The randomness and volatility of wind power bring difficulties for power system dispatching and operation. Taking Jiuquan wind power base the first million kilowatt wind power base in China as an example, the ultra-short-term wind power prediction method based on neural network was studied, which analyzes and processes the real-time data of wind speed and wind power. On this basis, the modeling process of ultra-short-term prediction was analyzed based on the neural network algorithm and Bayes rule. Finally, the prediction model was validated through prediction results. The results show that the prediction model is reasonable, and has a high prediction accuracy, which can also provide a reference for dispatchers.
Under the management of power grid enterprise, there are a large number of transmission lines and substations, which are located at different places. Some of those are located at barren mountain, plateau, depression, forest and other sparsely populated and complex environment, and are often threatened by kinds of geological disasters (such as debris flow, flood etc.), natural corrosion and aging. At present, the operation and maintenance of the facilities mainly depend on manpower, and lack effective methods of intelligent monitoring. Moreover, rush repair and rescue cannot be implemented effectively after problems occurring due to bad communication environment. In view of the actual need of transmission and transformation facilities maintenance, a satellite-based internet of things was built by using the functions (such as positioning, data transmission, etc) of Beidou satellite with independent intellectual property rights in China, which could realize the real-time monitoring, operation and maintenance management, safety guarantee, emergency rescue and other works for field transmission and transformation facilities, thus to achieve the cost reduction of operation and maintenance, to find risk in time, and to ensure the safety of power grid and personnel. The research can provide some useful references for the application of satellite-based internet of things in transmission and transformation facilities management.
Sola/coal hybrid power plant integrates solar energy and conventional coal-fired power plant to achieve the scale, industrial application of solar energy. The system reduces the investment of steam turbine and generator, which are necessary in traditional solar thermal power plants, so it has characteristics of lower cost and steady load. Solar energy can act as supplement energy to the thermal system of conventional coal-fired power plant, which can also avoid the unstable and unsafe operation of solar thermal power plant caused by frequently starting and stopping, by relying on the strong heat source of thermal system. Based on the analysis model of the established sola/coal hybrid demonstration power plant, the operation mode of solar field and thermal storage in the demonstration power plant were studied under typical climate and designed condition, as well as the flow distribution characteristics of regulating valve group were quantitatively analyzed, whose results could provide references for real operation rules and optimization in the future.
As an important part of smart grid, smart substation is the basic operation and control nodes of power grid. The accuracy and real-time of information collection in substation directly affect the safety and effectiveness of the overall operation and controlof smart grid. Aimed to the requirements of regulation and control integration mode in substation, some specific functions that smart substation should realize were proposed. Through the analysis of the status of information flow, the optimization scheme for transmission structure of information flow in smart substation was discussed, which could reflect the design principle of the close integration of information and centralized functions. In addition, the technical support system of smart substation was researched, mainly covering the panoramic data center, the public service, the basic application of the platform and security management, so as to present a building scheme for integrated information platform.
With strengthening of power grid, the short-circuit current has gradually become the factor restricting the development of power grid. Therefore, the effective solutions of short circuit become the priority during the development of regional power grid. At present, the western power grid in Tianjin is in operation with electromagnetic loop network. However, with the development of the power grid, especially the commissioning of 500 kV Xijiao substation, short-circuit problem of the 220 kV western power grid in Tianjin is becoming more and more prominent. The most effective measure to solve such issue is to decouple the 220 kV electromagnetic loop of the power grid. Based on the operation of Xijiao substation, two decoupling loop schemes were proposed for the 220 kV western power grid in Tianjin, one of which was recommended with detailed calculations and analysis of power flow, short-circuit current as well as transient stability of the power grid. Furthermore, suggestions for the future development of western power grid in Tianjin were provided.
