Structural analysis is prerequisite to evaluate dynamic failures of vertical axis wind turbine systems(VAWTS). Several key scientific issues of structural analysis for VAWTS are reviewed in the present paper including aerodynamic models, wind and wave coupling, wind turbine foundations and structural analysis etc. The knowledge and development of structural analysis of VAWTS is discussed based on its historical developments and logical relations, and several typical models which have been developed in recent years are systematically summarized. The development trends of structural analysis for VAWTS are suggested on the basis of our understanding of essential physical mechanism of VAWTS.
The key functions and advantage of Rural Intelligent Distribution Transformer Terminal are introduced, and a design scheme is presented based on OMAPL138 dualcore microprocessor. Data acquisition, signal processing and realtime control are realized by digital signal processer (DSP) core, while humanmachine interaction, data storage, communication and security protection are processed by advanced reduced instruction set computer machines (ARM) core through embedded Linux. Tasks are distributed clearly between DSP and ARM, and data exchange as well as resource sharing can be easily implemented within the chip. The design of terminal is based on bus interface and modular technology, which enhances its expansibility and flexibility. Hotplug of daughter boards and convenient system upgrade are supported by the terminal.
The UHVDC transmission line between Hami and Zhengzhou needs the same corridor with other twocircuit UHVDC transmission lines. In the threecircuit UHVDC transmission lines with the same corridor, total electric field strength in the ground, the radio interference and audible noise are analyzed. In addition, the width of transmission line corridor and demolition range are obtained under the electromagnetic environment requirements, providing references for the design and maintenance practice of overhead lines.
Based on the actual operating data of wind power in Fujian, the probability distribution, correlation and chronological characteristics of wind power are studied. In addition, the effects of wind power on the synthesis load, power balance and peak load regulation of Fujian power grid in 2015 are discussed. It is found according to the practical output characteristics that the wind power has little effect on the annual maximum load, that is on the total capacity requirement of Fujian power system from the power balance point of view. However, it should be pointed out that more capacity requirement for peak load regulation will be brought about with the increase of the wind power and peakvalley difference of synthesis load.
The configurations of nonelectrical protection for converter transformer and smoothing reactor are introduced. The DC blocking accidents occuring in recent years due to nonelectrical protection for converter transformer and smoothing reactor are presented. The reasons are analyzed and the improvement measures proposed for further enhancing the reliability of the HVDC transmission system.
For the safety and stability of the 500 kV transmission line, SSZT1 angle tower which is widely used in the transmission project has been chosen for the prototype model test. In No.7 and No.18 load cases, bending occurs showing force differences between the real structure and the computational model. Aiming at the problems, the reasons for bending and solutions are introduced which could also be used as references for other tower design and tests.
Based on the analysis of the engineering geological conditions in Qinghai Province, the application feasibility and key technology of micropiles for transmission tower are studied. It is shown that soft ground is mainly located in alkaline land with a strong salt corrosion, and there are not good corrosion protection measures for micropiles foundation, so micropiles foundation is not suitable in soft ground. However, micropiles foundation have many economic and environmental benefits in loess ground. Therefore, the type and key technology of micropiles foundation in loess ground are analyzed, and the economy of micropiles foundation in loess ground is evaluated by example calculation.
Aiming at the increasingly significant problem of various natural disasters affecting power grid, a natural disaster risk assessment method for power grid is given in this paper. Combining the qualitative and quantitative analysis, improved analytic hierarchy process(AHP) is used to construct the hierarchical structure model of risk assessment, the weights of factors are calculated and then the degree of risk is determined. An example application shows the effectiveness of the assessment results. It will boost the power grid's capability to withstand natural disaster.
Dynamic compaction method is widely used nowadays in foundation treatment and subsequently, the environment hazards caused by dynamic compaction are receiving more and more attentions from engineering applications and the relevant departments. The monitoring experiments are conducted for studying the effect of the dynamic compaction on the environment in transformer substation of Guangzhou Huadu airport. It is considered of the effect of the construction conditions, the type of the hammer, and the weight of the hammer, the height of the tamping and the frequency of the tamping on the propagation of vibration. In addition, the effects of the vibration isolation trench are analyzed, and a safety distance is determined from the experiment.
In order to improve the precision of the load forecasting, some related factors are chosen in the process of establishing a load forecasting model. However, some factors that are not very important are taken into consideration, which increases the difficulty of establishing a load forecasting model. Even sometimes it is difficult to explain the model established. In order to avoid this kind of situation, the RE(ridge estimate) method is firstly used to select the independent variable set, and to exclude those factors which are not significant. Then, the PLSR(partial least squares regression) method is applied to establish the model based on the rest of the independent variables set. Through the practical example, it is shown that the method proposed in this paper is correct and effective.
Aiming at the meteorological features in parts of Xinjiang, a newtype indirect air cooling system with parallelizing configuration is proposed to 2×300 MW cogeneration plant. By the comparative analysis of technology and economy for 4 alternative air cooling systems, the economy of the newtype system is prominent, which adapts to the disadvantageous environment factors, such as high temperature in summer, chilliness in winter as well as strong wind, especially to the cogeneration plant under such meteorological conditions.
对南瑞继保RCS 985/S型发电机定子接地保护原理进行了分析。南瑞继保RCS985/S型发电机定子接地保护采用发电机机端零序电流、接地变压器二次侧电流以及发电机零序电压构造零序方向元件，以基波零序电压作为动作判据，能够准确判断发电机区内、区外单相接地故障，分析了该保护在长洲水利枢纽工程应用中的可行性。介绍了该保护在长洲水利枢纽工程中的应用并提出了使用范围，为南瑞继保RCS985/S型发电机定子接地保护选型提供了依据。
In order to reduce auxiliary power consumption and improve the unit efficiency, a scheme is proposed and analyzed that the steam turbine is used to drive the induced draft fan (IDF).Based on the phase3 Beilun Power Plant, the technology and economy and some conclusions are achieved, which can provide a reference for relevant engineering design.
