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2021 Vol. 8, No. 3

Cover & Contents
2021, 8(3): 1-130.
Reviews & Progress
Impact and Harm Mitigation of Offshore Wind Farms on Birds
Ren HU, Jinshao YE, Yongle QI
2021, 8(3): 1-7. doi: 10.16516/j.gedi.issn2095-8676.2021.03.001
  Introduction  Wind energy, widely recognized as one of the most mature renewable energy technologies, has developed rapidly in recent years. Over the past years, China has developed a large number of offshore wind power projects. However, the impact of wind farms on the environment, especially on birds, has caused a lot of concern and research. Before reaching the CO2 emission peak, the offshore wind energy industry will continue to grow in China. Therefore, it is necessary to fully understand the impact of wind farms on birds.  Method  Based on the summary of the existing research, this paper reviewed problems concerning birds caused by offshore wind farms, and discussed the prevention and mitigation measures that can minimize the adverse environmental impacts on birds.  Result  The results showed that wind farms have harmed the survival of birds mainly by wind turbine blade striking and wind turbine operation noises. There is no clear evidence so far that birds are affected by electromagnetic fields. The operation of wind farms may cause changes of birds' habitats, hindering of birds' reproduction and communication, and changes in population structure. People can reduce the adverse effects of wind farms on birds by means of wind farm site selection, wind farm reshape, wind turbine blade and pile crane structure design, remote sensing and video surveillance, etc.  Conclusion  By conducting profounder research on birds in wind farms, it is beneficial for us to master basic laws of bird ecology relevant to the development, construction and operation of offshore wind farms and make scientific strategies that can reduce adverse effects on ecological environment.
Challenges and Prospects for the Trends of Power Structure Adjustment Under the Goal of Carbon Peak and Neutrality
Shaokuan CAI
2021, 8(3): 8-17. doi: 10.16516/j.gedi.issn2095-8676.2021.03.002
  Introduction  "Carbon peak and neutrality" is an important strategic decision to promote the transformation of China's energy economy and build a community of shared future for mankind. China is a big energy consuming country and the whole society is facing huge challenges under the "carbon peak and neutrality" goal. The realization of the goal requires the guidance of correct theoretical methods and scientific deployment.  Method  For this reason, based on China's energy development situation, the essence of the "carbon peak and neutrality" goal was analyzed, the fundamental way to achieve the goal was given from a macro level, the development trends of power load such as zero-carbon energy power generation load composition and load demand indicators under the "carbon peak and neutrality" were predicted from the perspective of the energy supply side, and a new concept of "equivalent electric energy substitution" was proposed in this article.  Result  Based on the resource endowments of nuclear energy, hydropower, wind energy, solar energy and other resources, the power structure adjustment scheme under the "carbon peak and neutrality" goal was given, and the system operation characteristics problems caused by the power structure adjustment were analyzed, and measures to solve the problems were provided.  Conclusion  The "carbon peak and neutrality" goal may set off a new generation of energy revolution and a comprehensive industrial revolution. The four main zero-carbon energy resources of water, wind, light, and nuclear can meet the needs of China's sustainable social and economic development, and new energy will usher in an era of rapid development. This article discusses the development trend of future energy from many aspects, and gives constructive opinions on the adjustment of power structure, which has important theoretical guiding significance for the realization of the "carbon peak and neutrality" goal.
