diagnosis value and the actual state value is only 3.6%, which can provide guidance for online monitoring of the transformer winding state.
Online monitoring method for inter-turn short circuit fault of dry-type hollow core reactor
Authors: Tang Zhen , Huang Yijun , Sun Qiuya , Yao Hongyang , Qian Xingxu
Published: December 2024

A method for online monitoring of turn-to-turn short circuit faults based on power factor changes is proposed to solve the problem of small overall current changes and delayed overcurrent protection after the occurrence of turn-to-turn short circuit faults in dry-type hollow reactors. A circuit model of inter-turn short-circuit fault reactor was established, and the changes in electrical parameters of the fault reactor were numerically analyzed at different positions. On this basis, the power factor was determined as the monitored variable, and a test platform was built for experimental verification. The research results indicate that after a turn-to-turn short circuit fault, the total current changes very little, the power factor increases significantly, and the changes in various electrical parameters are related to the location of the short circuit. The experimental results are consistent with the theoretical analysis results, verifying the correctness and effectiveness of the monitoring method.
Microwave-based passive wireless electronic transformer development
Authors: Wang Yu , Zhu Jianyang , Qiu Keyue , Dai Qiji , Mao Junyi , He Yumin
Published: December 2024

With the continuous development of intelligent substations and the past demand for intelligent transformation of power grids, electronic transformers have been widely utilized. Given that the active type of electronic transformer was susceptible to electromagnetic interference, particularly on the high-voltage power supply side, disturbances were challenging to evade, leading to its poor reliability. Based on microwave wireless transmission technology, this study theoretically proposed a dynamic wireless energy supply link for electronic transformers and designed a passive wireless electronic transformer utilizing microwave technology. Simultaneously, it developed the corresponding software and hardware systems, constructed an experimental test platform, conducted tests in high-voltage environments, and verified its performance by comparing it with active wired methods. The results demonstrated that the microwave-based passive wireless electronic transformer developed in this paper had good reliability and could be widely applied in practice.
Optimal scheduling of microgrids based on IWSA
Authors: Zhang Shuai , Xianyu Jianchuan
Published: December 2024

Microgrid systems are usually composed of multiple distributed power sources. Smart algorithms are often used to schedule microgrids to reduce operating costs. Smart algorithms are prone to fall into local optimal solutions when solving microgrid scheduling models, resulting in poor solution accuracy. Therefore, based on the white shark algorithm, a mixed-strategy improved white shark algorithm (WSA) is proposed, which improves the white shark optimization algorithm by using three strategies, including Tent chaotic mapping, nonlinearly adjusted convergence factor, and Cauchy variants. The method is designed to ensure that the operation of microgrids achieves the best results in terms of economy by satisfying various system constraints. It is found that the improved algorithm has great improvement in convergence speed, convergence accuracy, and stability, which proves its effectiveness.
Optimal carbon reduction and energy storage management method for new power systems considering carbon emissions
Authors: Liang Shen , Chu Xueli , Wang Peng
Published: December 2024

With the advancement of the national “dual carbon” strategy goals and the planning of new energy systems, the proportion of new energy connected to the power grid is rapidly increasing. Therefore, it is urgent to accelerate the planning and construction of energy storage. In this context, from the perspective of energy storage as a regulatory resource, this paper aims to build a set of energy storage state estimation and residual life prediction methods with high estimation accuracy and low computational complexity and achieve energy storage management on the energy storage management system of edge computing architecture, so as to meet the safe, reliable, lasting and efficient operation needs of the energy storage management system, while promoting wind and solar energy consumption as a means. Taking carbon emission reduction as the optimal goal, energy storage management and utilization methods are built. Through simulation experiments, it is verified that this optimal carbon reduction and energy storage management method has good experimental results.
A new low carbon scheduling method for source load multi time scale in power systems
Authors: Zhao Fei , Yang Li , Chen Jiaxi , Gu Jiting , Pan Li
Published: December 2024

