bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental analysis of thermal behavior of latent heat thermal energy storage coupled to opaque ventilated façade
Authors: Colinart T , Batard M , Fuentes A , Noël H , Glouannec P
Published: December 2023

Opaque ventilated façades are increasingly used in building envelopes due to their potential to reduce summer overheating. During cold seasons, such façades can be used to preheat air before indoor blowing. However, to overcome the mismatch between energy supply and demand, using thermal energy storage may be appropriate. This work investigates the experimental thermal behavior of opaque ventilated façade coupled to latent heat thermal energy storage. The experimental set-up includes a mobile and tilting façade, an air/PCM heat exchanger and a ventilation unit. This system is instrumented with numerous thermocouples, heat flux sensors, mass flow sensors and anemometers. The system is tested in the campus of Université Bretagne Sud (Lorient, France) under various weather and operating conditions. The measurements are analyzed in detail to assess the thermal performance of the system, particularly the energy collected by the façade and the energy stored by the system.
Wind-driven rain tightness of building-integrated photovoltaics panels
Authors: Moschetti R , Gullbrekken L , Asphaug SK
Published: December 2023

The exposure to wind-driven rain (WDR) is a key factor impacting the performance and the durability of the building envelope. Building-integrated photovoltaic (BIPV) panels are increasingly used as roofing and façade materials, but little information is available on their weather protection performance. Although WDR exposure has been qualitatively investigated in laboratories, only few studies have directly quantified the water intrusion through BIPV. This article presents the results from a WDR laboratory test of a BIPV product, where water intrusion was both qualitatively and quantitatively investigated. Furthermore, as roof integration is the primary function of the studied BIPV panels, the results from the same test performed on another traditional roofing material, i.e., concrete tiles, are described and discussed. The test results showed that the BIPV panels performed better as façade cladding than as roofing material, since no quantifiable water leakages were detected at 90° inclination. At 15° and 30° inclinations, the total water leakages through the BIPV system were around 90% lower than those of the concrete tile roofing. This article’s findings demonstrate that the quantification of water intrusion through BIPV panels is feasible and can provide significant information for further developing and improving the design of BIPV systems as climate screens.
Capturing Building Fabric Thermal Performance and Solar Heat Gains Through a Whole House Heat Loss Test – an In-Situ Study in Poland
Authors: Baborska-Narożny Magdalena , Grudzińska Magdalena , Bandurski Karol
Published: December 2023

Determining a building’s “as built” heat loss coefficient (HLC) is one of the key starting points to understand the role of residents’ practices in heating or cooling-related energy consumption. It is also a starting point for white-box modelling of different behaviour scenarios within a given home environment. Co-heating test is a recognised experimental method to evaluate the building’s fabric thermal performance. It involves a quasi-stationary homogeneous heating experiment performed on an unoccupied dwelling. This paper discusses the results of a co-heating test carried out in a low-energy semi-detached house in Wrocław, Poland between 6th-12th December 2021. The periods of different types of solar operation are captured to evaluate HLC: night-time with no solar gains, daytime with direct solar gains, and daytime with only the diffuse component of solar radiation. Internal solar gains in the building are calculated using the TRNSYS simulation program, assuming detailed modelling of the radiation incident on the vertical partitions (including the anisotropy of the diffused radiation component and complex analyses of the sun path geometry inside the building). Based on the results, the HLC values excluding infiltration and ventilation corresponding to different solar operation types are calculated and compared. This contributes to a more nuanced understanding of HLC under different external conditions.
Hygrothermal Performance of simple intensive Green Roofs with Different Irrigation Schemes
Authors: Freudenberg P. , Hänicke P. , Kuzmanovska J.
Published: December 2023

Urban mesoclimate is formed by a multitude of factors enhancing climate change characteristics like increasing temperature levels, reduced air moisture content, atmospheric pollution or extreme rain events. All of these factors could be attenuated by green roof structures. Unfortunately, this potential is not being tapped in current building practice. The majority of erected green roofs are built as extensive, i.e. non-irrigated, types. This results in a poor mesoclimatic impact as the water contents of these roof substrate layers are meagre, and vegetation layers are more or less inactive during the dry, hot summer months. Intensive green roofs, on the other hand, require higher load-bearing capacities and costs, both often not eligible for refurbishments. A promising approach is a combination of simple intensive green roof structures featuring a thin substrate layer with reduced irrigation techniques, especially under the usage of grey water. The hygrothermal performance of these structures in comparison between different irrigation schemes and solar radiation levels is shown in this article. Measurements were performed over a period of about two years. Hygrothermal performance shows the importance of an optimised relationship between irrigation scheme, substrate type and thickness in order to achieve a sufficient evapotranspiration and temperature balancing effect.
Green roof evaluation and comparison during summer in Central Europe climate
Authors: Juras Peter
Published: December 2023

