Journal of Shandong University(Engineering Science)

Review and prospect of research on new power system synchronous stability

ZHANG Hengxu, MA Ruicong, CAO Yongji, LIU Yimin, ZOU Shihao

Journal of Shandong University(Engineering Science). 2025, 55(2): 1-15. doi:10.6040/j.issn.1672-3961.0.2024.117

Abstract ( 229 )

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The stability characteristics of the new power system changed greatly. To enhance the understanding of synchronous stability problems, the review and prospect of research in relevant fields were presented. The differences in synchronous stability mechanisms between the traditional alternating current power system and the new power system were clarified, where the synchronous behavior of the grid-following converter and the grid-forming converter was analyzed. The theoretical framework for static and transient synchronous stability was discussed, and the current strategies to improve synchronous stability in the new power system were summarized. The empirical achievements in synchronous stability research were reviewed, and the critical research directions that require urgent attention were identified, serving as a reference for future in-depth studies.

Bi-level optimization strategy for active distribution networks considering carbon emission factors and dynamic reconfiguration

YAN Renwu, LIN Jianxiong, LI Peiqiang, WU Guoyao, KUANG Yu

Journal of Shandong University(Engineering Science). 2025, 55(2): 16-27. doi:10.6040/j.issn.1672-3961.0.2024.014

Abstract ( 135 )

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To improve the consumption rate of photovoltaic and promote the low-carbon and economic operation of active distribution networks, a bi-level optimization strategy for active distribution networks that considered factors of carbon emission and dynamic reconfiguration was proposed. The upper-level considered dynamic reconfiguration, energy storage devices and distributed photovoltaic multiple active management measures to reduce the system network loss cost and light abandonment cost that realized the optimal economic operation of the active distribution network. The lower-level established a low-carbon demand response model based on the theory of carbon emission flow with the dynamic carbon emission factor as the guiding signal, which can fully explore the potential of carbon reduction on the user side. According to the characteristics of this model, the second-order cone planning and improved dung beetle optimization algorithm were used to solve the converted model, respectively. The simulation of the improved IEEE 33-bus system was carried out to verify the effectiveness of the proposed strategy in reducing the risk of voltage overruns and promoting the low-carbon economy of active distribution network operation.

Coordinated optimal scheduling of electric-hydrogen system considering hybrid energy storage in the day-ahead and intra-day stages

WANG Ruiqi, LIU Jiyan, JU Wenjie, WANG Weishuai, XU Wenze, ZHANG Zhenbin

Journal of Shandong University(Engineering Science). 2025, 55(2): 28-36. doi:10.6040/j.issn.1672-3961.0.2024.044

Abstract ( 114 )

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To respond to the goal of "dual carbon" and deal with the abandonment of wind power and photovoltaic caused by the access of large-scale renewable energy, a coordinated optimal scheduling of an electric-hydrogen system(EHS)considering hybrid energy storage in the day-ahead and intra-day stages was proposed. By considering the constraints of the system and each equipment, the objective function was established to minimize the operating cost and carbon emissions of the EHS. The nonlinear constraints in the model were linearized, and the model of multi-time scale scheduling method was established. The IEEE-33 node system was used to analyze the proposed strategy and verify its effectiveness in promoting the accommodation of renewable energy and the low-carbon economic operation of the EHS. The simulation results showed that the proposed strategy could effectively improve the system's accommodation capacity of renewable energy and reduce EHS's carbon emission and operating costs.

A cooperative control strategy of integrated photovoltaic-energy storage system considering SOC security boundary

WANG Shibo, SUN Shumin, CHENG Yan, ZHOU Guangqi, GUAN Yifei, LIU Yiyuan, ZHANG Zhiqian, ZHANG Zhenbin

Journal of Shandong University(Engineering Science). 2025, 55(2): 37-44. doi:10.6040/j.issn.1672-3961.0.2023.308

Abstract ( 124 )

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To solve the problems of accelerated battery aging, poor economic performance, and slow dynamic response speed of the integrated photovoltaic-energy storage system, when the state of charge(SOC)of battery exceeded safety boundary, a cooperative control strategy for integrated photovoltaic-energy storage system considering SOC security boundary was proposed, which was based on the operation characteristics of the integrated photovoltaic-energy storage system. When the SOC reached the preset boundary, the working mode of converter was automatically switched to ensure healthy operation of system and endow the system with frequency support capability. A virtual synchronous generator(VSG)strategy based on model predictive control was designed to achieve inertia support for grid and fast response to the load power demand. By constructing a MATLAB/Simulink simulation model of integrated photovoltaic-energy storage converter system, the power-frequency response characteristics of storage batteries at SOC exceeding the boundary were compared and analyzed. The results indicated that compared to traditional dual-loop control, model predictive control provided faster dynamic adjustment performance, and SOC remained within the safety boundary. The proposed method accelerated the power response speed of the integrated photovoltaic-energy storage system, and effectively improved the active support capability to the power grid.

