bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrazine monohydrate modifying Ti3C2Tx in alkaline electrolytes for high-performance capacitive properties
Authors: Yang Jiaxin , Cui Weibin
Published: September 2023

MXene has shown a bright future in the electrochemical field, benefiting from its excellent conductivity and surface hydrophilicity. However, the performance of MXene in the field of supercapacitors is seriously impaired by restacking and a large number of F-containing functional groups, especially in alkaline electrolytes. Herein, hydrazine monohydrate is used to intercalate Ti3C2Tx, and the surface chemistry of MXene is effectively optimized. In 2 M KOH, the specific capacitance of Ti3C2-HM after modification is 157 F/g, which is 35% higher than the original one.
Numerical Simulation of Heat Transfer Characteristics of Finned Tube Heat Exchanger at Different Flow Velocities
Authors: Mei Chao , Li Ying , Yao Wenzhuo , Chen Mengdong , Kang Wei , Deng Zhanfeng
Published: September 2023

A heat exchanger is an important component where high-temperature hot air and normal-temperature water exchange heat. The heat exchange area of the finned tube heat exchanger is calculated by the rated working conditions. However, with the decrease of the heat storage temperature, the hot air temperature at the outlet of the thermodynamic energy storage device changes in a large range, directly affecting the heat exchange capacity and efficiency of the finned tube heat exchanger. This paper’s three-dimensional model is established. The heat exchanger of the finned tube is designed according to the temperature of the outlet section and the return section temperature of the heat storage system. The thermodynamic physical parameter property and characteristics of which heat exchanger’s finned tube in the air’s velocity range of 1∼10 m/s are simulated by fluent software. The velocity, temperature, pressure, and heat exchanger coefficient distribution characteristics at different positions along the airflow direction are obtained. The simulation results show that the mean flow velocity is 2.0 m/s and 5.0 m/s at the inlet cross-section. The average temperature difference between the inlet and outlet is 69.5 K and 100.5 K, respectively. The fin surface temperature difference between the first and eighth rows of finned tubes is 12.5 K and 14.4 K, respectively. The air pressure loss at the air channel inlet’s section and outlet’s section is 16.1 Pa and 69.4 Pa, respectively. When the inlet flow rate change from starting at 1.0 m/s and ending at 10.0 m/s, the tube’s wall coefficient of heat transfer, which is the second level of finned tubes, only increases by 1.8 times. The tube’s wall coefficient of heat transfer of the eighth level of finned tubes increases by the maximum, to 5 times the original, but the heat energy exchange capacity of which the second level of finned tubes is always the strongest.
Investigation of Heat Storage Coupled with Night Ventilation for Office Buildings in Summer in Cold Regions of China
Authors: Yin Chengtai , Xiu Pengyue , Ding Shuaijie , Zhang Guanmin
Published: September 2023

Building operational energy consumption, which constitutes a significant portion of China’s total social energy consumption, is a top priority in current research on energy-saving buildings. Thermal mass can be utilized to store heat energy in buildings, resulting in energy flexibility on the demand side. Numerical simulations in this paper study the whole heat transfer process of building thermal mass and the distribution of indoor air temperature and thermal mass temperature under different ventilation conditions in Jinan, a typical city in cold regions of China. By implementing a night ventilation scheme, buildings with high thermal storage capacity can store substantial amounts of cooling energy, resulting in a lower indoor temperature on the following day, and thereby improving overall indoor comfort. During the day, the wall surface temperature drops to less than 302 K, and the indoor temperature decreases by 2∼4 K, while the wall absorbs 1535 kJ of indoor heat. The rule of heat storage and release of heat mass is studied in this paper, and the feasibility of energy use flexibility on the demand side is demonstrated.
Evaluation of Renewable Energy Hosting Capacity of Grid with Multi-Infeed HVDC
Authors: Jiang Shiyao , Yu Haifeng , Xie Jiarui , Qi Junfeng , Tang Fei
Published: September 2023

Considering the impact of large-scale renewable energy access to a multi-infeed HVDC receiving-end system on its voltage stability and multi-infeed short circuit ratio, a renewable energy acceptance evaluation method based on an improved holomorphic embedding method is proposed. Firstly, to construct a model containing only an AC system, the DC inverter is simplified into an AC source model; secondly, the sigma index is used to judge the static voltage stability of the system bus and determine the access location of renewable energy, and sensitivity index is used to determine the scheme of replacing conventional units with renewable energy; then, with the voltage crossing the set range as the constraint condition, the analytical expression of each bus voltage obtained by the holomorphic embedding method is used to solve the maximum renewable energy capacity of the system; finally, under the maximum hosting scenario of renewable energy, verify the multi-infeed short circuit ratio at each DC drop point. The effectiveness of the proposed method is verified on an improved IEEE39-bus system.
Analysis of Migration Characteristics of Supercritical CO2 and Mechanism of Oil and Gas Production in Condensate Gas Reservoirs
Authors: Sun Boyu , Zhang Guofang , Wang Fuping , Hu Xu , Wang Xiulian
Published: September 2023