Greening structures, such as roofs or facades, attract the worldwide attention because of their multi-disciplinary benefits. Green roofs are considered to be one of the best ways to eliminate summer overheating, mitigate the climate change or reduce the urban heat island effect. Since 2020, experimental fragments of different green roofs are evaluated on the roof of one building in the university campus. Temperatures are measured within the roof and also in the additional green layers. Also the water retention is measured. In this paper, results of temperature measurements of three different types of protective layer on the single ply flat roof are presented. One is bare, unprotected PVC membrane, the other one is gravel and the third one is an extensive green roof. During the summer season and sunny days the daily amplitudes are reduced from approximately 56°C for the unprotected PVC membrane and 35 °C for the gravel to the 16 °C for the green roof. The gravel slightly reduced the maximum temperatures, but it has an accumulation capacity, which decelerates cooling of the surface and the heat emitted back to surroundings is higher. Water retention is also another benefit, which increases the reduction, but in this analysis the worst scenario with lack of any rainfall for more days was taken into account.
Infrared thermography application for in-situ determination of the building envelope thermal performance
Authors: Moga L , Moga I , Șoimoșan T , Moldovan I , Rădulescu M , Rădulescu A , Iancu I
Published: December 2023

During the phase of creating energy audit documentation, many calculations are needed when evaluating the thermal performance of building envelope components due to a large number of distinct components and junctions. Several computer programs are available to assess buildings’ energy consumption, using the thermal performance of building envelope elements as input data. These thermal performances are often provided with varying degrees of accuracy, typically only for the current field of the component, without considering the impact of thermal bridges. However, when using linear heat transfer coefficients ψ, the details provided in thermal bridges’ atlases do not cover all the case studies encountered in the current design, which often requires approximate details. In some cases, the technical documentation of the building is unavailable, which leads to various assumptions about the detailing of the building envelope and a non-realistic picture of the energy performance of the assessed building. The paper presents a methodology and accompanying software called THERMOG that evaluates the thermal performance of the building envelope under actual operating conditions using aerial and terrestrial thermography methods. The paper presents initial findings from some case studies used to calibrate the developed methodology.
Estimating time-dependent solar gains through opaque building envelope parts: an explorative study on a test box
Authors: Zhang Xiang , Aviv Dorit , Saelens Dirk , Roels Staf
Published: December 2023

Accurate estimation of the energy gain from solar radiation in buildings is necessary for building energy performance characterization, model predictive control (MPC), fault detection and diagnostics, etc. Solar radiation affects the buildings’ internal air temperature dynamics, either (directly) by penetrating the glazing or (indirectly) through the opaque building envelope. Nevertheless, no research has investigated the on-site data-driven modelling of the indirect effects of solar radiation i.e., additional solar gain through the opaque building envelope, marked as indirect solar gain. Therefore, this work aims to develop grey-box model-based techniques to characterize the dynamics of indirect solar gain. A test box, with overall dimensions of 120*120*120 cm3, that represents a simplified scale model of a building is examined, to provide an initial understanding of this matter. This test box is south-north orientated and has only one window of 60*60 cm2, positioned on its southern wall. On-site data associated with this text box was recorded during the summer (June-July) in Almeria, Spain. This simplified reduced-size text box satisfies the research goal very well to serve as a pilot case study, since the indirect solar gain was the dominant effect of solar radiation. Based on the in-situ data from this case, a three-dimensionally decomposed solar irradiance integrated grey-box modelling technique is proposed for characterizing the dynamics of indirect solar gain. Preliminary results from this study show that this technique can effectively reveal the key dynamics of indirect solar gain and outperform the classic grey-box model, based on limited low-frequency on-site measured data.
A holistic sustainability assessment of a zero-emission development in Norway
Authors: Wiik Marianne Kjendseth , González-Fernández Irene , Schneider-Marin Patricia
Published: December 2023

The decarbonisation of the construction sector is critical to meet national and international climate goals. Literature gives many examples of measures for the reduction of greenhouse gas (GHG) emissions from buildings. However, few studies investigate the trade-offs between potentially conflicting GHG emission reduction measures or the affordability of these measures. Ydalir is a Zero Emission Neighbourhood (ZEN) pilot area in the Norwegian research centre for Zero Emission Neighbourhoods in smart cities. One of the major challenges Ydalir faces is how to reduce GHG emissions from the neighbourhood towards a net zero emission building (nZEB). Additional challenges include retaining social, environmental, and economical sustainability for both the project developer and building owners and avoid suboptimal solutions. This paper investigates the trade-offs between energy efficiency and material use for two scenarios. The scenarios are a Norwegian building code scenario and a passive house scenario. The analysis ascertains total energy demand, whole life cycle GHG emissions, and cost assessment for two housing units within Ydalir Torg. The results show lower total GHG emissions and lower GHG emissions from operational energy use in the passive house scenario, and an increase in GHG emissions from the production phase due to thicker levels of insulation. The cost assessment shows increased investment costs for the project developer in the passive house scenario, despite lower operational costs for the building owner. Total GHG emission payback times for the passive house scenario are at 18 - 19 years. Cost payback time varies between 10 - 37 years. This paper is useful for practitioners that wish to balance GHG emission reduction requirements between operational energy use, material use and affordability.
A comparative assessment of the development of GHG emission criteria and benchmark values for buildings in Norway
Authors: Wiik Marianne Kjendseth
Published: December 2023