Intelligent building energy optimization considering user satisfaction

ZHENG Fangyuan, CHEN Lizheng, WANG Wenkui, ZHANG Hanyuan, FAN Yingle

Journal of Shandong University(Engineering Science). 2025, 55(2): 45-57. doi:10.6040/j.issn.1672-3961.0.2024.113

Abstract ( 102 )

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To improve building energy efficiency, a low-carbon intelligent building energy optimization system was constructed in this study. The energy optimization system model for intelligent building was constructed. lighting and air conditioning loads were considered as flexible loads to participate in the optimal scheduling of the system, which increased the flexibility of system scheduling. In addition, bidirectional interaction between electric vehicles and intelligent buildings was enabled, and electricity could be transmitted by intelligent buildings to the utility grid in two directions according to the time-of-use electricity price. Based on the above model, a multi-objective optimization problem composed of power generation cost and user satisfaction was constructed with the goal of minimizing operating cost and ensuring user satisfaction. The weighted sum method was used to deal with the multi-objective problem, and then the system model was optimized by CPLEX. Compared with several different strategies, the system operation cost can be reduced by the strategy proposed in this paper on the premise that the user satisfaction is ensured to be above 0.95. The comparison results of the numerical examples proved that the energy conservation and emission reduction in intelligent buildings could be achieved and the economy of the system could be improved by the intelligent building energy optimization method proposed in this study.

Density peak clustering combining local truncation distance and small clusters merging

CHEN Sugen, ZHAO Zhizhong

Journal of Shandong University(Engineering Science). 2025, 55(2): 58-70. doi:10.6040/j.issn.1672-3961.0.2024.045

Abstract ( 93 )

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Aiming at the problems that the truncation distance defined by the density peak clustering algorithm only considered the global distribution of samples and the "domino" phenomenon was easy to occur when assigning samples, a novel density peak clustering algorithm combining local truncation distance and small clusters merging was proposed. The truncation distance and local density of each sample were calculated based on the local distribution information of samples, which were conducive to accurately obtaining the density peaks on complex structure datasets. Potential density peaks were selected based on the difference between samples decision values and multiple small clusters were formed. A new kind of similarity between clusters was defined, and clusters were merged to obtain clustering results according to this similarity, which effectively avoided the "domino" phenomenon. Compared with several clustering algorithms on six synthetic datasets and eight UCI datasets, the standardized mutual information, adjusted rand index and adjusted mutual information average values of the proposed algorithm on 14 datasets were 18.15%, 28.99% and 20.22% higher than the five comparison algorithms on average, especially 30.06%, 47.15% and 31.90% higher than original density peak clustering algorithm. Experimental results showed the proposed algorithm had a good clustering effect.

Single image 3D model retrieval based on instance discrimination and feature enhancement

DIAO Zhenyu, HAN Xiaofan, ZHANG Chengyu, NIE Huijia, ZHAO Xiuyang, NIU Dongmei

Journal of Shandong University(Engineering Science). 2025, 55(2): 71-77. doi:10.6040/j.issn.1672-3961.0.2024.164

Abstract ( 116 )

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To reduce the modal gap between the image domain and the model domain in 3D model retrieval algorithms, a neural network algorithm model consisting of four modules was proposed. The data exchange module exchanged image and 3D model data with a certain probability, allowing the image domain network to learn model domain features and the model domain network to learn image domain features, thus initially reducing the modal gap. The feature alignment module included an instance sample discrimination loss function and an image-model pairing loss function, which further aligned the image domain and model domain. The instance discrimination loss function treated each instance as an independent class and classified it, making the features of the same instance's images and 3D models similar. The image-model pairing module aimed to bring closer the images and 3D models of the same instance and push apart the images and 3D models of different instances. Based on contrastive learning, a feature enhancement module was added to the image domain to improve feature discrimination within the image domain. The experimental results showed that the proposed algorithm achieved good results on three common datasets: Pix3D, CompCars, and StanfordCars, improving retrieval accuracy by up to 4.5% compared to existing classical methods. This aligned the image domain and the 3D model domain, reduced the modal gap, and improved the accuracy of image retrieval of 3D models.