At present, circulating gas injection is the most effective development method for condensate gas reservoirs in China, but the phenomenon of dry gas overlap has seriously affected the development effect of circulating gas injection in condensate gas reservoirs, while CO2 injection is used to drive gas, which can make CO2 widely used in removing retrograde condensation of condensate gas reservoirs, improving the development effect of gas reservoirs. This paper by comparing the migration laws of injected dry gas and injected CO2 obtains that the dry gas with a smaller density flows to the upper space of the reservoir, while the CO2 with a larger density settles to the lower part. With the injection of CO2 into the reservoir, the content of CO2 in the crude oil increases, the volume of condensate oil expands significantly, and the flow capacity of condensate oil in the formation is improved. Injecting CO2 into the formation can reduce the viscosity of condensate. The mixture of CO2 injected into the formation and formation water is slightly acidic, which can dissolve some cement in the rock. With the increase of CO2 injection, the interfacial tension between oil and water will also increase, which is unfavorable for the stability of the oil-water system and is easy to emulsify. After demulsification, the viscosity will decrease and the condensate oil will flow more easily. The dissolved carbon dioxide in the water is in a weak acid state, which is easy to corrode and shed particles, improving the reservoir space and seepage conditions near the well. It will provide theoretical support for the effective development of a condensate gas reservoir.
Fabrication of flexible nitrogen and phosphorus-codoped porous carbon membrane and investigation of capacitance performance
Authors: Li Xiao , Zhou Bin , Qin Biao , Lan Yujin , Li Yihong , Zhao Shiyong , Cai Jiangtao
Published: September 2023

Porous carbon materials have been used extensively in new energy storage materials. They have the advantages of high stability, large specific surface area, and good electrical conductivity. However, carbon material capacitance still needs to be increased. In this paper, nitrogen and phosphorus-codoped porous carbon membrane (NPCM) was prepared by electrostatic spinning using polyacrylonitrile (PAN) as a carbon and nitrogen source, triphenylphosphine (TPP) as a phosphorus source and SBA-15 as a templating agent. When PAN/TPP was set to 2:1, the resulting NPCM has good flexibility, with N and P doping content of 13.8% and 0.5%, respectively, and a specific surface area of 872 m2/g. The NPCM was used as the working electrode with 1.0 M H2SO4 electrolyte and a specific capacitance of 215 F/g was achieved at a current density of 0.5 A/g by a three-electrode test, The capacitance retention rate could reach 103% after 1000 charge/discharge cycles at a current density of 2.0 A/g. Therefore, these results indicate that NPCM has great potential for application in high-performance flexible supercapacitors.
Adaptive identification method of new energy grid operation risk based on linear decision function
Authors: Xiong Xiaocui , Chen Songling , Fang Xiaoming , Zhang Mingnian , Zhang Xiaoming
Published: September 2023

The current conventional risk identification method of new energy grid operation mainly achieves risk identification by mining equipment status information, which leads to poor identification effect due to the lack of effective extraction of abnormal data features. In this regard, a linear decision function-based adaptive risk identification method for new energy grid operation is proposed. The data flow model is constructed by combining the linear decision function, and the features of interval abnormal data and fluctuating abnormal data are extracted. A sliding window model is constructed, and the unsupervised model is used to realize the effective update of new energy grid operation data. In the experiments, the proposed method is verified for recognition accuracy. The experimental results show that when the proposed method is used to identify the risk of grid operation, the effective data mis-deletion rate of the algorithm is low and has a more desirable identification effect.
Assessment Technology and Application of Wind Energy Resources in Complex Mountain Areas at High Altitude
Authors: Yang Pengcheng , Dai Liwei , Zhang Jun
Published: September 2023

Based on the meteorological stations and wind measurement data of a high-altitude region in Liangshan Prefecture, Sichuan Province, collation, analysis, and evaluation are carried out. The results show that: the prevailing wind direction in the region is stable and the wind energy resources have a certain development value, but the turbulence intensity is high and belongs to IEC Class B, which has a certain impact on the fatigue load of wind turbines, and the safety of local wind turbines needs to be reviewed.
Optimization Configuration of Distributed Multi-Energy Complementary Energy Systems
Authors: Wang Yang , Zhang Sheng , Yao Guangyuan , Wang Jingnan , Wu Jian , Lu Shian , Cheng Yunguo , Wang Qianggang , Dai Xuhui
Published: September 2023