Offshore Wind Power
Design and Research on the Foundation Damping Structure of Semi-Submersible Floating Offshore Wind Turbines
Jiahao CHEN, Ziwei YIN, Rongkuan ZHU, Zhaorong MA, Xuejiao JING, Yan LI
2021, 8(3): 18-25. doi: 10.16516/j.gedi.issn2095-8676.2021.03.003
  Introduction  In order to find an economic and effective solution to the improvement of the hydrodynamic performance of floating offshore wind turbines, this paper studies the design scheme of heave plates to improve the hydrodynamic damping performance and anti-rolling effect of the floating body, and finally improve the stability of the output power of floating offshore wind turbines.  Method  Taking a 10 MW semi-submersible floating wind turbine as an example, this paper discussed the effect of different design parameters of the heave plate structure on improving the hydrodynamic damping using the method of computational fluid dynamics, and found an optimal design scheme.  Result  After optimized design, the heave damping of the heave plate structure is increased by 14.9%, and the roll damping is increased by 19.1%, and while the heave damping of the “quincunx-shaped” edge heave plate is increased by 36.98% compared with the original model.  Conclusion  This paper reveals the formation mechanism of the generation of vortex vents and the improvement of the hydrodynamic damping of the heave plate, and puts forward the “quincunx-shaped” heave plate structure in an innovative manner that can effectively improve the damping performance of the heave motion of the floating body. The above conclusions provide important references for the research and design of the foundation structure of the floating offshore wind turbines of this kind in the future.
Structural Finite Element Simulation and Evaluation Method for Ship Collision Damage and Residual Strength of the Jacket
Hao REN, Hui FANG, Xinze WEI
2021, 8(3): 26-33. doi: 10.16516/j.gedi.issn2095-8676.2021.03.004
  Introduction  The vessel collision of jacket foundation in an offshore wind farm in the South China Sea happens frequently. Under this circumstance, the accurate assessment of the residual strength after structural damage has become an important technology of the safety of wind farm operation and maintenance.  Method  Based on the actual jacket structure of a wind farm in the South China Sea and considering the actual ship operation situation in the sea area, this paper used the finite element software ABAQUS to simulate the ship collision damage process of jacket foundation under different combinations of ship mass, initial velocity and collision angle.  Result  By using the quasi static method, the time interval of the collision forces and the plastic strain contours of the key nodes under different working conditions are concluded. Besides, the relationship between the maximum impact forces and impact factors and typical characteristics of the damage are concluded.  Conclusion  Based on the analysis, the typical change laws of the residual strength after the ship collision of the jacket are concluded to provide technological support for rapid assessment of the collision damage of related structures in the actual engineering process.
Numerical Simulation Research on the Horizontal Bearing Capacity of Rock-Socketed Piles for Offshore Wind Turbines
Li ZHANG, Yue HUANG, Hongqing WANG, Xueliang ZHAO, Jingfei ZHANG
2021, 8(3): 34-43. doi: 10.16516/j.gedi.issn2095-8676.2021.03.005
  Introduction  The aim of this paper is to analyze the influence of the size and the vertical load of the pile foundation on the horizontal bearing capacity of rock-socketed piles.  Method  Based on a field test of the rock-socketed concrete pile under horizontal load, a 3-D finite difference numerical model was established and parametric analyses were performed.  Result  The results show that there is a critical rock-socketed length (ratio of length and diameter) for rock-socketed piles. Changes of the size of the pile will influence the relative stiffness of the pile and the rock, which will affect the critical rock-socketed length. With the decrease of the pile diameter, the critical socket length will increase. Within the scope of the bearing capacity of the pile and under the condition of combined vertical and horizontal load, the horizontal displacement and bending moment of the pile will have a pretty large decrease. This influence will be neglected if the vertical friction is assumed to be the same on the both sides of the pile or simplified to be at the center of the pile, which will cause error to the calculation results.  Conclusion  This study is supposed to provide contribution to the reasonable design and further research of the horizontal load of rock-socketed piles.
