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RSS2020 Vol. 7, No. 3
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2020, 7(3): 1-5.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.001
Abstract:
［Introduction］ The energy consumption of air conditioners is gradually increasing， which is one of the main reasons for the difference between the peak and valley power consumption of the power grid. Analyzing the characteristics of district cooling and cold storage technology and actively adjusting the distribution of electricity consumption of air conditioning and refrigeration systems to reduce the peak load of electricity consumption， provide references for planning， design， and operation of district cooling. Method Combining the literature review of cold storage engineering research and actual case analysis， we botained the characteristics of water storage and ice storage technology outside the coil， the nature of resources for district cooling and the principles to be followed. Result The results show that development of district cooling and cold storage technologies in China is promising. The water storage system is flexible and convenient， and it is advisable to use the electricity price mechanism to encourage users to invest themselves. As for the ice storage system outside the coil， the initial investment and total life cycle cost per unit of the cold storage system show a downward trend with the increase of the size of the cold storage system， but the change trend is gradually flattening. District cooling projects should be planned in advance. And it is regarded as a project that maximizes the benefit of resources of all members of the district. All members must participate to get the maximum benefit and share it with all members. Conclusion This work provides some guidance for further study on district cooling and cool storage technology.
2020, 7(3): 6-22.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.002
Abstract:
［Introduction］ China’s power grid is now entering the new era of smart grid with the “power-information-business” interconnected stage， where the cybersecurity in the information system and the operational security in the power system are closely coupled， which， however， would cause severe security problem of the cyber-physical system（CPS）. Method This paper surveyed on the cybersecurity issue of CPS and summarizes the corresponding risk estimation and management framework.Then the paper introduced the background and current status of cybersecurity， categorized the state-of-the-art methods， risk estimation framework， modeling insights， etc. This paper also fundamentally investigated both the advantages and disadvantages of each model and evaluated its development potentials. Result This study would help enterprises to screen and identify cybersecurity events and explore the correlation and dependency within the events， which may help researchers to exploit new interests. Conclusion This work induces investors to optimize their resources and budget allocations， which would also guide for security engineers to proceed with cyber risk estimates and to prepare contingency plans.
2020, 7(3): 23-27.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.003
Abstract:
［Introduction］ The primary issue of my country's data center industry is energy-saving assessment， that is， the issue of "energy evaluation". In recent years， the data center industry causes a lot of waste of investment due to the "energy evaluation" problem. At the same time， it severely restrictes the development of my country's data center industry. At the same time， it restricts the development of big data centers， artificial intelligence， industrial Internet and other fields in my country's "new infrastructure". Method This article combined the characteristics of the data center industry， through a systematic and comprehensive analysis of the energy-saving evaluation system， to find the key factors for the implementation of the system in the data center industry. The paper systematically elaborated the main concepts encountered in China's "energy evaluation"， that is， the energy conservation assessment of fixed asset investment projects. Result The author systematically explains the origin of energy consumption indicators， the definition of standard coal， the standard coal coefficient of power grid conversion， the meaning and difference of power equivalent value and equivalent value， the change of data center industry classification and the calculation method of data center industrial added value and the calculation method of power grid carbon emissions. From a macro perspective， the author systematically interprets the relationship between energy consumption indicators and data centers. Conclusion For participants in the data center industry， understanding these key factors and the relationship between these factors can help understand my country’s current and future "data center" related policies. It can important strategic guiding significance for promoting the development of the data center industry and then promoting the development of "new infrastructure".
2020, 7(3): 28-37.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.004
Abstract:
［Introduction］With the progress of digital economy， the "scale" and "hashrate" of data centers are constantly expanding， and the "energy consumption" and "operation cost" of data centers will also be constantly rising. In order to realize the effective utilization of waste heat in the data center and realize the linkage optimization of energy efficiency of the data center， this paper constructs a production-consumption type data center energy system based on CO2 heat pump. Method The system took the data center as the producer and consumer， consumed electricity for refrigeration and recycles the heat generation for residential heating. The energy system of production-consumption data center adopted three methods： direct air cooling， direct expansion of buried pipe cooling and terminal cooling of building heating to realize data center cooling. Natural cooling was utilized to the maximum extent to reduce power consumption of the system. Choosing the circulating working medium of the heat pump system for CO2 waste heat recovery can improve the compactness and environmental friendliness of the system. Result The system can effectively reduce the cooling load， and then reduce the refrigeration power consumption when the average occupancy rate is low. When the average occupancy rate is 0.6， the system can reduce the annual cooling load by 108 MWh， save 167 MWh of power consumption， provide heating for the building by 290 MWh， and obtain an annual income of 42，300 yuan. Conclusion The system can recycle waste heat of data center for building heating and realize effective utilization of waste heat of data center in off-heating period. The coordination between waste heat of data center and building heat load is realized by ground source heat pump system， which provides reference for energy efficiency linkage optimization of production-consumption data center.