This paper points out the uncertainty of existing optimization models due to factors such as environmental and equipment output, which have a significant impact on the accuracy and rationality of system planning. Therefore, this paper establishes a full-working-condition-mathematical model for distributed multi-energy complementary energy systems and constructs an optimization configuration mathematical model with the total annual cost of the system as the optimization objective. Subsequently, an energy supply equipment optimization configuration method for distributed multi-energy complementary energy systems is proposed. Finally, the effectiveness of the proposed optimization configuration method is verified through case studies. This research will have important guiding significance for the construction and operation of distributed multi-energy complementary energy systems.
Heating performance enhancement in panel-type radiators based on vortex generators and fin form optimization
Authors: Liu Zongjiang , Zhang Linhua , Xu Wei , Li Zhong , Feng Airong
Published: September 2023

Increasing the heat performance of heating radiators could be a valuable method for building energy conservation. This paper studied the influence of fins on the thermal performance of panel radiators (type 11). The effect of different vortex generator angles, the gap width of discontinuous fins, and different forms of staggered fins have been studied numerically and experimentally. Firstly, the simplified model of the panel radiator was analyzed by CFD simulation, the thermal performance under different geometric parameters was studied, and better geometric parameters were obtained. Research shows that optimizing the parameters of the vortex generator has a positive effect in increasing the heat dissipation of the radiator. Both discontinuous fins and staggered fins can improve the thermal performance of the radiator. The research shows that the fin shape has a significant impact on the heat dissipation of the radiator. The thermal performance of the radiator can be greatly improved by using a vortex generator with specific angles, staggered fins, and discontinuous fins. These technical routes can be directly implemented on the basis of the original radiator, which provides a direction for the technical improvement of this type of radiator.
First-Principles Simulations for the Effect of Zinc Ions on MnO2/water system
Authors: Liu Tong , Yuan Haonan , Su Yuefeng , Cao Duanyun
Published: September 2023

The aqueous zinc-ion battery (AZIB), with its excellent power density, high energy density, safety, and sustainability, is a potential energy storage device. Manganese dioxide (MnO2), as the cathode material of AZIB, has shown exceptional electrochemical performance due to its multiple valence states and outstanding ion storage performance. Nevertheless, the energy storage process of MnO2 remains controversial. In order to explain the energy storage process of MnO2 in AZIB, it is necessary to explore the effect of Zinc ions (Zn2+) on the structure of the MnO2/water interface at the atomic scale. The effect of Zn2+ on the structure of MnO2/water interface systems was examined in this work using molecular dynamics simulation. Two representative crystal phases of MnO2, including α-MnO2 and δ-MnO2, were considered. The results revealed that Zn2+ will affect the structural stability of the MnO2/water interface system, and the degree of structural deformation in MnO2 varies with its crystal phase. Moreover, Zn2+ for both the α-MnO2/water and δ-MnO2/water systems prefer to be stabilized at the interface near MnO2 and the water, forming a spinel-like product. These results offer a fresh understanding of the MnO2 energy storage process in AZIBs and can help in the development of high-performance cathode materials.
Full-Loop Study of a Pilot-Scale Dual Fluidized Bed Cold Flow System: Hydrodynamic Simulation
Authors: Chen Yexi , Xiang Wenguo
Published: September 2023

Computational particle fluid dynamics (CPFD) simulations of three-dimensional cold-flow gas-solid flow were performed for a pilot-scale dual-circulating fluidized bed (DCFB) using Barracuda Virtual Reactor® 17.4.0. This DCFB system is a fluidized bed gasifier used in a calcium-loop gasification process to produce a hydrogen-rich gas with CO2 capture. The effects of different bubble bed inlet airflow rates and different solid inventories on the full-loop pressure distribution and particle concentration distribution were compared. The increase in the bubble bed inlet airflow rate significantly increases the pressure in the bubble bed and lift pipe, and the increase in the solids inventory significantly increases the pressure where the solids are tightly packed. For long-term operation, the appropriate combination of parameters should be found to maintain a stable particle seal at the loopseals.
Offshore Electrical-Oil Production Coupling System Reliability Analysis
Authors: Wang Yongqian , Liu Liyuan , Li Shanshan , Zhou Bonan , Liu Xingyang
Published: September 2023

The role played by offshore oil resources in energy supply is becoming more and more important, and the normal operation of oil production system on offshore oil platforms requires the reliable operation of the electric power system as a prerequisite; the failure of the components in the oil production system may lead to a large-scale production shutdown, and cause the related electrical components to shut down, making the power system ineffective in a certain range. In this paper, a coupled system model of the electric power system and production system of an offshore oil platform based on massively parallel computing is proposed. By analysing the connection between the oil production system and the electric power system, the coupled system model is established and the load data are calculated. Meanwhile, the reliability model of the coupling components is established based on the fault data, and the electric-related reliability index and the production-related reliability index of the coupling system are proposed. The broad-first search (BFS) algorithm was used to determine whether the coupling nodes were powered, and the depth-first search (DFS) algorithm was used to determine the connectivity of the coupling system. In addition, a minimum load-shedding model based on the integrated fault degree is proposed to reduce the load shedding of the coupled system.
Multi-energy Complementary Power System Economic Dispatch Considering Carbon Emission and Regional User Coordination
Authors: Li Shanshan , Yang Xusong , Liu Bin
Published: September 2023