GHG emission criteria and benchmark values for buildings are being developed internationally to meet climate goals in the Paris agreement. However, there is a distinct lack of harmonisation in approaches making it difficult to compare construction projects or implement and apply benchmarking at a national or international level. Norway is no exception. In recent years, multiple GHG emission criteria and benchmark values have been developed and tested to measure and evaluate the environmental sustainability of Norwegian buildings during their life cycle. These include proposals from Ydalir Masterplan, the research centre for zero emission buildings in smart cities, FutureBuilt ZERO and BREEAM-NOR v6.0. This paper presents and reviews these approaches in relation to recent Norwegian building code requirements for the reporting of GHG emissions. The paper compares the approaches in terms of methodologies, typologies, reference study period, life cycle modules, building parts, limitations and advantages. The results show that there are large differences in approaches which leads to a disparity in benchmarking levels. Further work is required to harmonise and create an accepted branch standard for benchmarking GHG emissions from buildings for the construction industry in Norway. In addition, it would be of benefit to establish a national database for GHG emission accounting so that better benchmark values can be established.
Strategies for Low CO2-emission Schools in Norway
Authors: Felius L C , Brozovsky J , Smits F
Published: December 2023

Regional and national strategies targeting climate change are a driver for reducing greenhouse gas emissions. Municipalities play an important role towards a sustainable society and in restructuring needed to reach the 2030 European Climate targets. They often require that new buildings shall be zero emission and that the building’s carbon footprint shall be reduced compared to a reference building, starting with public buildings. To reach low or zero emission buildings, the production of renewable energy must equal or outweigh the CO2-emissions associated with the building. The energy consumption of the building should be decreased before designing on-site renewable energy generation systems. This is ensured by following a holistic energy design approach: energy conservation, reducing electrical energy, efficient energy management and producing renewable energy. Although Norway has had a focus on low and zero emission buildings, there is a limited number of low CO2-emission schools. These are designed and constructed by various actors. Therefore, the practical experience and knowledge in the industry is scattered and still in development. This paper aims to summarize practical strategies for low CO2-emission schools in Norway. Several case studies were analyzed to identify common traits and interviews were conducted to identify opportunities, challenges and strategies.
Evaluation of the embodied carbon of insulation in achieving a national retrofit plan in Ireland: Probono case study and the national perspective
Authors: Sajadirad F. , O’Hegarty R. , Kinnane O.
Published: December 2023

Overall, the building and construction sector, in Ireland, was responsible for 23 % of final energy use and 37 % of carbon dioxide (CO2) emissions in 2021. Ireland boasts some of the most ambitious targets for Greenhouse Gas (GHG) emission reduction to 2030 in the world. In Ireland, emissions related to the operation of the residential sector receive particular attention, and the government have introduced a National Retrofit Plan that aims to retrofit 500,000 (~25%) of the national housing stock by 2030. However, carbon emissions related to the achievement of this retrofit have not been quantified. This paper aims to outline the initial steps in evaluating the embodied carbon input of achieving a national retrofit plan of this unprecedented scale. Also, it aims to assess the relative carbon savings resulting from the production of materials to achieve retrofit plan. In the first stage, a case study of social housing, used in Probono project within the Dun Laoghaire Rathdown (DLR) local authority of Dublin City in Ireland is investigated as a best practice template for future retrofit projects. The embodied carbon of retrofit is evaluated. Then, a large housing sample set of DLR is evaluated in terms of Building Energy Rating (BER). This sample set is compared with the BER ratings of national stock to evaluate its representativeness. The results indicate that most of the dwellings on the sample set of DLR, in line with the national stock, are C and D rated and need to be retrofit to achieve B rating or better. In the final section, four types of nominal dwellings in Ireland are selected to evaluate the required volumes of thermal insulation and the added embodied carbon of retrofit to reach the national retrofit plan. The results demonstrate that ~30 million m3 of thermal insulation will be required for the national retrofit plan and it will add ~2 MtCO2 of the embodied carbon.
Sound insulation of slabs in dwellings
Authors: Miškinis Kęstutis , Bliudžius Raimondas , Buska Andrius
Published: December 2023