2020, 7(3): 38-45.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.005
Abstract:
［Introduction］ In order to promote the coordination of generation and transmission in the electricity market， this paper proposes a coordinated generation and transmission planning method based on economic efficiency evaluation of power grid. Method With the gradual advancement of the power market reform， the competition of generation side was more diversified and the selling side was gradually liberalized. Traditional planning methods of power grid might no longer be applicable in the power market. In this paper， the main causes of the inconsistency between power supply and power grid development under the new environment of power market were analyzed from the aspects of uncertainty of power supply development and power flow. Result The cost-benefit method to Evaluate Economic Efficiency is applied. By calculating the net benefit of the system with or without the project， the benefit-cost ratio BCR of each project is finally obtained， which is used to optimize the power distribution and serve as an important basis for the decision-making of power grid projects. Conclusion It is suggested that the coordination between generation and transmission in power market can be promoted by optimizing and improving the method of power grid planning and establishing an evaluation system of power grid economic efficiency.
2020, 7(3): 46-54.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.006
Abstract:
［Introduction］ Based on the trend of consuming renewable energy sources （RES） through the market-based trading model， the “market electricity price + renewable energy certificate （REC） revenue” will become the main operation of energy generators in the future. Based on the research background of RES participating in spot power market， this paper studies the price of REC. Method Based on the optimized clearing model of the spot electric energy market， applying the theory of the life cycle costing （LCC） of RES generation and satisfying the internal rate of return （IRR） of the energy generators， we established the optimization model of coupling REC-electric energy market. Combined with the seasonal output characteristics of RES， the simulation and measurement methods of the seasonal curve and fluctuation interval of REC price are proposed. Result The price of REC for different types of RES are different， and the price of REC for different types of RES also has different climatic correlations. Conclusion Scientific and reasonable calculation of REC price can not only help RES generation enterprises make income assessment and more accurate investment decisions， but also provide relevant decision-making support for power market entities and trading centers.
2020, 7(3): 55-61.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.007
Abstract:
［Introduction］ As the guarantee for the stable of the power system， the marketization of the regulation auxiliary service has been put on the agenda. The energy-regulation joint optimization becomes a mode of market organization. This paper aims to study the combined optimization model of the electric energy-regulation market considering the performance difference of frequency modulation resources in the PJM market background. Method Regulation auxiliary service pricing adjustment model and the joint clearing model of electric energy and regulation market considering the difference of fast and slow regulation resources and regulation performance was proposed in this paper， which were applied to the simulation of a real power grid to compared with domestic electric energy - regulation step clearing market. Two typical scenarios were set up in wet season and dry season. The clearing of regulation resources， the influence on the electricity purchase cost in the spot market and the active degree of regulation market were studied in detail. Result In the stepwise clearing mode， the rapid regulation resource has obvious advantages and causes the increase of electricity purchase cost in the electricity market. In the electricity-regulation joint optimization model， the clearing results of fast and slow regulation resources are affected by the pricing adjustment strategy and the increase rate of electricity purchase costs in the power market is smaller than that in the stepwise model， and the clearing price and fluctuation degree in the regulation market are higher than that in the stepwise clearing mode model. Conclusion The combined optimization mode of electric-regulation modulation with reasonable price adjustment strategy is helpful to realize reasonable competition among units with different regulation performance and stimulate market vitality.
2020, 7(3): 62-69.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.008
Abstract:
［Introduction］ Intelligence of offshore wind farm is a realistic need to improve the operation level and benefit. Method Definition of Intelligent offshore wind farm was firstly proposed and then architecture of the intelligent offshore wind farm was established. The intelligence of offshore wind farm was formed vertically of four strata， such as intelligent device， service control， plant-grade control and group supervision. Construction means and detailed project practice advices were put forward， guiding the intelligence of offshore wind farm. Result The proposed intelligence method covered the entire life cycle of project， including the design， infrastructure and operation and realized intelligent monitoring and management of offshore wind farm equipments and assets. Conclusion The proposed method can improve the automation level， operation and maintenance efficiency of offshore wind farms， reduce operation and maintenance costs， and improve the ability of resisting risks.