The integration of multi-energy complementarity and source-grid-load-storage is an important initiative to promote energy transformation and the high-quality development of power systems. This paper proposes a two-tier day-ahead multi-energy complementary power system economic dispatch model from the perspective of clean and low-carbon, taking into account carbon emissions and multi-regional user synergy. The model optimises the production and purchase of electricity through different decisions between the upper generation side and the lower user side, which minimises the energy production cost in the upper tier and the energy purchase cost in the lower tier, and achieves mutual benefits between the upper and lower tiers. This paper validates the algorithm and model with an improved IEEE 39-node system.
The Scaling Analysis and Numerical Simulation of Single-phase Natural Circulation
Authors: Luo Liqiang , Tao Hanzhong , Li Yannan
Published: September 2023

In this work, scaling analysis and numerical simulation of the single-phase natural circulation loop with water are presented. First, grid-dependency testing and model validation are performed. Then, according to the assumption of the boundary conditions, the effect of the heat input and structural parameters on the heat transfer characteristic is studied, including the boundary condition and temperature of the steam fluid. The results show that the scaling model can accurately express the flow heat transfer characteristics of the original model, and can reach a steady state under different working conditions. The formation of stable natural cycles is the result of coupling the boundary conditions of the heating and cooling segments under the fixed structure reference. The mass flow rate on the steady state decrease with the increase of the external fluid temperature in the cooling section, and as the heat transfer coefficient of the external convection heat transfer coefficient increases.
Benefit Analysis and Comparison of Electric Heating System for Municipal Central Heating
Authors: Qu Shipeng , Qi Liyong , Wang Fenglei , Li Zile , Xu Chen , Xiao Baihui , Qin Kaiyang
Published: September 2023

Electric heating can not only relieve the pressure of municipal central heating but also help to solve the problem of wind and light abandonment, which is an important direction for the future development of central heating. To maximize the comprehensive benefits, this paper constructs three kinds of electric heating systems. According to the comprehensive benefit evaluation of technical, economic, and environmental aspects, the comprehensive optimal scheme is selected. An office area in Beijing is taken as an example to determine the optimal scheme of electric heating and heating supplement. The results show that the comprehensive benefit of the heat pump + phase change accumulator system is the best, but the environmental benefit needs to be further improved. To promote the pace of electric heating and heating supplement, the government should increase the subsidies for electric boiler technology. At the same time, clean energy power supply enterprises should improve the trading mechanism of the electric heating market and reduce the price of clean energy heating.
Standardization proposal and product design of offshore floating photovoltaic system cables
Authors: Zhou Jialong , Liang Bin , Wang Guangliang , Jing Jixu , Li Dong , Huang Weide
Published: September 2023

The cable product for sea surface floating photovoltaic system is a waterproof cable with a highly comprehensive performance developed from the wiring application of the land photovoltaic system, which is mainly used for the electrical connection between modules of sea surface floating photovoltaic system, as well as the electrical connection of each assembly to the combiner box and combiner box to the inverter. This work introduced the main product types of photovoltaic cables in domestic and internationally, focusing on environmental adaptability, mechanical performance, and special waterproof performance analysis. On this basis, the standardization proposal for cables used in floating photovoltaic systems on the sea was proposed to facilitate the generalization, serialization, and standardization of such products, and further introduce the corresponding product design scheme, material selection, and process control, so as to provide reference for the cable manufacturing enterprises.
Research on improved linear auto-disturbance rejection control of hybrid energy storage in optical storage microgrid
Authors: Meng Lingzhao , Niu Shengsuo
Published: September 2023

Photovoltaic power generation has uncertainties such as randomness and volatility. In order to ensure the stable operation of the power system, hybrid energy storage technology is introduced to improve the voltage stability of the optical storage microgrid. Traditional PI control still needs some help in response speed and overshoot. Facing the hybrid energy storage microgrid system with nonlinear and strong coupling characteristics, in order to improve power quality and reduce bus voltage fluctuation and impact, this paper designs an improved active disturbance rejection control (ADRC) integrated energy storage control system based on a fuzzy algorithm, Based on the traditional double closed-loop PI control, the fuzzy LADRC is used to replace the voltage outer loop, and the system model is built on the MATLAB/Simulink platform for simulation. The results show that the proposed control strategy has a smaller overshoot, faster dynamic response time, and good anti-interference ability compared with the traditional PI and ADRC, which improves the dynamic performance of the photovoltaic energy storage system while stabilizing the bus voltage fluctuation and ensures the stable operation of the powergrid.
Experimental study on the energy loss from flow and electrical of vanadium battery with constant pump frequency
Authors: Sun Yanzhao , Zou Tao , Li Dianhong , Li Juntao
Published: September 2023