The effects of ash on the abrasion and blocking of DeNitration Catalysts are introduced in coalfired power plant. It is shown that the ash abrasion on the catalyst is powerful based on analyzing the ash characteristics. In order to get rid of the coarse ash particle, reduce the abrasion and blocking on the catalyst, and prolong the catalyst service life, it is proposed to install the ash hopper and enlarge the flue section before SCR(selective catalytic reduction).
Automatic generation control(AGC) technology is used for remote controlling in electric network management. It is considered as an important method to guarantee the balance of electric network. In this paper, the problem of AGC technology based on mixburning coal slurry is analyzed. The corresponding countermeasure is proposed, such as strengthening the coal slurry mixing, improving the drying process, increasing the threshold of main stream pressure, simplifying the runup/rundown signal and the atresia signal, adjusting the control parameter and so on.
It is well known that the limestone preparation system, which directly influences the desulphurization efficiency and the control of SO2 content in the flue dust, is one of the most important assistance system of CFB(circulating fluidized bed) unit. Generally the system includes twostage crusher and mechanical screening system, which doesn't run well in the actual operation. In addition, the capacity of the limestone powder needed is much more than the designed output of the system. Therefore, based on the limestone preparation system of Baima demonstration power plant, the limestone preparation system suitable for largescale CFB power units is designed.
During the operation of units in some thermal power plant, the crack occurs of two bellows expansion joints of internal and external pressure balance in the heating network. The causes are analyzed and the solutions proposed, providing references for rational distribution, installation and fabrication of bellows expansion joints in heating network.
According to the requirements for the low voltage ride through(LVRT) in the standard of State Grid Corporation for uninterrupted operation of wind turbine unit, the effects of asymmetrical grid fault on the double-fed wind turbine unit are analyzed, and a mathematical model for the doublefed induction generator is established. Based on the mathematical model, the through plan by combing the rotor Crowbar circuit and DC Chopper circuit is designed and the corresponding control strategies are analyzed. Finally, the correctness and the feasibility of the circuit are verified.
As the typical series from of multiterminal DC(MTDC) transmission technology, cascade multiterminal UHVDC (CMTUHVDC) power transmission technology has good prospects for development. Base on the typical connection mode and configuration consideration of CMTUHVDC and according to the life cycle theory, the economic influence factors of CMTUHVDC and Twoterminal UHVDC selection are quantitatively analyzed, providing reference for CMTUHVDC selection.
The excellent thermo performance of the cooling tower is considered as the precondition for efficient, safe and full-load operation of the turbine. In this paper, the cooling performance due to the effect of natural wind is discussed.The benefit originates from the integration technology between air inlet diversion and frost proofing is analyzed combining with a real case. It is found that the integration technology effectively improves the thermo performance of the cooling tower, the economical performance of the unit and the reduction of pollutant emissions.
In the reconstruction project for a power plant in Minsk of Belarus, the operational risk is analyzed on the aspects of construction organization, process, technologies, staff and external environmental factors. In addition, the key issues and difficulties in the implementation of overseas EPC(engineer procure construct) projects are discussed in order to give a warning to other overseas EPC projects of power industry, so that the corresponding measures could be developed and the risks prevented.
The performance of wind farm units involved in the power grid has become a major factor for safe and stable operation of power grid. In this paper, the testing and analysis for the performance of Gansu Hexi wind farm units involved in the power grid are introduced. Based on test results, the performance of wind turbine and reactive power compensation device performance in wind farm are analyzed and evaluated, for improving which the suggestions are proposed.
In this paper, common quality defects during factory preparation of the four major pipes in ultrasupercritical thermal power units are summarized and analyzed, such as surface quality, offdimension, hardness abnormal and metallographic structure abnormal, weld defects and so on. Then the corresponding quality control measures and suggestions are put forward, providing references for further improving the processing quality of the four major pipes.
The construction of mass concrete for crossing tower pile foundation in 500 kV quadricircuit Xijiang large crossing transmission line project is considered. Based on the thermal calculation of mass concrete crack control during the construction stage, some technical measures are formulated including the optimization of concrete mixture, concrete temperature control, concrete layered pouring, and integrated conservation of internal distribution and external store etc, so that the construction is effectively guided, the harmful mass concrete cracks successfully avoided, and good effects received.
The platform of 1000kV series compensation equipment is much larger than the one of 500kV on area, weight and installation height. The traditional hoisting technology is limit by construction site, and the The platform of 1 000 kV series compensation equipment is much larger than that of 500 kV on area, weight and installation height. The traditional hoisting technology is limited by construction site, and a new special hoisting equipment is designed for lifting the platform of UHV series compensation equipment, i.e. a hoisting equipment with 4 pillars. The design function is firstly analyzed for the new equipment, and the equipment composition and function realization are finished accordingly. At last, the installation, commissioning and operation are analyzed for the new hoisting equipment in detail, from the view of field working.
The ultrasupercritical 1 000 MW units of Dongfang Turbine Co., Ltd. which have been put into production, are found to have the partial steam leakage problem in high pressure casing split. Based upon the past experiment, this paper develops some targeted construction measures, including proper handling the clearance of casing split and radial clearance of vapor lock, adjusting the clearance of the paw rest pin, adopting reliable sealing grease and thermal tightening of bolts, and so on. These measures work fine during installation process and avoid the steam leakage successfully.