The well-being and sleeping quality of people in dwellings depends on appropriate sound insulation efficiency of building structures. In individual apartments, airborne sound is produced by people talking and music playing, and impact sound is produced by people walking and falling of various objects on the floor. The inter floor slab separating the individual dwellings is intended for airborne and impact noise insulation, so special attention is paid to its design and installation. Since the composition of this structure is primarily determined by the structural requirements, the improvement of the sound insulation performance is mainly carried out by developing the damping interlayer materials. The stone wool plate has been modified reducing the fiber intertwining to obtain a more uniform fiber directivity, thus reducing its dynamic stiffness. Therefore, the aim of this study was to investigate the sound insulation efficiency of inter floor slabs with a new modification of stone wool damping interlayer in comparison with currently used mineral wool products. The experimental measurements in 50-5000 Hz frequency range were performed in construction site (real structures), the single-number quantities – weighted standardized level difference (DnTw) and weighted normalized impact sound pressure level (L‘nW) with living adaption term (C) were determined and compared. The research results demonstrated that the modified stone wool with reduced fiber intertwining and lover organic content used for damping interlayer enables to improve living sound insulation of inter floor slab comparing with existing stone wool materials.
Understanding Discrepancies between predicted and experienced (Dis)comfort for hospitalized Patients: Four Reasons explored
Authors: Willems Sara , Saelens Dirk , Heylighen Ann
Published: December 2023

Hospitalized patients’ healing process is affected by their room’s indoor environmental comfort. Models are developed to predict (dis)comfort. However, discrepancies with experienced (dis)comfort occur. Four reasons have been identified for these discrepancies: (a) people adapt, (b) in their experiences, indoor environmental quality (IEQ) factors interact, and experienced (dis)comfort and adaptation differ (c) between people and (d) between settings. To better understand these reasons and their relationships, it was investigated how hospitalized patients’ experiences of their indoor environment relate to measurable values of IEQ parameters. A multiple mixed methods case study was conducted at Belgian hospital wards. Data collection included interviews, self-documentation by patients, questionnaires, sensor measurements of IEQ parameters, and simulations of indoor conditions. Data were analysed in separate and integrated ways. (a) Five adaptation strategies were identified. They seem to impact experienced comfort psychologically in different ways. (b) IEQ factors interact in experiences because their assessment is influenced by the overall comfort. Adaptation strategies enable achieving the highest conceived overall comfort. (c and d) What one considers as comfortable and the adaptation strategies one applies to achieve it differ between participants and between settings. This better understanding is an important step towards improving comfort predictions, and therefore reducing discrepancies.
Thermal characterization of a novel heated glass element
Authors: Rovers T J H , Van ‘t Ende J A N , Gieling C W J , Struck C , Ribberink M
Published: December 2023

Although the U-value of glazing has improved significantly in the last decades, the thermal transmittance of windows remains relatively high compared to opaque elements of the thermal shell. Consequently, glazing has a relatively low interior surface temperature in the heating season, which can cause thermal discomfort. A novel heated glass element has been developed, allowing for the control of its interior surface temperature. In-situ measurements were conducted on a heated glass element, with the objective to (i) characterize its thermal behaviour, (ii) assess its thermal performance and (iii) to assess its impact on thermal comfort. The examination of heating-up and cooling-down curves of the heated glass element revealed that cooling-down is a slower process (τ2of 100 – 145 minutes) than heating-up (τ2of 70-85 minutes). In terms of thermal performance, it is shown that most of the heat provided by the heated glass element is effectively directed towards the room, rather than lost to the outdoor environment. The efficiency depends on the temperature difference between interior glass surface and the room, with efficiencies of 58 – 65% reached at surface temperatures of 23 - 25 °C, and efficiencies of 90% reached at surface temperatures of 39 – 43 °C. Comparative measurements of thermal comfort in a room with the heated glazing, and in a room with conventional triple glazing show an improvement in operative temperature.
Parametric Thermal Simulations of an Airflow-Screen Façade System
Authors: Ohga H , Kimoto K
Published: December 2023

Energy-saving performance is required for building façades, and high-performance window systems, such as double-skin and airflow windows, are being considered as viable alternatives. However, those systems are costly owing to the increased number of glazing panes. Therefore, an airflow-screen façade system (AFS) that combines glazing, a blind, and a roller shade can be a viable solution. The design issues of AFS are the backflow to the indoor side and the effect of natural convection on indoor airflow when exhaust fans are not in use during holidays and at nighttime. However, only few studies exist on the annual thermal behavior of AFS. In this study, based on the thermal load calculation program NewHASP, a simulation model of AFS was built using a thermal node solar heat gain model and a ventilation network model. Sensitivity analysis of the maximum and annual thermal load were performed with the following parameters of the AFS: roller shade airtightness, glazing type, blind slat angle control system, window orientation, and exhaust fan air volume. The results of the sensitivity analysis indicate that the maximum and annual thermal loads were the most sensitive to were the direction the window faces and the airtightness of the roller shade.
Thermal performance of indoor solar shading devices using a thermal nodal model and a lighting simulation model
Authors: Kimoto K , Ohga H , Ohki C , Yoshizawa N , Nagai T
Published: December 2023