When the vanadium battery was running, pump frequency and current density were two frequently adjusted parameters. When the pump frequency was constant, the main flow-electrical parameter variation needs to be further studied. To this end, a 10 kW vanadium battery was built. When the current density was relatively high during the charge-discharge, the flow-electrical parameters of the cathode and anode including the temperature, flow resistance, turning voltage difference, capacity loss, energy loss and energy efficiency were studied. Besides, the compositions of capacity and energy were introduced, and the loss calculation scheme was proposed. Firstly, in flow analysis, the flow resistance was defined, which represents the flow state of the electrolyte. It was found that the flow resistance was nearly linear with the temperature. Secondly, in electric analysis, the turning voltage difference increased with the current density increasing. For the same current density, the total energy loss of charge was less than the discharge, and the energy loss of bypass was less than the internal resistance. With the current density increasing, the energy efficiency decreased. The research can be provided insight into the optimizing operation for the vanadium battery.
Remaining useful life prediction of sodium-ion batteries based on ICEEMDAN-CNN-GRU
Authors: Shi Yongsheng , Zhai Xinran , Hu Yujun
Published: September 2023

A hybrid battery remaining useful life (RUL) prediction model based on ICEEMDAN-CNN-GRU(M1) is proposed to address the nonlinearity and complexity of capacity degradation in sodium-ion batteries. Firstly, capacity attenuation data and some indirect parameters easily obtainable by sensors are experimentally measured. The original capacity sequence is reconstructed into a new one using the ICEEMDAN method to effectively suppress the influence of capacity regeneration and noise signals. Secondly, a hybrid CNN-GRU prediction model is constructed by leveraging the advantages of convolutional neural networks (CNN) in the field of data mining and gated recurrent unit (GRU) in time series prediction. Three sets of indirect parameters are used as inputs, and the reconstructed capacity is used as the output for RUL prediction model training with different starting points. Finally, the effectiveness of the algorithm is verified through data from three different rates, and the predicted indicators are better than those of traditional algorithms such as GRU, LSTM, and SVM.
A study of power storage configurations in residential communities in multiple scenarios accounting for battery degradation
Authors: Shang Liqun , Zhang Jiantao , Min Pengbo , Li Hongbo , Hou Yadong
Published: September 2023

The peak and valley load differences in residential communities are large, and there is a timing difference between the peak hours of load and photovoltaic power generation. As a result, power storage system deployment can employ photovoltaic output to lessen peak and valley load discrepancies. To make power storage design in residential areas more feasible, the research initially examines the influence of charging and discharging rate and depth on the life of power storage batteries to develop a dynamic loss model for power storage batteries and estimate the operational life of the system; secondly, as the goal function, the largest yearly net revenue is used to optimize the optimization of the power storage system; finally uses particle swarm algorithm to simulate the power storage system in residential communities under different operational scenarios. The results indicate that the residential district power storage system is more effective in the grid-connected scenario and validate the reasonableness and effectiveness of the model used, providing a reference for the planning and construction of residential district power storage systems.
Corrugation-like Triboelectric Nanogenerators Integrated Buoys for Wave Energy Harvesting
Authors: Guan Tangzhen , Wang Weichen , Wang Xinyu , Wen Chengxuan , Xu Ruijiang , Zhu Chuanqing , Zou Tao , Zheng Jiaxi , Xu Minyi , Wang Hao
Published: September 2023

Marine buoys, as the nodes of the marine monitoring system, play a vital role in monitoring marine activities, which can collect hydro-meteorological information for marine scientific research, offshore oil development, and construction of marine ports. However, sustainable and cost-effective power supply for marine buoys equipped with electrical devices is still a challenge. In this paper, the corrugation-like triboelectric nanogenerator (C-TENG) integrated with marine buoys was proposed, aiming at harvesting wave energy and powering marine buoys. The C-TENG consisting of corrugated plates, corrugation-like channels, aluminum electrodes, barrier sheets, flat plates, and polytetrafluoroethylene (PTFE) pellets, was capable of effectively converting the energy harnessed from waves into electricity. As a result of the ocean wave’s excitement, the sliding contact between the PTFE pellets and the aluminum electrode produced electron transfer via the triboelectrification effect and electrostatic induction. With the unique corrugation-like channels, the output of the devices was in the same phase, avoiding the electrical loss resulting from rectification. Furthermore, the power density of the 5 layers parallel-connected C-TENG units reached 21.95 W/m3, which was approximately 300% higher than the previous tower-like TENG. The experimental results prove that the proposed C-TENG may provide a possible solution for wave energy harvesting and marine buoy powering.
Optimal Scheduling Study of Multi-Source Power Generation System with an Electric Heating Unit
Authors: Yang Xiong , Zhang Xiaohong
Published: September 2023