Numerical Simulation Research on the Vertical Bearing Capacity of the Single Pile Foundation in Zhugensha Sea Area
Qiang ZHANG, Chang GE, Xiaolei SHEN, Jin SHANG
2021, 8(3): 44-50. doi: 10.16516/j.gedi.issn2095-8676.2021.03.006
  Introduction  Wind power projects in Jiangsu Province are mainly located in the offshore radiant sandbank sea area. It is of great significance to study the bearing capacity of the large diameter single pile in this stratum.  Method  Based on the test pile test of the steel pipe pile in the radiant sandbank area, the FLAC3D numerical model of the single pile foundation was established, and the numerical simulation study of bearing performance of steel pipe pile foundations with different diameters was carried out.  Result  The results show that: The vertical load-displacement (Q-s curve of the steel pipe obtained by FLAC3D numerical simulation is basically consistent with the change trend of the measured curve; as the burial depth increases, the axial force of the pile body below the mud surface continuously decreases. Most of the axial bearing capacity is provided by the pile side friction, and the axial bearing capacity borne by the pile tip resistance is relatively small; the pile diameter and the ultimate vertical bearing capacity of steel pipe piles conform to a non-sexual relationship. The ultimate vertical bearing capacity of a single pile increases with the increase of the pile diameter. When the pile diameter increases by 2 times, the corresponding vertical ultimate load increases by 3 times.  Conclusion  The corresponding results can provide reference for practical engineering.
Application of Multi-Beam Sounding System in Offshore Wind Farm Survey
Xinhua LIU, Meng WU
2021, 8(3): 51-57. doi: 10.16516/j.gedi.issn2095-8676.2021.03.007
  Introduction  In order to obtain detailed seafloor topographical information, an application of multi-beam sounding system in offshore wind farm survey is proposed.  Method  Taking an offshore floating wind power equipment development project as an example, the principle and composition of the Reson SeaBat T50-P multi-beam sounding system were introduced in detail, through the implementation of the project, the results were analyzed and the accuracy was evaluated.  Result  Through the practical application of this project, it is verified that the multi-beam sounding system has better convenience, high efficiency and reliability in the offshore wind farm survey.  Conclusion  The practice of this project provides a good reference for other similar offshore wind farm surveys.
Energy Storage Technology
Research on Application of Energy Storage System for Data Center
Yu ZHOU, Weihan HAO
2021, 8(3): 58-62. doi: 10.16516/j.gedi.issn2095-8676.2021.03.008
  Introduction  Under the background of new infrastructure, data centers have developed rapidly. As a high-density load, how to maximize the use of clean energy and reduce operating energy consumption has been more concerned in data centerprojects.  Method  The main battery technical parameters of energy storage system and the power supply requirements of the data center were given in the paper.  Result  Through battery parameter analysis, recommendations for battery selection suitable for data center energy storage systems are given, and then the application modes for data center energy storage systems and the energy storage system topology with the fast switching function are proposed.  Conclusion  We verify the effectiveness of this technical solution through typical project case.
Flexible Modification Technology and Application Prospect of Thermal Power Unit Based on High Temperature Molten Salt Heat Storage
Jun LI, Peiwang ZHU, Hui WANG, Xiaolong QIU
2021, 8(3): 63-70. doi: 10.16516/j.gedi.issn2095-8676.2021.03.009
  Introduction  Through the analysis of the exsiting problems in conventional flexibility modification technology of thermal power units, a new type of flexibility modification technology is proposed, which is to embed a large-capacity high-temperature molten salt heat storage system in the traditional "boiler-turbine" thermal system. It weakens the original rigid connection of boiler-turbine coupling to achieve deep peak regulation and flexible operation of thermal power units.  Method  According to the different thermal characteristics of steam, water and molten salt, an integrated thermal system of "boiler-high temperature heat storage-steam engine" was established by thermal balance calculation.  Result  The results show that the deep peak regulation capability of thermal power unit is greatly improved after configuring high-temperature molten salt heat storage system, and the problems of conventional modification methods can be solved. At the same time, the ability of the units to provide high-parameter industrial steam will be greatly improved. This will effectively improve the economic efficiency of power plants and make up for the lack of peak regulation compensation mechanism. High-temperature molten salt heat storage technology can also be applied to the life extension of thermal power plants, not only increasing the grid's flexible peak regulation power supply, but also enabling old power plant enterprise assets continue to create benefits.  Conclusion  After a batch of thermal power units in the grid are modified by large-scale high-temperature molten salt heat storage technology, a large number of flexible peak regulation power sources are provided for the grid, without increasing the total coal consumption and effectively alleviating the problem of new energy power consumption. Meanwhile, steam turbines and generators are reserved, which can provide backup capacity and moment of inertia for the power system, to ensure the safety and stability of the power supply and the grid. The promotion of this technology will effectively promote the upgrading of thermal power plants and help achieve the goal of "carbon neutrality and carbon peak".