A relation extraction method based on improved RoBERTa, multiple-instance learning and dual attention mechanism

WANG Yuou, YUAN Yingchun, HE Zhenxue, WANG Kejian

Journal of Shandong University(Engineering Science). 2025, 55(2): 78-87. doi:10.6040/j.issn.1672-3961.0.2024.050

Abstract ( 124 )

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Aiming at the problem that distant supervision relation extraction could not make full use of the high-level information of sentence context and was easy to bring noise annotations, a relation extraction method based on improved robustly optimized bidirectional encoder representations from Transformers pretraining approach(RoBERTa), multiple-instance learning(MI)and dual attention(DA)mechanism was proposed. The full-word dynamic mask was introduced on the RoBERTa to obtain the text context information and the word-level semantic vector. The feature vectors were input into bidirectional gated recurrent unit(BiGRU)to mine the deep semantic representation of the text. Multiple-instance learning was introduced to narrow the range of relation extraction categories by learning instance-level features. Dual attention mechanism was introduced, which combined the advantages of word-level attention mechanism and sentence-level attention mechanism to fully capture the feature information of entity words in the sentence, improved the model's attention of effective sentences, and enhanced the expression ability of sentences. The experimental results showed that the F₁ value of the method reached 88.63% and 90.13% on the public dataset New York Times(NYT)and Google IISc distant supervision(GIDS), which were better than the mainstream comparison methods. It could effectively reduce the noise influence of distant supervision, realize the relation extraction, and lay a theoretical foundation for the construction of knowledge graph.

Concept drift detection based on graph structure

ZHOU Yanbing, MA Shilun, WEN Yimin

Journal of Shandong University(Engineering Science). 2025, 55(2): 88-96. doi:10.6040/j.issn.1672-3961.0.2024.184

Abstract ( 121 )

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In order to solve the problem that the traditional concept drift detection method only relied on the error rate for drift detection was not reliable enough, a concept drift detection method based on graph structure was proposed. In this method, the k-associated optimal graph was used to represent the current data distribution, and the drift rate of the sample was defined to represent the inconsistency between the classifier and the current data distribution. The drift rate was used to form a bit stream, and the concept drift detector was used to detect the concept drift on the bit stream. Compared with the traditional concept drift detection method using error rate, the results showed that the accuracy of the base classifier was improved by 1%-5% on artificial datasets and 1%-2% on real-world datasets. The proposed method could effectively improve the accuracy of concept drift detection and help base classifiers better adapt to concept drift.

Properties of carbonized steel slag fine aggregate concrete

XUE Gang, WU Song, DONG Wei

Journal of Shandong University(Engineering Science). 2025, 55(2): 97-105. doi:10.6040/j.issn.1672-3961.0.2024.010

Abstract ( 102 )

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In order to study the applicability of the carbon steel slag fine aggregate in concrete and mechanical properties of differences, physical and chemical tests were conducted on carbonated steel slag. Based on this, ordinary concrete and fine aggregate concrete with 10%, 20% and 30% carbonized steel slag were prepared. The influence law of the replacement rate of steel carbide slag on the mechanical properties and volume stability of concrete was studied. Research had found that with the addition of fine aggregate of carbonized steel slag from 10% to 30%, the cube compressive strength, splitting tensile strength, elastic modulus, and peak strain of carbonized steel slag aggregate concrete gradually increased. Axis of normal concrete compressive strength and cube compressive strength ratio was 0.76-0.82, and that of carbonized steel slag concrete was 0.85-0.87. At the same time, the constitutive relationship models applicable to carbonated steel slag fine aggregate concrete were studied and summarized, and the relationship between model fitting parameters and mechanical properties was analyzed, In order to provide theoretical support for the application and popularization of steel slag concrete.