The scientifical and reasonable partition for the level of icing zones along power transmission lines plays a key role for the safe and stable operation of power grid. Based on the analysis of the status of icing distribution map along transmission lines at home and abroad, the related techniques were discussed, including the measurement methods for icing, the numerical simulation of icing thickness, the mathematics statistical model, the partition standards, the treatment of microtopography and microclimate, the adjustment for operation experience, as well as the drawing technique of icing distribution map. According to the existing problems of the icing distribution map drawing and the construction planning of power grid, the development trend of the key drawing techniques of icing distribution map were proposed.
Icing problem of power transmission line has been existed for a long time. It has become more serious along with the global climate warming and frequent extreme weather, which will be a great challenge to the safe and stable operation of China's power grid. The types and formation mechanism of icing in transmission lines were analyzed in detail, as well as the influence of micro meteorological on the formation of icing and the security of line. On this basis, the monitoring technology of icing for transmission line, the pre-warning technology of icing, the hydrophobic coatings of anti-icing, the mechanical deicing technology, the melting ice technology for AC, DC and the passive deicing theories were analyzed in-depth. Finally, this paper introduced the new technology, new measures, new achievements and new trends for dealing with icing for transmission line, as well as the problems need to be solved urgently.
The numerical simulation study on the composite insulator and grading ring surface electric field distribution in UHV AC power transmission line has the characteristics of the various mediums, the complicated structure and the large amount of calculation. In order to assure the calculation accuracy, related influencial factors should be comprehensively analyzed to reasonably simplify the calculation model and enhance computational efficiency. A whole and a simplified 3D finite element model of double composite insulator in UHV AC transmission line was built. The influences of conductors, towers, hardware fittings, yoke plate on the composite insulator and grading ring surface electric field distribution were studied. Finally, the reasonability of the simplified model was validated. The comparison results between whole model and simplified model show that the simplification of tower is reasonable, and the simplification method that omits the hardware fittings and yoke plate is feasible, with controlling three-phase bundled conductors within a certain length. The simplified model can replace the whole model to analyze the electric field and potential distribution of the composite insulator and the electric field distribution on the grading ring surface, and it can reduce the calculation scale, as well as improve the analysis efficiency of parameters optimization for the insulators string and grading ring in UHV AC transmission lines.
In order to explore the multi-infeed DC modeling method in real time digital simulator (RTDS) platform, an equivalent system model like China Southern Power Grid was built including ±800 kV UHV DC transmission grid, based on the equivalent data of BPA with high load level case of China Southern Power Grid (CSG) in 2012. The hardware configuration and function of the experimental simulation platform were introduced, of which the basic steps of RTDS system modeling were presented, as well as the selection principle of element model in power system were introduced. The validity of generator control system models was proved by the dynamic response curve of generator in short circuit experiment of single machine-infinity bus power system. On this basis, through the comparison with each state variable during BPA steady-state operation, and the simulation results of typical AC faults and DC faults, the effectiveness and correctness of the proposed simulation models for power grid were verified. Finally, the error reasons of RTDS and BPA were analyzed in detail, as well as the superiority-inferiority of these two simulation softwares in simulation calculation was compared.
In order to accurately evaluate the power supply capacity of power distribution network, firstly, the tie-line matrix of main transformer has been established to analyze the upper limit of load rate of each tie-line unit according to the N-1 guideline. The identified load rates of main transformers were used to adjust those of other transformers, and the maximum load matrix without constraints was obtained. Secondly, the transferred load constraint matrix was built based on the constraints of transformer overloading and tie-line capacity, the transferred load needed in each tie-line unit was checked to correctly evaluate the power supply capacity of distribution network. Finally the effectiveness and correctness of the model has been verified through the practical application.
In order to analyze the correlation between basic physical and chemical property indices of biomass fuels, and propose a simple and convenient prediction method of fuel's gross calorific value and elemental analysis indices for biomass power plants, the correlation among each index of woody biomass fuels by using the method of Pearson correlation analysis, such as gross calorific value, elemental analysis, industrial analysis. Based on the results of the correlation analysis, the multivariate linear regression models were built with calorific value and elemental analysis as dependent variables, while industrial analysis as independent variable. Finally, the prediction effects of the regression models were evaluated by the error analysis. The results show that within the applicable ranges of the variable values, the difference between the predicted values gained from the multiple linear regression models and the measured values is small, leading to the tiny prediction errors. Therefore, the prediction results of the multiple linear regression models can be utilized as references or basis to determine the gross calorific value and elemental analysis of wooden biomass fuel.