The impact of global climate change caused by carbon dioxide emissions on human production and life is becoming increasingly severe. New energy sources, led by wind and solar power, have become the backbone of reducing carbon emissions. The main focus of this article is to develop advantages such as multi-energy complementarity, efficient integration, flexibility and stability, and low-carbon environmental protection. While meeting the diverse energy needs of the energy consumption side, it is necessary to reasonably allocate resources on the energy supply side and effectively absorb renewable energy. To begin with, this paper develops a multi-time-scale economic dispatch model for a holistic energy system, focusing on collaborative carbon reduction between energy sources and loads. The upper layer serves as a long-term energy scheduling mechanism, dynamically updating electricity prices and conveying them to the lower layer model. The lower layer functions as a short-term energy scheduling component, directing load management according to electricity prices and providing feedback on the load plan to the upper layer model. Both the upper and lower-layer models strive to minimize the overall operational costs as their primary objective. Secondly, the probability distribution of wind and photovoltaic power is discretized using sequence operation theory. The CPLEX is used to solve the above model. Finally, taking a comprehensive energy system as an example, the impact of source load side carbon reduction measures on the system scheduling results under multiple time scales is analyzed.
Analysis and prediction of distribution network load characteristics based on data mining
Authors: Ye Peng , Yuan Yingzhi , Na Zheng , Liu Jun , Li Shiyu , Liu Anqi
Published: December 2024

Load forecasting helps the power department make annual, scheduling, and maintenance plans. In this paper, we take the distribution network of Shenyang as the research object, use the spectral clustering algorithm to cluster the load data, and analyze the correlation between the load and external factors through the correlation and gray correlation method. Moreover, we use the BO - TPE - XGBoost model for load forecasting and compare it with other methods. The results show that this method significantly improves the forecasting accuracy.
Distributed transaction method for multi-energy systems clusters considering uncertainties in photovoltaic power output
Authors: Huang Liuqiang , Huang Yan , Qin Lijuan , Deng Wenli , Hu Jianmin
Published: December 2024

In light of the emerging trend of distributed transactions within the multi-energy system(MES) cluster, this paper proposes a distributed transaction method for MES that takes into account the uncertainties in photovoltaic (PV) power output. This approach aims to achieve optimized resource scheduling within the MESs, as well as coordinated optimization of transactions between different MESs. Firstly, the uncertainties in PV power output within the MES are addressed using the distributionally robust chance constraint. Subsequently, the optimization problem of the MES cluster is decomposed using the alternating direction multiplier method, thereby establishing a distributed transaction model for the MES cluster that considers PV power output uncertainties. Finally, the case study demonstrates that the proposed model can balance the individual interests of each MES with the overall interests of the MES cluster. It effectively reduces the operating costs of the MESs and determines optimal operation strategies for them.
Decentralized optimization for multi-microgrid systems via enhanced concurrent alternating direction method of multipliers
Authors: Zheng Siyuan , Xiang Yejun , Wu Longdong , Sun Jingliao , Meng Jian , Huang Qifei
Published: December 2024

In microgrid systems, the diversity of power sources, limitations in network communication, and the growing emphasis on privacy protection for power generation equipment present significant challenges to traditional centralized dispatch methods. Within a system comprising multiple microgrids, a comprehensive assessment is conducted, taking into account the operational costs of conventional power generation units, the curtailment costs associated with renewable energy generation, and the depreciation costs of energy storage systems. Based on the distribution of power generation units and energy storage devices within the grid, a decentralized dynamic economic dispatch framework is established. Leveraging this groundwork, we have introduced a well-conceived and practical partitioning scheme specifically designed for the multi-microgrid landscape. An improved synchronous computational Alternating Direction Method of Multipliers (ADMM) is proposed, which, by exchanging only voltage phase information between adjacent areas during each iteration, enables parallel economic dispatch calculations across regions. This approach significantly enhances solution efficiency while ensuring overall optimization. Tested on a real-world microgrid case, the results validate the accuracy and practicality of the algorithm.