Frost resistance of fiber reinforced concrete based on Wiener degradation process

YIN Yingzi, WEI Jingtao, ZELI Luobu, DONG Wei

Journal of Shandong University(Engineering Science). 2025, 55(2): 106-113. doi:10.6040/j.issn.1672-3961.0.2024.022

Abstract ( 94 )

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In order to explore the impact of basalt fiber(BF)on the durability and service life of aeolian sand concrete(ASC), this experiment used aeolian sand to replaced river sand, and the mass of aeolian sand accounts for 20% of the mass of river sand in the concrete after replacement, and the basalt fiber aeolian sand concrete(BF-ASC)was prepared under the conditions of 0, 0.05%, 0.10%, 0.15%, and 0.20% BF content. The effects of different BF content on concrete mass and relative dynamic elastic modulus were studied, and the damage and deterioration mechanisms of BF-ASC was analyzed by scanning electron microscopy(SEM). With the relative dynamic elastic modulus of BF-ASC test block as the degradation index, a single Wiener function was used to model the degradation process and predict the life of BF-ASC. The results showed that adding BF could reduce the porosity of ASC, enhance the bonding strength between coarse and fine aggregates, significantly improve the frost resistance of concrete, and reduce the freeze-thaw damage degree of concrete. When the volume fraction of BF was 0.20%, the mass loss rate was the lowest, the relative dynamic elastic modulus evaluation parameter had the smallest decrease, and the frost resistance effect was the best; The reliability function of BF-ASC obtained based on Wiener random distribution with BF-ASC relative dynamic elastic modulus as the degradation index could effectively predict the service life of BF-ASC in salt freezing environment, and the longest service life could reach about 2 500 hours when the BF volume fraction was 0.20%.

Research on pebble slagging stagnation of slurry balance shield drain pipe based on CFD-DEM coupling

TONG Li, LI Da, LI Shuchen, PENG Kefeng, CHEN Yi

Journal of Shandong University(Engineering Science). 2025, 55(2): 114-124. doi:10.6040/j.issn.1672-3961.0.2024.040

Abstract ( 100 )

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Three-dimensional modeling was carried out for the curved pipeline of slurry balance shield, and numerical simulation was carried out using CFD-DEM coupling to reveal the migration law of pebbles carried by slurry, analyze the causes of the slagging stagnation of pebbles, explore the influence of pebble deposition on the flow field in the pipeline, and provide optimization guidance for the solution of the delayed drainage problem in field construction. The results showed that the problem of slagging stagnation was due to the low drag force provided by the low flow rate slurry, and a large number of particles were deposited at the bend of the pipeline. The larger the curved pipe was, the later the critical pointed at which the particle formation velocity and slagging velocity reached the dynamic equilibrium, indicating that the more the number of deposit particles. Particle deposition made the effective flow area smaller, the slurry flow rate was obviously stratified, and the stratification of flow field was more unfavorable to the migration of sediment particles at the bottom, which aggravated the problem of hysteresis. The larger the viscosity of the slurry, the greater the drag force of the particles between slurry, and the larger the average migration velocity of the particles. Slurry density had little effect on the horizontal movement of particles, but when particles were transported upward, slurry density could provide higher buoyancy, which was conducive to preventing the stagnation of particles.

Evaluation of containment properties and optimization design of water curtain system for an extended underground oil storage cavern

PENG Zhenhua, WANG Zhechao, LI Jiajia, QIAO Liping, ZHAO Qinni, LI Hanshuo

Journal of Shandong University(Engineering Science). 2025, 55(2): 125-133. doi:10.6040/j.issn.1672-3961.0.2024.190

Abstract ( 111 )

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The expansion of underground water-sealed oil depot may have mutual influenced on the built adjacent caves. In view of the first large-scale groundwater sealing reservoir expansion project in China, this research carried out the analysis of the water-sealed efficiency of the expansion and the analysis of the mutual influence between the expansion project and the water sealing performance of the existing project. The water curtain system of the expansion project was optimized according to the groundwater level and water sealing efficiency. The results showed that the excavation of the expansion cave project had disrupted the initial stable seepage field underground, leading to a slight decrease in the water level of the existing cavern and an increase in water inflow, but the water-sealed of the built cavern still meeting the requirements. The research results indicated that the construction of expansion projects had limited impact on the water tightness of existing projects; Compared to building a separate site for the construction of a reservoir, expanding next to an existing cavern resulted in a decrease in groundwater level and water inflow, but the decrease was not significant and met the water seal requirements. In conclusion, it was feasible to expand next to existing projects. In accordance with the requirements of the groundwater level, the optimization of the water curtain system for expanding the underground water sealed cavern could be carried out by appropriately reducing the pressure of the water curtain holes and increasing the spacing between the water curtain holes.