Various facade designs, such as light shelves, have been proposed to achieve zero emission buildings. However, general thermal load simulation models are unable to properly evaluate the thermal effects of spaces near windows, such as light shelves and counters, which are installed on the interior side of windows for increased daylight utilization. In this study, we propose a method to evaluate the thermal performance of indoor light shelves. The model proposed herein consists of three components: A thermal nodal model of the window area, a lighting simulation model, and a thermal simulation model. The thermal nodal model places a node at each device (glass, ceiling, light shelf, and floor) in the light shelf space. The heat balance equation for each node is then solved. In doing so, the total transmittance of the entire indoor-installed device space, which considers inter-reflections and the solar radiation absorptance of each device, is calculated using the Radiance software. Additionally, the solar heat gain obtained using the thermal nodal model is substituted internally into NewHASP, and the thermal load calculation is performed. Finally, a simulation is performed using an office model, and the indoor-installed light shelf exhibited a 14 % reduction in annual thermal load.
Influence of window recess on solar loads, heat loss and external condensation
Authors: Wittchen Kim B. , Rose Jørgen , Nielsen Anker
Published: December 2023

The current architectural preference for the recess of windows is in line with the forefront of the building facade. The recess of a window has consequences for: solar loads, heat loss, and risk of outside condensation. This paper presents an analysis of these issues in relation to variations in recess depth and differences in orientation of the window. The solar load in buildings is highly influenced by the depth of the window recess, depending on the orientation. Solar gains both contribute to heating the building during the heating season, but also to overheating in other periods. The latter being especially important for other buildings than residential buildings. This is analysed for different window orientations and size (height and width) as wells as the recess depth. Recess depth also influences the overall heat loss though the facade and window and is analysed through detailed calculations. Last, but not least, condensation on the external face of modern low energy windows causes a serious issue regarding visual comfort in the mornings during periods with clear weather and low outdoor temperatures. Analyses of the recess depth influence on the outside condensation risk is presented. The issues regarding the recess depth for facade windows is analysed using dynamic simulations of different window and recess depths in different orientations in combination with 2D static calculations of the overall heat loss coefficient for the total window and facade construction in typical highly insulated facade constructions.
Microclimate modelling and hygrothermal investigation of freeze-thaw degradation under future climate scenarios
Authors: Mandinec Jan , Johansson Pär
Published: December 2023

Future climate scenarios lead to changes in the boundary conditions impacting the service life of building envelopes. This may increase or decrease the risk of degradation caused by e.g., freezing and thawing on brick façades. In this study, the risk of degradation based on individual years is compared for different moisture reference year (MRY) selection methods. Furthermore, two new MRY indices, based on the Frost Decay Exposure Index (FDEI), are proposed to assess future climate scenarios. A brick façade in Gothenburg, Sweden, is used as a case study to investigate the microclimate caused by façade orientation and solar radiation on three different parts of the façade. The risk of damage is compared for climate scenarios A1B and A2 from 1961 to 2100. The microclimate of the façade is modelled to obtain boundary conditions for each part instead of using MRYs as uniform boundary conditions for the whole building. The study demonstrates a 67% difference in risk of degradation between the different parts of the façade. Furthermore, the risk of freeze-thaw degradation reduces in the future. Finally, it is indicated that the basic FDEI index is better at evaluating the severity of exposure compared to its derivatives.
Impact of Tree Leaf Area Density on Cooling and Ventilation of an Urban Neighborhood
Authors: Kubilay A , Strebel D , Derome D , Carmeliet J
Published: December 2023

The impact of trees during heat waves can be diverse, as their interaction with their surroundings depends on several parameters that modify shading, ventilation potential and transpiration rate. A multiscale coupled model is presented that allows the detailed analysis of the local impact of vegetation as a mitigation measure for urban heat islands. A case study is performed on an urban neighborhood in Zurich, Switzerland, with an aim to improve the understanding of physical processes in urban microclimate subjected to a heat wave. A parametric study presents the impact of varying the leaf area density (LAD) of the existing trees in the neighborhood. Comparisons of surface temperatures and rate of transpiration with available measured data show a good agreement. The results show that urban trees can reduce heat storage during the day due to shadowing, especially when they are in groups. The reduction in air temperature due to transpiration largely depends on LAD, wind-flow patterns and urban morphology. The results also indicate locations with an increase in air temperature due to the presence of trees.
DC line fault discrimination based on maximum information coefficient
Authors: Yu Jiang , Dou Zhenlan , Chen Wei , Sun Pei , Chen Haotian , Duan Yahui
Published: December 2023