Research on Enhancing Heat Transfer Performance by BTES Hot and Cold Partition
Zheng LIU, Xinnan OUYANG, Shaoyong LIU, Yongan CHEN
2021, 8(3): 71-77. doi: 10.16516/j.gedi.issn2095-8676.2021.03.010
  Introduction  Borehole Thermal Energy Storage (BTES: Borehole Thermal Energy Storage) refers to a borehole closed cycle system that uses the heat capacity of underground soil, rocks and water to store energy. The main feature is the use of cold and hot partitioned layouts and intelligent control methods. Innovative development and utilization combined with domestic geology. In order to study the feasibility of using cold and hot zones to improve the heat transfer effect of buried pipes, a single U-shaped buried pipe heat exchanger borehole was established based on the theory of porous media heat transfer, energy conservation, and finite length non-moving line heat source model. Internal and external mathematical models are analyzed and verified by numerical simulation methods.  Method  Based on the common soil cold and hot accumulation phenomenon, by changing the order of the medium in the pipe flowing through the two divided areas, it becomes passive to prevent and control cold and heat accumulation In order to actively deploy energy storage for cross-season utilization, so as to actively generate cold and hot accumulation energy storage in the two divided areas, which are defined as "cold zone" and "hot zone".  Result  After numerical simulation analysis, the phenomenon of thermal accumulation occurs The heat exchange rate of the "hot zone" during the heating period increases year by year. As far as the maximum heat exchange rate is concerned, the second year will increase by 319 W compared to the first year, and the third year will increase by 308 W compared with the second year; cold accumulation occurs. The amount of heat exchange in the "cold zone" during the refrigeration period increases year by year. In terms of the maximum heat exchange rate, the second year will increase by 209 W compared with the first year, and the third year will increase by 198 W compared with the second year.  Conclusion  The above results show that this method can enhance the heat transfer effect of the buried heat exchanger. The alternate use of the two areas during the heating period and the cooling period not only effectively solves the energy efficiency degradation caused by the imbalance of cold and heat of the ground source heat pump system, but also improves the heat exchange effect of the system while reducing the perforated space.
Research on Energy Storage Market Under the Power Marketing Environment in Southern China
Jia RAO, Bin YI
2021, 8(3): 78-83. doi: 10.16516/j.gedi.issn2095-8676.2021.03.011
  Introduction   With the advancement of clean energy transformation and power marketization reform, the policy mechanism and market environment of electricity energy storage in the southern region have gone into a good situation constantly.   Method   This paper studied the electric auxiliary service market and demand response market rules related to the energy storage in the southern region, analyzed the development trend of the energy storage market in the southern region from the four aspects of the auxiliary service transaction varieties, user-side demand response, new energy distribution energy and independent energy storage stations, etc. We used the user-side energy storage investment operation economy as an example to perform the quantitative analysis.   Result   The research shows that under the competitive conditions of the power marketing market, the greater the demand for frequency modulation, peak shaving, and the lack of flexible resources adjustment, the greater the contribution of energy storage to auxiliary services or demand response to the system, so as the comprehensive benefits.   Conclusion   This paper can provide ideas for power energy storage business model innovation and application promotion.