This paper proposes an optimal dispatching strategy for a multi-source power generation system containing electric heating devices. A multi-source co-generation system model containing electric heating devices is constructed with the minimum integrated operating cost and the minimum variance of system output power as the multi-objective functions, and the system operating constraints and heat storage constraints as the constraints. A greedy algorithm is introduced and an improved NSGA-II algorithm is proposed to solve the model. After comparison, the integrated operation cost of the multi-source co-generation system with an electric heating device is reduced by 11.35%, the scenery utilization rate is increased by 22.15%, and the total power output volatility is reduced by 29.18%. The results verify the effectiveness and accuracy of the proposed optimal scheduling strategy and the improved algorithm.
An energy storage configuration planning strategy considering photovoltaic consumption
Authors: Zhou Zi Jian
Published: September 2023

The extensive access to new energy resources will influence the grid’s economic operation and reliable power supply. This text considers the planning problem of the power company’s configuration in the energy-storage system. And the planning goal is to maximize the comprehensive benefits of the power company. The comprehensive benefit model of new energy resource costs and related revenue of power companies, as well as the operational characteristics of photovoltaic and energy-storage equipments, is analyzed, and a comprehensive operational strategy for energy storage systems is constructed. Optimizing energy storage configuration plans and operational strategies for power companies can improve the operations’ economic benefits and the utilization level of new energy generation.
Low Frequency Oscillation Suppression Strategy in New Power System Based on Virtual Synchronous Generator
Authors: Lu Shengyang , Zhang Wuyang , Han Deyun , Wang Huibin , Meng Linglin , Yan Zhenhong , Cai Yupeng , Wang Haixin , Yang Junyou , Sui Yuqiu
Published: September 2023

With the blend of massive new energy into power network systems, the inertia and damping features of new power systems are reduced, which is prone to cause low-frequency oscillations (LFO) in the power systems. Virtual synchronous generators (VSG) have received widespread attention by simulating the external characteristics of synchronous generators (SG) to enhance the inertia of new power systems and help suppress low-frequency oscillations. By analyzing the mathematical model of VSG, the control links of each part of VSG are established, the traditional reactive power-voltage (Q-V) of VSG is improved, and the formulas of active voltage control and reactive power control droop coefficient are deduced.

Finally, a simulation model of VSG is created by MATLAB/Simulink platform, and new methods for suppressing LFO in power systems are compared and analyzed. The correctness of the formula and the improvement effect of reactive power and voltage control are verified.
Research on Regional Spot Market Clearing Model Considering Subregional Power Exchange Constraints
Authors: Du Fei , Hu Rong , Liu Zhong , Zhang Xipeng , Zhang Rui
Published: September 2023

The goal of the power market is to optimize the allocation of power resources. The regional power spot market can expand the space of market optimization, which makes each sub-regional demand and resource sufficiently complemented, and it is an important part of the power spot market. The difficulty of clearing the regional spot market lies in the following two aspects. One is to take into account the different power market models of each sub-region, and the other is that the regional clearing results can ensure the safety of the power system in each sub-region. This article proposes a dual-layer model that contains the power exchange constraints of the sub-region. Its boundary conditions that are based on the unit commitment results of each sub-region clearing model are used for regional spot market clearing. It is compatible with the possible power spot market model of each sub-region, but also fully considers the clearance of the sub-region. At the same time, it ensures that the regional clearing results will not affect the safe operation of the system in each sub-region. The article verifies the validity of the design area through calculation, and analyzes the clearing effect of the regional market.
Location and Layout of Electric Vehicle Charging Stations Based on K-Means Algorithm
Authors: Zhou Jixiang , Wang Ruixing , Huang Weijian , Zhao Zhong , Zheng Fengfeng , Wang Zhiyun
Published: September 2023

The development of the electric vehicle industry can be promoted by the reasonable layout of electric vehicle charging stations. In this study, the construction of charging piles for new energy vehicles in Guangzhou was discussed. Specifically, the location of the charging pile clustering center was selected using the K-Means clustering algorithm. The K-Means clustering results were analyzed through the elbow method to solve the optimal construction partition of charging piles. Simulation modeling revealed that when k=6, charging piles could be used more conveniently when being about 4.8665 km from the dense flow of new energy vehicles under the clustering center mode compared with the situation at the original distance.
Transformer winding mechanical fault diagnosis method based on closing transient acoustic vibration signal
Authors: Song Le , Chen Jiyao
Published: September 2023

The current conventional transformer winding fault diagnosis method mainly extracts the vibration signal through the time-frequency analysis method, which leads to poor diagnosis due to the lack of analysis of the transformer winding state. In this regard, a transformer winding mechanical fault diagnosis method based on the closing transient acoustic vibration signal is proposed. The closing vibration signals of the transformer in the normal and loose winding states are collected separately, the transformer winding force situation is analysed, and the transformer fault signal characteristics are extracted and combined with a fault classifier to construct a fault diagnosis model. In the experiments, the proposed method is verified for fault identification. The experimental results show that the proposed method has a high correct rate when used to identify different types of transformer faults, and has a more desirable fault diagnosis performance.
Research on Parallel Control Strategy of Grid-forming of Power Conversion System
Authors: Zhou Jinghua , Yan Hao
Published: September 2023