In order to study the influence of structure parameters and operating parameters of evaporator on the thermal economy of waste heat recovery in Organic Rankine Cycle (ORC) system, from the perspective of exergy recovery, combined with the thermo-economic theory, which considered the initial investment of equipment, the time-value of fund and the costs of the evaporator in whole life cycle, an thermo-economic evaluation model with the annual net profit CNPV as an important criterion, was established for the evaporator. Based on the model, an example was calculated and analyzed. It is found that the annual net income of ORC waste heat recovery project may be negative when the net recycling exergy of ORC system is positive, which shows that a single evaluation method considering net recycling exergy as the only indicator is not accurate for the evaporator. There is an optimum condition in ORC system, in which the max annual net profit value can be reached. The highest annual net profit value (about 14 650 yuan per year) can be achieved when the heat transfer area of the evaporator, the flow of organic working fluid and the mass flow ratio of flue gas and organic working fluid are 28 m2, 0.06 kg/s and 7.8, respectively. When the operational parameters deviate from the optimum condition, it will lead to the greatly decrease or even loss of the annual net profit of waste heat recovery project.
Taking the new project of Jiangxi Fuzhou Datang International Power Generation Co., Ltd. as background (installed capacity 2×1 000 MW ), the layout scheme of deaerator bay in front of boiler furnace (bidding scheme) was proposed, according to the condition of side bunker, the specific conditions and characteristics of the power plant. The proposed scheme was compared with traditional internal deaerator bay scheme, including the layout of main building, the civil engineering structures, the layout and investment of pipes and cables. The results show that the distance between boiler house and turbine house can be shortened, and the space and the dosage of four critical pipelines can be saved in the proposed scheme. In addition, the main auxiliary can be arranged on side of furnace without internal deaerator bay, which can further compress the span and longitudinal dimension of turbine house, as well as reduce the floor space and the initial investment.
Taking W-flame boiler in Yangcheng Power Plant as an example, the combustion tests were carried out with using different coals and different blending ratio of anthracite and bituminous coals. A series of indices were analyzed, which covered the stability of boiler combustion, the characteristics of boiler coking, the safety of coal pulverizing system, the combustible content in boiler fly ash, the unit consumption of coal pulverizing system, and the air pollutant emission situation of boiler. The results show that the blended coal combustion in W-flame boiler can enhance the stability and economy of boiler combustion, reduce the NOX emission of boiler. Through blending lean coal with relatively low volatile or controlling the ratio of bituminous coal below 30%, the safety operation of boiler without anti-coking transformation can be guaranteed. Aimed at the coking problem of boiler, the coking position and reasons were analyzed to propose technical measures of anti-coking, whose effect has been verified by the practical application.
The turbine of No.1 unit in Ningde CPR1000 PWR nuclear power plant (the capacity of 1000MW), is the first domestic half-speed turbine in China. The equipment features of half-speed turbine was analyzed, and some measures were proposed to control the vibration of the turbine from the aspect of installation, including the installation of second grounding embedded parts and sizing block, the parallelism adjustment of bearing bush, the adjustment of flow path clearance, the load distribution of HIP, the connection between LP and condenser, the spring release, the shafting alignment, the wheel diameter ream connection, and other processes. The actual operation of the unit shows that the improvement is obvious after the implementation of these measures, with which the maximum shaft vibration is 40.0 μm and the maximum vibration speed of bearing bush is 1.42 mm/s, both of the two indices can meet the standard requirements.