In DC networks, conventional line differential protection has the disadvantages of low reliability, weak resistance to transition resistance, and vulnerable to harmonic interference. In this paper, a fault identification method based on maximal information coefficient (MIC) is proposed for non-high resistance faults in the DC side of a flexible DC distribution network containing a modular multilevel converter (MMC) with single pole grounding DC protection inside and outside segments. The failure prediction is performed based on the reciprocal information at two sides of the line current. At the same time, for single-pole grounded high-resistance faults, the MIC is compared using the zero moduli of the current at two sides of the line for the recognition of high-resistance faults. The MMC-based flexible DC transmission network model is built and validated in the PSCAD/EMTDC platform. The results show that the method can identify faults protection inside and outside segments on the DC line area quickly and reliably. It also has the ability to resist harmonic interference and has an endurance of resistance for single-pole faults on the DC side; meanwhile, for high-resistance faults, it can also be detected accurately.
Research and Implementation of a High-efficiency and Intelligent Power Supply System for Radio Equipment
Authors: Wang Xiaoshuang , Zhao Jing , Rao Xuejun , Qi Lihua
Published: December 2023

The use of nickel-metal hydride batteries in tactical radios will lead to problems such as heavier loads, shorter battery life, and less intelligent power supply systems. Because analyzing the power supply guarantee requirements of tactical radio stations, this paper firstly models and simulates lithium-ion batteries to accurately estimate key design parameters such as lithium-ion power and balance control. Then, high-efficiency integration technologies of new materials such as PAA and LiPF6 are used to develop lithium-ion batteries with high specific energy density, good high and low-temperature performance, and lightweight. At the same time, DSP technology is used to develop battery fast charging and intelligent management software and hardware systems to achieve fast and real-time detection of battery state of charge, health state, and functional state. The battery-intelligent power supply system will provide theoretical guidance and technical support for the overall improvement of the combat effectiveness of tactical radio equipment.
Adaptability Analysis of Distribution Network Protection Technology Considering Distributed Photovoltaic Power Generation Access
Authors: Liu Jinjie , Song Xiaohui , Gao Fei , Li Yajie , Wu Yan
Published: December 2023

The integration of distributed power sources into the distribution network has transformed the traditional radial topology structure of the distribution network into a multi-source structure, which can lead to a series of problems, such as voltage violations and bidirectional power flow in the lines. This situation presents a significant challenge to traditional distribution network protection technology. Therefore, based on the electrical characteristics of random loads and distributed power sources, the impact of distributed power source integration on fault characteristics and protection is analyzed, and the adaptability of different distribution network protection methods to distributed power source integration is evaluated. Key factors for improving the protection action characteristics of the distribution network are proposed.
High-precise Motion Control Hardware System and Key Timing Management Research
Authors: Yan Honglei , Lu Hailiang
Published: December 2023

High-precise and multi-axes motion control system is required in the application of semiconductor equipment and high-performance industrial equipment. To achieve the tight performance requirements, this paper presents the control system architecture, communication, and timing management solution. We use multiple cores DSP and FPGA as the main control chips, use SRIO @5Gbps *4 as the DSP and FPGA communication protocol, and use Aurora 8B/10B @5Gpbs as the inter-board communication protocol. This architecture with its high sampling rate and low latency can improve the motion control performance and raise the system sampling bandwidth. Analysis and test results of system communication and timing management are included to demonstrate the efficacy of the proposed scheme.
Time of Flight Measurement Method Combining Threshold Method and Cross-Correlation Method
Authors: Zhu Mingrui , Zhou Hongliang
Published: December 2023

With various benefits such as a large range ratio, suitability for large-diameter measurement, and lack of excess pressure drop, ultrasonic flowmeters (UFMs) have been widely adopted in natural gas measurement. The accuracy of flow measurement in transit-time UFMs is mostly dependent on the accurate measurement of time of flight (TOF). The threshold method, the cross-correlation (CC) method, and the model-based method are examples of traditional TOF calculation techniques. However, the threshold method is susceptible to such factors as waveform distortion, amplitude attenuation, and noise, the CC method is constrained by the sampling frequency, and the model-based method necessitates a significant investment in calculation time and resources. Based on the analysis of the shortcomings of traditional TOF measurement methods, a TOF measurement method that combines the threshold method and CC method is presented. This method integrates the advantages of the high measurement resolution of the threshold method and the strong robustness of the CC algorithm. The results demonstrate that the flow rate accuracy and the repeatability of the TOF are greatly improved by this method.
Statistical Analysis of Step Stress Acceleration Test Data
Authors: Yan Kejian , Feng Anping , Yang Man
Published: December 2023