Nuclear Power Generation
Design Research on Steam Drain System of Fast Reactor Nuclear Power Plants
Yan LIN, Daohong YANG, Haiyun SHI
2021, 8(3): 84-88. doi: 10.16516/j.gedi.issn2095-8676.2021.03.012
  Introduction  The steam parameters of sodium-cooled fast reactor is different from PWR nuclear power or conventional fossil-fuel power plant, so it's necessary to restudy the drain system.  Method  Specific to PWR nuclear power plant or conventional fossil-fuel power plant, the steam drain system was collated and discussed from aspects such as the components and control logic.  Result  Then an optimized system is developed for fast reactor power unit based on the above analysis result and the characteristics of the steam system.  Conclusion  The result shows that the optimized drain system can meet with the requirement of fast reactor power unit, and it also can be a reference for construction of future reactor units.
Thermal Power Generation
Research on Ecological Design of the Urban Gas Turbine Power Plant with the Garden Style
Xiaolan LÜ, Sixiong LIAO, Yujun LI
2021, 8(3): 89-94. doi: 10.16516/j.gedi.issn2095-8676.2021.03.013
  Introduction  With the development of the clean electric power industry, the construction of gas turbine power plants has become an important part of regional planning of urban areas. As a huge industrial building complex, how to shape its image, make it a large landscape complex, and enhance the surroundings with the positive effects of ecology, harmony, nature and environmental protection has become a new direction and inevitable trend in the design of gas turbine power plants today.  Method  At the beginning of the design, the goal of landscape and ecological design was determined for the whole complex and environment of the plant, the overall landscape design of each building was carried out, and the concept of ecological design was integrated.  Result  Based on the project of Huaneng Gas Turbine Power Plant in Dongguan, the consideration of layout optimization and the design concept of landscape optimization of the whole plant are analyzed to create a modernized garden-style power plant with novel architecture, beautified scenery, fresh environment and fine ecology.  Conclusion  The proposed implementation path can be a reference for the design of similar power plants in the future.
Analysis on the De-Industrialization Design of Huangpu Gas Turbine Power Plant
Jie LI
2021, 8(3): 95-103. doi: 10.16516/j.gedi.issn2095-8676.2021.03.014
  Introduction  With the development of cities, power plants gradually change from "outside" to "inside". Single architectural design can no longer meet the design of power plants in cities. Taking Huangpu Power Plant as an example, it can provide reference for the design of and the same type of urban gas turbine power plants.  Method  By analysis, integration and utilization, various unfavorable factors were transformed into the elements of de-industrialization for the power plant, which enriched the connotations of de-industrialization design.  Result  The paper analyzed the detailed design concepts and methods of land use, architectural surface, noise reduction and landscape, etc. for Huangpu Power Plant.  Conclusion  As an urban gas turbine power plant, Huangpu Power Plant shows the concept of de-industrialization, which extends the scope of modern industrial architecture design and provides more diversified design techniques.
Research and Application of Chemical Ammonia Dosing System and Its Safety Technology for Large-Scale Combined Cycle Power Plant
Xiaohui JI
2021, 8(3): 104-108. doi: 10.16516/j.gedi.issn2095-8676.2021.03.015
  Introduction  Through the technical and economic comparison of two ways of chemical dosing liquid ammonia and ammonia water for a large-scale combined cycle power plant in Guangdong Province, it is proposed that the water quality control index of condensate and feed water in the way of adding liquid ammonia is prior to the way of adding ammonia water. In addition, adding liquid ammonia can improve the corrosion resistance of the thermal system equipment and pipelines, and is beneficial to the safe and stable operation of the whole unit. Moreover, the consumption and operation cost of liquid ammonia are lower and the technical and economic benefits are more effective.  Method  In order to ensure the safe operation of liquid ammonia storage tank and prevent safe accidents, combined with the current national and local regulations and standards, this paper provided the safety technology design and measures for liquid ammonia system.  Result  This paper summarizes the key technology and innovative points of safety design for liquid ammonia system.  Conclusion  Therefore, it can play a reference role for the design of similar projects in the future.