The prevention and control of seawater intrusion into underground water-sealed oil storage cavern on an island

WANG Jingkui, QIAO Liping, WANG Fei, WANG Zhechao, LI Wei

Journal of Shandong University(Engineering Science). 2025, 55(2): 134-142. doi:10.6040/j.issn.1672-3961.0.2024.033

Abstract ( 91 )

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In order to prevent seawater intrusion caused by large-scale underground excavation on the island, which affected the construction and operation safety of the underground water-sealed oil storage cavern, a research on the prevention and control of seawater intrusion had been carried out on the basis of the underground water-sealed oil storage cavern project on a certain island. Through the finite element numerical simulation method, the seepage field and seawater intrusion control effect of underground water-sealed oil storage cavern under the working conditions of different horizontal water curtain design parameters during the construction period of cavern excavation without water curtain and after 50 years of operation period were obtained. The study showed that: cavern excavation without water curtain does not meet the water-sealed property, additional water curtain system was required; the groundwater level was elevated after oil storage in the cavern compared to the cavern vacancy, and the water inflow and seawater intrusion were reduced; the installation of horizontal water curtains only during the operation period could not completely prevent the entry of seawater, but could only control it to a certain extent; the effectiveness of water-sealed property, water inflow and seawater intrusion control was positively correlated with the length of water curtain holes and water injection pressure, and the water injection pressure had a higher degree of influence.

Study on the strength of single fracture rock mass affected by temperature differences under tensile-shear stress

ZHANG Yan, LAI Qianlong, REN Xiang

Journal of Shandong University(Engineering Science). 2025, 55(2): 143-155. doi:10.6040/j.issn.1672-3961.0.2024.060

Abstract ( 80 )

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In order to study the effect of temperature difference on the mechanical properties of fractured rock mass under tensile-shear stress, the expression of fracture strength of single fractured rock mass under temperature difference was derived based on energy and linear elastic fracture mechanics theory from the phenomenon of rock mass tensile-shear failure in high rock temperature tunnels and slopes. The strength of fractured rock and the mechanism of crack growth and evolution under tensile and shear stress were systematically studied by combining the factors of fracture inclination, horizontal pressure and temperature stress with numerical method. The results showed that under tensile-shear stress conditions, as the temperature difference increasing from 5 ℃ to 15 ℃, the rock thermal expansion occured and the internal stress of fractured rock mass increased. When the fracture inclination angle was from 155° to the direction of the maximum shear stress of 180°, the main shear stress was easier to act on the fracture surface, which reduced the resistance to shear and the initial crack strength, thus promoted the fracture shear and spreaded. This study revealed the strength characteristics of single fissure rock mass under the condition of temperature difference influenced by many factors, which was helpful for engineers to make preliminary assessment of the stability of rock mass in the design stage, so as to formulate corresponding construction plans and preventive measures.

The stable motion response of floating platform based on swing arm float array

DONG Ge, HUANG Shuting, WANG Jun, XUE Gang, LIU Yanjun

Journal of Shandong University(Engineering Science). 2025, 55(2): 156-164. doi:10.6040/j.issn.1672-3961.0.2023.284

Abstract ( 112 )

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In order to solve the problem of safety and working performance of floating platform in complex environment sea area, the measures to improve the stability of floating platform were put forward. The swing arm float wave energy conversion device was mounted on the floating platform, a multi-body coupled hydrodynamic model of the swing arm float array and the floating platform was established, and the AQWA hydrodynamic simulation software was used to carry out numerical simulation and parametric analysis to reveal the interaction mechanism between the swing arm float array and the stability of the floating platform, and the effect of the shape and number of swing arm floats and the wave period on the stability of the floating platform were obtained, and the optimal swing arm float carrying method was found. The results showed that the floating platform equipped with swing arm float could better reduce the sloshing amplitude, and the hemispherical swing arm float could significantly reduce the pitch amplitude of the platform compared with cylindrical and conical swing arm floats. The increase of the number of swingarm float arrays would gradually reduce the shaking amplitude of the platform. In the case of a given wave height and changing the period, the floating platform equipped with swing arm floats could significantly reduce the shaking amplitude, but with the increase of the number of swing arm floats, the improvement of platform stability was less obvious. Therefore, if only the stability of the platform was considered, a small number of swing arm floats could be equipped to reduce costs, and if the wave energy device was considered to supply power to the platform, a large number of swing arm floats could be equipped to improve energy supply.

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