2020, 7(3): 70-80.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.009
Abstract:
［Introduction］ The design waves of Nanhui， Donghai and Dafeng offshore wind farms in China are all in medium water depth and very close to the breaking limit of waves， it is necessary to explore the dynamic response of monopile type offshore wind turbine foundation under breaking wave load in shallow water. Method In this paper， FAST full-coupling analysis software was used to calculate the hydrodynamic load by considering the method of wave stretching， the coupling dynamic response characteristics of a monopile type OWT in the East China sea were analyzed. Result The analysis results show that the method of wave stretching is effective in calculating the breaking wave load， which is closer to the actual breaking force of the wind turbine. The first order natural frequency of the monopile is more easily excited by the breaking wave， and the dynamic response of the structure is more remarkable under the combined action of wind and waves. Conclusion The research results provide a certain reference for the development of monopile type offshore wind power in shallow water nonlinear wave region in China.
2020, 7(3): 81-88.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.010
Abstract:
［Introduction］ In order to obtain the safe burial depth of the submarine cable under the conditions of the sandy seabed and to ensure that the submarine cable is not threatened by the anchor， the safe burial depth of the anchor under the conditions of the sea sand seabed is given. Method In order to verify of the reasonableness and safety of the buried depth， based on the South China & Hainan power grid interconnection project I， the process of dragging anchor in sandy seabed was simulated， and the 3D finite element model of Hall’s anchor was established. The 3D sandy seabed numerical model based on Finite Element Method and Smooth Particle Hydrodynamics （FEM-SPH） was established. The process of dragging anchor was simulated and the drag curve of anchor in sandy seabed was obtained. The influence of mass of anchor， constitutive parameter and other factor to the penetration depth and drag force was analyzed. Result The simulation results show that the buried depth of the submarine cable should not be less than 0.35 m under the condition of sandy seabed with different soil quality. Conclusion Our results can provide theoretical basis and technical support for the design of submarine cable protection under sandy seabed conditions， and also can optimize the buried depth of submarine cables under sandy seabed conditions.
2020, 7(3): 89-94.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.011
Abstract:
［Introduction］ In view of the fatigue problem of support structure for offshore wind turbine， fatigue performance of transition piece with external stiffening ring was studied. Method Static and fatigue tests of A1/5 scale simplified support structure model were carried out to obtain their hot spot stress and fatigue life. Finite element analysis for the test model was conducted with different element type according to DNV rules. Fatigue damage obtained from experimental tests was compared with that calculated by numerical simulations. Result The results show that the main discrepancy between test results and specification methods is the selection of S-N curves. Conclusion Finally， on the basis of experimental data and DNV rules， two different methods for evaluating the fatigue damage of transition piece are given. This work provides some guidance for further application.
2020, 7(3): 95-101.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.012
Abstract:
［Introduction］ At present， power grid security and stability analysis practices adopted by Guangdong Power Grid can basically meet the needs of power system operations， but there are some shortcomings. It is impossible to clarify the impact of causes on security and stability of power system in a simple and effective way. Method This paper proposed the “with or without contrast” idea and studied the influence of various factors on system stability， and gave a pragmatic method based on this idea. Result This paper studies voltage instability of the Pearl River Delta power grid by adopting the new method proposed . The results show that both the transient characteristics of motor load and conventional HVDC have a significant impact on the stability of the system. In contrast， motor load have a more fundamental effect on system stability.The negative impact of conventional HVDC transient reactive power characteristics on system stability is apparent only in certain scenarios. Conclusion The case study shows that the method proposed in this paper can quickly and efficiently evaluate the influence of various factors on security and stability of the system， deepen our understanding of stability mechanisms of power grid， and can get conclusions that traditional methods can not draw. The ideas and methods proposed in this paper can provide useful reference for the industry to undertake similar researches.