Research on Steam-Water Quality Control for Ultra-Supercritical Power Plant
Shaojie LI, Qunxing TAN
2021, 8(3): 109-113. doi: 10.16516/j.gedi.issn2095-8676.2021.03.016
  Introduction  The ultra-supercritical unit is the main power generation unit in China, which has strict requirements on water steam quality. In this paper, water steam quality control measures have been proposed to prevent scaling and corrosion of the thermal system and ensure safe and economic operation of the unit.  Method  To control the steam-water quality of ultra-supercritical units, proper demineralized water production process, reliable condensate polishing system, feedwater oxygenation treatment (OT), reasonable on-line monitoring meter, appropriate condenser pipe and shutdown protection were selected.  Result  The above measures can effectively prevent scaling and corrosion of the thermal system and ensure the safe and economic operation of the unit.  Conclusion  The steam-water quality control of ultra-supercritical parameters units can refer to the Water Vapor Quality of Thermal Power Units and Steam Power Equipment (GB/T 12145—2016), and it is recommended to control the Parameters according to the expected value.
Optimization and Improvement of Frequency Modulation Auxiliary Service Control System for the 700 MW Unit
Qiang LI
2021, 8(3): 114-121. doi: 10.16516/j.gedi.issn2095-8676.2021.03.017
  Introduction  The DCS system of two 700 MW units adopting "constant-sliding-constant" variable pressure operation mode in Zhuhai Power Plant adopts DIASYS Netmation distributed control system, which is provided by Mitsubishi company of Japan. At present, when the units are running in the AGC mode, the load changing rate is on the low side, with the poor performance of load precision control and the frequency modulation response, while the pressure and temperature of main steam, reheater steam temperature and other main parameters fluctuate greatly with bad quality of adjustment, which does no good to the long-term safe and stable operation of the units.  Method  Through modeling of the way of control combined with experimental data, the direction of system designing was determined. Based on the basic frame construction of "Advanced Control" real time optimized control software pack, plans for primary frequency control, unit Coordinated Control System(CCS), main steam temperature, reheater temperature control and new AGC control on the basis of advanced control technology were designed in a targeted manner. Besides, with the tests of simulation system, the initial parameters of every circuit were determined.  Result  After the implementation of the project, the plug-in advanced control system of frequency modulation auxiliary service and the main frame DCS system realize undisturbed switching, and the comprehensive frequency modulation performance is significantly improved.  Conclusion  The comprehensive frequency modulation performance of AGC of the units is greatly improved and the expected target is achieved while the units adopted the plug-in advanced control system using optimized control strategy. Meanwhile, the actual load rate and the precision and response speed of frequency modulation is improved, and the comprehensive frequency modulation performance is obviously enhanced, which lays a solid foundation for the units to participate in the frequency modulation market competition.
Power System Technology
Research on Low Voltage Ride Through Technology of DFIG Based on Deep Neural Networks
Xinmei YU, Haojun CHEN, Xinghua WANG
2021, 8(3): 122-130. doi: 10.16516/j.gedi.issn2095-8676.2021.03.018
  Introduction  During the power grid fault, the low voltage ride through (LVRT) performance of the doubly-fed induction generator (DFIG) depends on the control parameters. At present, the optimization of control parameters is basically in the offline mode, which lies in the fact that it's hard for algorithm optimization to meet real-time control's requirement of the calculation speed.  Method  Therefore, the real-time optimization control method of LVRT following“offline training, online computation” was presented based on the principles of deep neural networks (DNN). Firstly, the appropriate LVRT strategy for optimization control was proposed for different fault severity levels. The parameters were clustered and optimized according to the respective objectives of each strategy, then the parameter list was formed.  Result  At the moment of power grid fault, the input parameters can be directly input into the trained DNN networks to quickly realize the optimization of control scheme and optimal parameters.  Conclusion  The joint simulation results based on PSCAD and MATLAB demonstrate the advantages of the proposed idea in optimization effect and optimization speed and the practicability is also illustrated.