The step stress accelerated life test is the selection of a set of accelerated stress levels that are higher than normal stress levels. At the beginning of the test, a certain number of samples are placed under a certain stress level for life testing. After some time, the stress level is increased, and this continues until a certain number of samples fail. In this paper, the acceleration coefficient is used to convert the failure data under each acceleration stress level into life data. The life distribution is exponential distribution, Weibull distribution, and logarithmic normal distribution. Under a certain number of samples, the statistical analysis of step stress accelerated life test data is completed, and the estimation of each reliability index is calculated.
Design of Fuzzy Controller for Lithium Battery Formation LLC Converter Based on Sparrow Search Algorithm Optimization
Authors: Li Hongyan , Li Yongming , Xie Zhen
Published: December 2023

This paper provides a novel fuzzy PI controller design for LLC resonant converters that make use of the sparrow search algorithm optimization. The LLC resonant converter is a complex nonlinear and time-varying system. As the trend in lithium battery energy conversion systems shifts toward high-power applications, they frequently encounter wide load variations. When employing traditional linear PI controllers of LLC resonant converters, the transient response is slow and fails to adapt effectively to the requirements of wide load changes. In this proposed approach, fuzzy control and PI control are combined to enhance the controller’s flexibility and transient response characteristics. The PI controller parameters are continuously adjusted online, incorporating fuzzy control outputs to improve the controller’s performance. Furthermore, the sparrow search algorithm is applied to optimize the proportional and quantization factors, minimizing the impact of improper parameter selection on the performance of the fuzzy PI controller. This method successfully addresses the challenges posed by the LLC resonant converter, improving adaptability and transient response characteristics in varying load conditions by combining fuzzy control and PI control, online parameter modification, and utilizing the sparrow search algorithm to optimize proportional and quantization factors.
The Effect of 330 kV Porcelain Insulators Deterioration on Distributed Voltage
Authors: Xu Hejie , Wang Sihua
Published: December 2023

As a commonly used insulator type for 330 kV transmission lines, porcelain insulators are susceptible to damage by external forces during operation, resulting in deterioration. The study on the change of the distributed voltage of porcelain insulators in different deterioration states is important for the timely and accurate detection of deteriorated insulators and the maintenance of safe operation of the power grid. This paper establishes a finite element model of a 330 kV AC transmission line. By changing the resistance values of single insulators at different positions in the insulator strings, the distributed voltage variation law of insulators under different deterioration states is simulated. Analysis of the results shows that the voltage drop is higher in the presence of two consecutive degraded insulators than in the case of a single degraded insulator with the same degree of deterioration. The existing criterion of “less than 50% of the standard value of the distributed voltage” for determining insulator degradation is likely to cause misjudgment in the case of high insulation resistance of low-value insulators and needs to be improved.
Control strategy for three-phase four-switch active power filter based on positive sequence extraction in stationary coordinate fundamental reference frame
Authors: Guo Fengfeng , Qiao Jiping , Jia Tianyu , Wang Lei
Published: December 2023

Traditional three-phase four-switch active power filter often uses the method of phase-locked loop (PLL) and low-pass filter for harmonic detection, which seriously affects the detection accuracy. In order to improve the detection accuracy, a lock-free three-phase four-switch active power filter based on fundamental positive sequence extraction is proposed. The harmonic detection adopts the fundamental positive sequence extraction method, and the rotation coordinate axis transformation adopts the phase-locked loop (PLL) free method. Compared with the traditional three-phase four-switch active power filter, this method does not require a phase-locked loop and a low-pass filter, and does not need complex coordinate transformation[2].The control method is simpler. Finally, simulation results prove the effectiveness of the control method.
State of energy estimation of lithium battery based on least squares and support vector regression
Authors: Yao Bowei , Liu Gaoling , Liu Baolei , Zhai Kejiao , Wei Jinyi , Yin Xilin
Published: December 2023

To enhance the estimation precision of lithium battery state of energy (SOE) and avoid the complex modeling and parameter identification process in the estimation process, a joint algorithm using the least square method (LS) and support vector regression (SVR) is proposed in this paper. Data on the voltage, current, temperature, and charge state of the lithium battery are extracted and incorporated into the energy factor. The lithium battery SOE estimation model is designed by the least-squares support vector regression (LS-SVR) methods, while the grid optimization method is deployed to optimize the hyper-parameters. Finally, the SOE prediction of lithium batteries under a dynamic scenario is realized. Comparison results show that the energy factor chosen in our article accurately reflects the SOE of lithium batteries, and the MAE is within 1.5%.
An online diagnosis method for the inter-turn fault of current transformer based on ΔI-E curves
Authors: Zhou Shaoping , Wei Pingan , Li Xiang , Jiang Lan
Published: December 2023