Taking the transformation of flue gas system in 600 MW unit of a power plant as an example, the feasibility of “combining two into one”retrofit for boiler induced draft fan and desulfurization booster fan were discussed from two aspects of economy and safety, the technical scheme of “combining two into one” retrofit for fan was proposed, including design principles, design parameters, the layout optimization and design pressure calculation of flue channel. The implementation of this technical scheme can reduce the flue gas system resistance and the engineering quantity of transformation, and then it can save the investment of transformation, improve the equipment energy efficiency, as well as the safety and reliability of unit, and finally can provide reference for similar transformation projects.
Conductor selection is critical in the design of UHVDC power transmission project, which should not only meet the requirements of electrical and mechanical performance of transmission lines, also should be economic. The technical economy of conductors with different cross-section (1 000 mm2 and 1 250 mm2) and multiple bundled in ±800 kV and ±1 100 kV DC transmission lines were compared and analyzed, based on the economic calculation method of total life cycle. The analysis results show that the conductor selection is strongly influenced by power loss hour and feed-in-tariff price, so the conductor selection should comprehensively consider all the factors to determine a reasonable conductor scheme.
In order to study the structural damage and mechanical property of Super304H steel in high temperature condition, two kinds of the Super304H heat-resistant steel were taken as research object: one was serviced at 863 K for 20 000 h as the reheater in an ultra-supercritical unit and the other was aged at 923 K for 1 100 h with the same P function value. The structure aging of the Super304H reheater was investigated after running for a long term, and the microstructure aging and mechanical properties degradation were studied on serviced and aging super304H steel tubes with same P function value. The results show that microstructures of the inner/outer side of the steel tube are heterogeneous due to their different running environments. The microstructure and mechanical properties of the inner side of the serviced Super304H steel tube are approximately equal to those of the aging super304H steel tube with the same P function value, however, the structural damage of the outer side of the serviced steel tube is more severe than that of aging one. Therefore, the artificial aging method in lab is conditionally accepted to simulate the structural damage of serviced steel tube, based on Larson-Miller parameter.
According to the new technology promotion, scientific & technological achievements transformation and resource sharing in State Grid Corporation of China, the working mechanism of science and technology innovation was discussed, overall framework design and detailed functional design of science & technology resource sharing platform were proposed for State Grid Corporation of China, so as to form new technology promotion functional module with the core of catalogue architecture, achievements transformation functional module combined free market and valuation, and resource sharing functional module including 4 display units. The results show that the science & technology resource sharing platform has been applied in practical work of science and technology innovation in State Grid Corporation of China, which can effectively meet the business demand and has a significant promotion to the future work of science and technology.
Owing to the slowing down step of current macro economy, in the achievement assessment of enterprise performance by State-Owned Assets Supervision and Administration Commission (SASAC), the weights of asset-liability ratio and economic value added (EVA) are increasing, and the available investment quota of power supply company is further reduced. The strategic objective of power supplycompany is to pursue economic benefits under the premise of social responsibility realization. so the improvement of project evaluation method is very important for improving the investment rationality of power supply company. Taking Chongqing Power Supply Company as the research object, an improved utility comprehensive evaluation model is proposed, which establishes the evaluation index system from two aspects of strategic objectives and projects properties, based on specifying the strategic objectives theory by projects. The evaluation index system could comprehensively evaluate projects by using quantitative and qualitative analysis method, and could provide references for the decision-making of a group of projectsin the future. The comparative analysis on different projects shows that the model has good application value.
The fault location is unable to realize in the actual operation of transmission lines, due to the current transformer saturation, the distortion or unavailable current at one side of breaking line, and the incomplete synchronization of sampling data at both sides of lines. According to this situation, a new accurate, practical fault location method was proposed with only using the voltage of both sides and the current of other side, based on the pure resistance properties of transition resistance. The new method offers a better solution for the fault location errors caused by current transformer saturation or line breaking, in which the accuracy of fault location is independent of power angle and fault inception time. This method doesn't require the complete synchronization of sampling data of both sides, as well as has a small amount of calculation without false root problem, and high theoretical and practical value. The simulation results of ATP-EMTP show that the proposed method is correct and has high accuracy.
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