A high proportion of power electronic equipment, distributed energy, and other new energy access to the grid system, low inertia and low damping to the power grid system, these kinds of power grid characteristics in power electric wire aging remote mountains or island areas, therefore, need energy storage system under the microgrid can provide inertial support for load or grid, improve the system damping characteristics. On this basis, the grid-forming control is proposed, so that the power conversion system can work under the off-grid, and can provide inertia and damping to maintain the system stability. In addition, large-scale energy storage systems often require multiple machines operating in parallel. In this paper, the topology of NPC for a power conversion system is studied and analyzed in off-grid mode.
Fault diagnosis model of main equipment in substation based on multi-mode time-frequency combination
Authors: Zheng Peihao , Dou Guoxian , Gao Liang
Published: September 2023

The conventional fault diagnosis method of the main equipment in substations has strong limitations and the fault diagnosis accuracy is low, so this paper introduces the multi-mode time-frequency combination method and designs the fault diagnosis model of the main equipment in substations. First, the transmission mode of fault information of main transformer equipment is analyzed and the fault source is diagnosed. Secondly, the UHF partial discharge method is used to detect the partial discharge signal of the main substation equipment. On this basis, the main equipment fault diagnosis model of the substation is established based on the multi-mode time-frequency combination, and the equipment fault degree is obtained to complete the fault diagnosis. According to the experimental results, the proposed fault diagnosis model is highly feasible, and the accuracy of an insulation fault, overheating fault and discharge fault diagnosis is more than 98%.
Harmonic Loss Calculation Method Based on Fourier Expansion for HVDC System Transformer
Authors: Peng Guangqiang , Huang Zhidi , Xing Yue , Wu Jiyang , He Jingsong , Yan Jing
Published: September 2023

The harmonics generated by devices in HVDC (High Voltage Direct Current) system and the harmonics input at the grid side have a great impact on the loss assessment of the converter transformer. Therefore, this paper proposes a simplified and efficient harmonic loss algorithm based on the classical transformer harmonic model, and Fourier transform and generates the code in MATLAB software. Practical engineering examples have proved that the proposed algorithm can accurately calculate the load loss and harmonic loss of the rheology by filtering data in the HVDC system. Therefore, it can solve the problems such as unclear calculation of harmonic resistance in existing standard theoretical algorithms or difficulty in obtaining test data of stray loss and eddy current loss at the fundamental frequency.
Reactive Capability Sizing of HPR1000 NPP in the UK Grid
Authors: Zhang Qingliang , Ye Yulin , Zhang Ping , Liu Sen
Published: September 2023

To address the voltage profile, the reactive power requirements in the UK Grid Code have risen due to increasing power flows and the wind turbine system volume. This study strives to figure out the reactive capability of HPR1000 NPP in the UK grid and presents ETAP-based modeling and simulation of the demonstration. The paper first introduces the UK grid’s reactive capability requirements, then analyses the theory of synchronous generator reactive capability and unit transformer tap changer sizing, and finally demonstrates the sizing of reactive generator capability and unit transformer tap changer via load flow studies. The reactive capability requirements of the UK grid are more severe than China, causing the synchronous generator with a larger reactive capability [0.83PF(lagging), 0.98PF(leading)] and the unit transformer with a larger range of on-load tap changer[-10×1.25% / +4×1.25%], which should be concerned during HPR1000 NPP exportation.
Electromagnetic Transient Modeling Method of Photovoltaic Power Station Based on FPGA
Authors: Guo Qi , Li Shengke , Xia Shiwei , Guo Haiping , Li Shuyong
Published: September 2023

The rapid development of renewable energy needs the effective support of simulation technology. Aiming at the shortage of both modeling scale and simulation accuracy of the current large-scale photovoltaic power station, an electromagnetic transient modeling and real-time simulation method suitable for large-scale photovoltaic power stations are proposed. The microsecond accurate real-time simulation of 24 photovoltaic power units is implemented on a single FPGA. Through an equivalent modeling method, the electromagnetic transient model of a photovoltaic power unit including a PV array, DC boost circuit, grid-connected inverter, filter, and grid-side transformer is established. Then, based on the FPGA parallel computing and pipeline time division multiplexing technology, the updating framework of the station collecting network and the power unit is constructed, and the real-time simulation model of the station including 24 photovoltaic power units in 4 sub-stations is built. Finally, the microsecond real-time simulation of the photovoltaic power station is realized through RTRES, a self-developed real-time simulator in China’s Southern Power Grid. The comparison with the detailed PSCAD model shows that the simulation error is within ± 2%, which verifies the correctness of the proposed method and model.
Transient Analysis and Prevention Measures of Lightning Strikes on Step-up Transformers in Wind Farms
Authors: Yang Bin
Published: September 2023