The inter-turn short fault of the secondary coil is the most frequent fault for current transformers. Failure to detect this fault promptly will affect the accuracy of electrical measurement and the correctness of relay protection actions. This paper proposes an online diagnosis method for inter-turn short faults in current transformers. A ΔI-E curve is constructed based on the real signal of the primary winding and the measurement signal of the secondary winding. The working condition of the current transformer is reflected by the change in the curve. Simulation results show that the proposed method can detect the inter-turn short fault of the current transformer online and sensitively, which has certain practical value.
The outflow characteristics of PV water lifting systems based on multiple tracking strategies
Authors: Hu Wei , Hou Shiwen , Zhu Junfeng , Li Liang , Cao Liang , Hao Weigang
Published: December 2023

In order to clarify the problems of high failure rate, low efficiency, and low outflow rate of PV water pumping stations in pastoral areas due to large differences in resource conditions and poor equipment matching, this study uses the PV water supply model, establishes a pilot site for PV human storage water supply in pastoral areas, carries out research on the relationship between solar energy resources, water supply demand and power system of PV water pumping stations based on group observation tests in the field, and analyzes the PV system. We analyzed the relationship between different tracking operation modes and the amount of solar radiation and water supply flow, and compared the outflow characteristics of fixed type, single-axis tracking type, and double-tracking axis type, in order to explore a kind of PV water pumping station technology suitable for human storage and drinking water in pastoral areas, which can meet the water demand of pastoral water users. The research results show that the single-axis and dual-axis water lifting systems are significantly more efficient than the fixed-support water lifting system, receiving solar radiation at more than 80% of the maximum radiation throughout the day, and lifting water flow at more than 90% of the maximum discharge flow. Compared with the fixed-support PV water lifting system, the radiation of the single-axis PV water lifting system increases by 28.9%, and the daily water output increases by 43%; for the dual-axis PV water lifting system, compared with the single-axis PV water lifting system, the daily radiation of the dual-axis PV water lifting system increased by 4.8% and the daily water output increased by 3.2%; the starting radiation of the PV water lifting system was 256 W/m2.
A Coordinated Reclosing Strategy for Maintained Transformer in Offshore Wind Power Systems
Authors: Chen Jixu , Wei Qing , Li Yanna , Zhou Sunpeng , Zhang Ping , Wang Dong
Published: December 2023

Offshore wind power generation system needs to consider the maintained transformers to reclose. The close loop operation can meet the requirement for reclosing the maintained transformer and maximize the use of wind resources without disconnecting wind turbines. However, close loop operation will cause system damping which can easily cause system instability and protection maloperations. To suppress close loop current damping, a flexible reclosing strategy is proposed that coordinates control of the main bus switch and transformer-connected flexible switch which consists of a damping buffer branch and pass branch. The coordinated control of switches realizes the optimized reclosing state of the maintained transformer. Finally, case studies are established in PLECS simulation software to evaluate the effectiveness of the proposed flexible reclosing strategy to eliminate the reclose damping oscillation for maintained transformers in offshore wind power generation systems.
Optimal Configuration of Voltage Sag Monitoring Points Considering Branch Current based on War Strategy Optimization Algorithm
Authors: Shou Shaoan , Luo Hairong , Zhang Renhe , Ji Tao , Liu Quan , Su Liqian
Published: December 2023

In recent years, a large number of distributed power sources have been connected to the power grid, and the power quality problem has been deteriorating. In order to comprehensively evaluate the voltage information and current information and realize the guidance of power quality monitoring, this paper considers the global monitoring of fault points and obtains branch current information as much as possible. The concept of average redundancy is added to establish the optimal configuration model of voltage sag monitor. The model is solved by the war strategy optimization algorithm, and the optimal configuration simulation of IEEE39 nodes is carried out by MATLAB. The optimal configuration scheme of the monitor is obtained, and the feasibility and effectiveness of the scheme are verified.
Capacity Prediction of VRLA Batteries Based on Stepwise Regression Analysis
Authors: Le Xubo , Wang Xueyan , Li Haibo , Zhang Bingye , Zhao Xing , Zou Xiyong
Published: December 2023

Effective maintenance of valve-regulated lead-acid (VRLA) battery groups within substations is critical for DC system reliability. Therefore, assessing battery health and remaining capacity is essential. In this study, we focus on predicting the VRLA battery group remaining capacity and propose a prediction model based on stepwise regression. This model utilizes operational data, combining the charging and discharging characteristics of VRLA batteries. Stepwise regression selects the optimal independent variable subset, mitigating poor predictions from using all variables in multiple linear regression. Experimental results validate the accurate prediction of lead-acid battery capacity decline, offering effective forecasts. This model is expected to be widely applied in the capacity prediction of DC power systems in substations.