With the rapid development of wind power in China during the eleventh five-year plan, utilities face many problems and challenges occurring in wind farms and power grids. It is necessary to pay attention to efficiently develop wind power and successfully make five changes. Therefore, the sustainable and effective ways to develop wind power are proposed in this paper from scientific planning, standard design and orderly construction points of view.
In this paper, the development direction of coal-fired thermal power generation technology based on the energy structure in China is analyzed. Though carbon capture and storage (CCS) technology can nearly reach to zero emission of CO2, it is not the most economical way at present and still under research and development, requiring a rather long period for extensive use in coal-fired power plants. Therefore, there are many reasonable, economical and reliable ways for further reducing CO2 emissions in coal fired power plants, including greatly developing the supercritical/ultra-supercritical units, enhancing the thermal efficiency by technology innovation, improving the net efficiency of present ultra-supercritical (USC) units with 600 ℃ steam parameters, and developing advanced double-reheat units for reaching to higher than 53% of net efficiency in 1 000~1 500 MW USC units.
Field direct shearing tests on Gobi gavel soil are carried out in Xinjiang and Gansu province, where the shear characteristics and strength parameters are discussed. It is indicated that the Gobi gravel soil is of great shear capacity, of which the shear process under normal stress could be described as three stages including elastic deformation, elastic-plastic deformation to peak strength and strength demineralization to residual strength. The mean value, standard deviation and coefficient of variability for the internal friction angle of Gobi gravel soil are 40.6°~43.6°, 3.4°~10.3°and 0.003~0.253, while those for cohesive strength are 10.5~23.0 kPa, 1.2~7.3 kPa and 0.12~0.33 respectively. Moreover, the standard deviation and coefficient of variability for cohesive strength increase with increasing mean value. The results obtained in this paper can provide references for engineering application and optimized design in Gobi areas.
The power loss of ground wire, produced by the magnetic coupling between phase line and ground wire, is becoming a more and more important parameter for economical operation of the power network. There are a variety of measures to reduce the power loss, such as graded insulation and ground wire transposition. An example of UHV transmission line is presented in this paper to investigate the characteristics of induced electromotive force of ground wire and power loss under different phase sequences and conductor transposition modes. It is pointed out that the power loss can be reduced to a minimum by negative phase sequence and reverse transposition of conductor, as well as graded insulation and transposition of ground wire.
According to control indexes for DC transmission line, such as the composite electric field under the wires, ion current density of the ground, field intensity induced by radio interference and corona audible noise et al, the corresponding calculations are carried out for various bundle conductors of DC transmission line in 3 000~5 300 m ultra-high altitude regions. It is concluded that 4×LGJ-400/35 aluminium conductor steel reinforced (ACSR) is applicable for ±400 kV DC transmission line in ultra-high altitude region.
The finite element models of valve hall structure in ±800 kV convertor station is constructed in the paper. The model analyses of shot-pier shear wall structure and shear wall structure of valve hall are performed. The corresponding frequency and mode of vibration are analyzed, and the torsion deformation is discussed under earthquake wave. In addition, the dynamical and time history analyses of two valve halls are carried out, and the global assessment for torsion deformation discussed.
According to the relevant technical standards and technical solutions, combined with years of experience in project implementation, a design solution for state monitoring system of transformation equipment is proposed in this paper. Based on the production management information system(PMS), a unified state monitoring system of transformation equipment is established of “two-level deployments, three-grade applications”. As a result, the data processing, access and control of state monitoring device of transformation equipment are standardized, and the functions for status information display, warning, analysis, diagnosis, evaluation and forecasting of transformation equipment provided, achieving real-time monitoring of significant transformation equipment status and critical operating environmental information.
At present, it is required that the polarity distance of ±800 kV UHV DC transmission lines constructed or constructing is not less than 22 m in our country. In this paper, the possibility of decreasing the polarity distance is discussed by considering electromagnetic environment, length of the composite insulator string, air gap, angle of the V style insulator string and so on. In addition, the economic benefits are analyzed. The results obtained provide references for the design of future UHVDC transmission line.
In order to improve the accuracy of classification problem in intrusion detection for state grid, a novel intrusion detection model, which is based on the hybrid classifier, is proposed in this paper. The hybrid classifier is composed by kernel principal component analysis (KPCA), back propagation neural network (BPNN) and quantum genetic algorithm (QGA). In the hybrid classifier, KPCA is used to reduce dimensions of data. The classification model is trained by BPNN, of which the parameters are optimized by QGA. Based on the classification model, the data samples are classified by accurate intrusion detection. Compared with the traditional methods, the intrusion detection model based on hybrid classifier has better performance in reducing the calculation errors.