Wind farms are mainly located in open and windy mountainous areas with complex climatic and topographic conditions, and the operation of equipment is inevitably affected by thunderstorms. In this paper, an electromagnetic transient analysis model for lightning strikes on collector lines is established with the use of the ATP-EMTP software. The overvoltage situation of step-up transformers subjected to lightning strikes on towers is analysed, and it is pointed out that existing lightning protection measures cannot effectively prevent the three-phase invasion caused by large current lightning, and a lightning protection strategy of installing a set of lightning arresters in the 35 kV bushing of the main transformer is proposed. A transformer trapezoidal equivalent circuit analysis model is established, and the effectiveness of the lightning protection measures are verified through simulation calculations, providing a technical reference for lightning protection in wind farms in multi-thunderstorm areas.
Reactive Power Optimization of Sub-Blubber Rod in Active Distribution Network Based on Improved Grey Markov Model
Authors: Qi Fang , Song Zhuoran , Guo Yong , Liu Cong , Li Jianfeng , Yu Jia
Published: September 2023

A wattless power optimization method for active energy distribution networks based on an improved grey Markov model was studied to improve the voltage drop caused by unreasonable wattless power distribution in centralized electricity supply modes. Select the normalized residual sequence method to modify the non-biased grey GM(1,1) model, use the non-biased grey GM(1,1) model that has completed the residual correction to obtain the system voltage index sequence, and use the Markov model to divide the system voltage index sequence Use the Markov state to establish an improved grey Markov model to obtain the prediction results of the system voltage of centralized electricity supply mode; take the lowest deviation of the system voltage prediction control as the goal, and establish the goal of the wattless power output of centralized electricity supply mode Function to solve the objective function under the condition of satisfying the system voltage constraint and the wattless power adjustment capacity constraint of centralized electricity supply mode, and realize the wattless power optimization of centralized electricity supply mode. The case analysis results indicate that this research method can achieve wattless power optimization of distribution networks.
Wind induced coupling effects of transmission tower-line system at microtopography
Authors: Zhong Weijun , Yao Jianfeng , Tu Zhibin , Xu Haiwei
Published: September 2023

The coupled and uncoupled Dynamic Finite Element Models (DFEMs) of the transmission tower-line system consisting of two towers and three spans of conductors and ground wires were built at the windward and crosswind slope of a cosinoidal hill. The acceleration ratios of mean wind profiles of cosinoidal mountains were summarized from previous studies, then the mean wind profile over the windward, crosswind and leeward slopes were revised. The wind loads acting on the transmission tower-line system were calculated based on the revised profile. The wind-induced dynamic responses of the coupled and uncoupled DFEMs were detected, and the coupling effects on reaction force of hanging points, displacements and accelerations at the tower top, axial forces of main rods and wind-induced vibration coefficients were analysed. The results show that due to the lack of the TMD-like effect, the uncoupled system is more sensitive to wind load and has significant wind-induced vibration compared to the coupled system, making the three-dimensional force of the hanging point, displacements and accelerations at the tower top, axial forces of main rods increasing, but the wind-induced vibration coefficients change little. Generally, the coupling effects of the tower-line system are significant. Ignoring it will make the structural design of transmission towers conservative.
Hybrid Power Retrofitting Study for a Platform Supply Vessel
Authors: Wang Xincai , Gao Haibo , Li Cheng , Sun Yubo , Yan Junhui , Sun Wanfeng
Published: September 2023

This paper takes a platform supply vessel as the parent vessel and introduces its power system configuration and working conditions; to meet the requirements of carbon emissions reduction and improve economic efficiency, a preliminary program of marine hybrid power retrofitting of diesel generator sets assisted with Lithium battery module is proposed on the base of analyzing its working conditions, the fuel consumptions and carbon emissions are compared between before and after the retrofitting, etc. According to the calculation results, the paper concludes that the investment payback period of the refitting is about 6.38 years, and this refitting will have good economic benefits and social benefits.
The Influence of Decentralized Charging Pile Connection on Voltage Deviation of Distribution Network
Authors: Tang Zhirui
Published: September 2023

In this study, a mathematical model was developed to describe the charging process of a charging pile. The PWM charging process was determined, and a mathematical model for the DC-DC output of the charging pile was constructed. Prior to the photovoltaic connection, the voltage distribution of the distribution network was determined, and the line voltage drop was obtained. The impact of the access capacity of distributed charging piles on the voltage of the distribution network was analyzed. Furthermore, the line voltage drop between nodes was determined, and the nodes were balanced to calculate the voltage of each node at this time. This analysis enabled the investigation of the impact of distributed charging pile access on the voltage deviation of the distribution network. The results indicate that the calculation error of voltage deviation in the distribution network is only 0.002, with a maximum prediction accuracy of 99.0%.