2020, 7(3): 102-106.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.013
Abstract:
［Introduction］ The paper aims to find out whether the existing lines meet the requrements of new load code. And the ratio of design value of wind load between old codes and new code is discussed. Method In this paper， different load factors of different codes were given and the wind load design values of typical 500 kV and 220 kV lines were calculated and compared. Result The proportion of wind load design values calculated by different old codes to new load code were given. Conclusion Our data suggest that some of the existing lines designed by old codes not meet the requirements of new load， and have low reliability， they should be reforcement or reconstruction.
2020, 7(3): 107-111.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.014
Abstract:
［Introduction］ In view of the detection， circulation and detection data of large quantitie of transformers， it is impossible to record， over manage and display the whole process. Methods Based on the digital technology and management methods during test process， the overlay analysis of artificial intelligence， automatic recognition and new technology such as Internet +， detection， we put forward a set of digital integration test flat based on digital label sample transformer and its management system design to organic integration the data collection and processing of transformer analysis process. Results Finally， the transformer intelligent detection system based on RFID tag realizes the standard modular products in the framework， solves the problems of detection progress and sudden large-scale detection management in the process of transformer product detection， and realizes the information fusion and detection intelligence of transformer laboratory. The intelligent detection process of transformer and visual management of laboratory are realized. Conclusion The construction of the transformer digital intelligent integration test platform can improve the efficiency and accuracy of data processing， realize the centralized management of a large number of samples through Internet + fusion， promote the standardization of the construction of equipment integration test process， and put forward the idea of intelligent regional integration test management mode .
2020, 7(3): 112-118.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.015
Abstract:
［Introduction］ Aiming at the problem of orderly charging of electric vehicle photovoltaic charging stations， the paper aims to establish a bucketed order charging strategy. Method The structure and working principle of the electric vehicle photovoltaic charging station were studied， and the charging conditions of the electric vehicle and the state of charge of the energy storage battery were constructed. During the peak load period， while meeting the vehicle charging demand， reduces the power grid purchases and the cost of electricity purchase， assisted the power grid to “eliminate the peak”. During the low load period， while meeting the vehicle charging demand， increased grid purchases and assists the power grid to “fill the valley”. Result The validity of the model is verified by simulation examples， compared with instant charging solutions， shows the advantages of the builted model in reducing the cost of electricity purchase and reducing the peak-to-valley difference of the power grid. Conclusion The charging strategy of the proposed electric vehicle photovoltaic charging station is correct and effective， and can provide reference for practical applications.
2020, 7(3): 119-124.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.016
Abstract:
［Introduction］ The paper aims to study on the investment features of ±800 kV Converter Stations and provide guidance for the future constructions of ±800 kV Converter Stations in the field of project cost. Method By collecting data of design quantities，project budgets and project settlements of ±800 kV converter stations， we analyzed the costs of ±800kV converter stations by statistical analysis method and cost composition method. Result The construction cost and investment level of ±800 kV converter stations is given， and the trend of investment level is judged. Conclusion The cost of ±800 kV converter stations per MW is between 0.65~0.97 milion RMB， the componet ratio， arranged from high to low as： equipment procurement cost， other cost， construction cost and installation cost. Moreover， installation cost and other cost are relatively stable， equipment procurement cost is downward， and construction cost is rising. The overall investment level shows a downward trend.
2020, 7(3): 125-130.
doi: 10.16516/j.gedi.issn2095-8676.2020.03.017
Abstract:
［Introduction］ In the basic theory of digital signal processing， the calculus operation of continuous time variable function can be transformed into the difference and accumulation operation of corresponding discrete signal.At present， the application of this principle in microcomputer type relay protection is based on the software operation of fixed interval sampling value.In this paper， A new application type of the above theory is proposed， which integrates the sampling and operation process into the discrete， quantization and coding links of A/D conversion， so as to simplify the computational overhead and improve the protection performance. Methods The real-time sequence and delay sequence of VFC serial pulse signal were taken as variables， the counter was taken as the core computing hardware， and the single and multiple "floating operation Windows" were constructed with pulse delay devices to realize the hardware synchronization of calculus and phasor addition and subtraction.Based on the mature theory of software protection algorithm， the new algorithm formula is obtained by interval transformation and the loop construction mode is proposed. Result After discussion and calculation， the following results are obtained. The new method can be used to construct the instantaneous integral value of the electrical quantity， the instantaneous sampling value and the effective value of the definite integral. Conclusion Although the operation is based on the same basic principle as software operation， the physical process of operation is very simple， which can complete high-precision synchronous operation， and form a variety of operators， which can construct a protection scheme of multiple principles.