The 35 kV smart substation, the last link of smart substation, is widely distributed with large number of construction projects, of which the economic operation is very important except for smart, reliable, safe and high efficient operation. However, there is still no design specifications and construction modes for the construction of the smart substation with this voltage level at present. Therefore, a integrated construction mode is presented for 35 kV smart substation, and different construction modes of the smart substation are compared from all aspects.
When the power is transmitted from large hydropower station or thermal power plant located far away from the main power grids in HVDC project, the AC power system at sending end forms an island system. In Yunnan-Guangdong UHVDC transmission project, the DC frequency control function in island operation mode is simulated and analyzed by real-time digital simulator and the control&protection system of SIMATIC TDC. In addition, the shortcomings of the frequency control functions found in the simulation are analyzed, and the practicable improving measures are given. It is proved by the simulation that the improved measures are effective.
For the flue gas desulfurization(FGD) of circulating fluidized bed(CFB), the integrative process of desulfurization and dust extraction has many advantages of simple system, low cost, low maintenance cost, and high desulfurization efficiency ect. By the test analysis of the operation problems of CFB-FGD in the power plant, the causes and corresponding measures are put forward, providing references for design and operation of CFB-FGD system.
Focusing on the saturated soft soil foundation in electric power plant, the dynamic compaction and dynamic replacement method are adopted. The design and execution process are introduced in detail. The reinforcing effects are comprehensively evaluated based on the results of plate loading test, super-heavy dynamic penetration test and density test. In addition, the applicable conditions for the dynamic compaction and dynamic replacement method are presented, that should be helpful to the design of similar projects.
The voltage grade of main Xian power grid is 330/110 kV. In the initial development stage of power grid, the 300 MW grade generation units are all required to interconnect to 330 kV power grid. However, with the development of the urban load and power grid, the connection principle is not adaptive to the development of power grid completely. Therefore, taking the connection to power system of 2×350 MW generation units in Xian west suburb thermal power plant as an example, the feasibility, rationality and essential technology conditions are analyzed for the 300 MW grade generation unit connecting to 110 kV power grid by the sub-layer and sub-area way.
The control of main steam temperature is of difficulty in thermal power plant. Considering the effect of heat quantity of flue gas, the nonlinear characteristics of spray water valve and the reasonable range of temperature setting point, the main steam temperature control system is optimized by adaptive disturbance and predictive control technology of NO.5 300 MW unit in Zhejiang Zheneng Wenzhou Power Plant. The fluctuation range of main steam temperature is reduced effectively, and the control system can work well even the load under 190 MW. It is proved from the application that the technology is of high marketing value for generalization.
Based on reliability-centered maintenance(RCM)Ⅱ theory, the reliability maintenance analysis for electro-hydraulic(EH) oil system of supercritical steam turbine is carried out, several preventive optimization measures are proposed, and the original maintenance decision model of EH oil system is optimized.
In order to construct united planning system of SGCC, the overall framework of united power grid planning and design application is proposed in this paper, of which the main principles are determined with unity, standardization and openness. The corresponding function localization and operation mode are analyzed. The power grid planning & design application can provide data, function and professional work supports, for which the data management and interactive mode are primarily designed, achieving integration of technological process and management process and connection with other applications of five united system.
Along with the development of the Jiuquan 10 GW Wind Power Base, more and more problems appear from the influence of the large-scale wind power gird integration on the operation of grid system. After February 24th 2011, several grid dropout accidents happened, which show the big security and stability influence on the power grid system. In this paper, the Jiuquan wind power base is taken as an example to analyze the problem from wind power grid integration. The problems from peak load regulating, transmission capability, electricity consumption, AGC(automatic generation control), AVC (automatic voltage control)and frequency stability are focused. Relevant measures and suggestions are proposed at the end of the paper.
With the increasing applications of electrical and electronic equipments, there are more and more power quality problems due to the special loads, such as nonlinear, impact loads etc. Therefore, it is of great significance to establish an effective power quality management system for the special loads to ensure power quality of power grid. Based on this, the power quality management for special loads is discussed. It is found that the key elements during the management should include two factors, the management rules and the management procedure. In addtion, three core parts of monitoring, assessment and control of power quality are discussed and analyzed. The results can provide references for power supply companies to make power quality management regulations of special loads.
Before the constructions of overhead transmission lines, the conductor, the corresponding strain clamp and connecting fittings should be crimped by the steel mold. Three test specimens is made, of which the holding force is no less than 95% of the calculated tensile strength of the conductor. According to the failure of conductor crimping in the practical operation, the influencing factors are analyzed, the typical operating modes and causes summarized.
Aeolian vibration of overhead ground wire is very strong in Hexi 750 kV transmission line of Gansu province, resulting in slip of dampers, fatigue break of ground wire endangering the safe operation of transmission lines. Based on this, special dampers with preformed clamps is developed and collocated according to parameters of lines, terrain and weather conditions. For the particular areas with strong aeolian vibration, the anti-vibration device by combining damper with preformed clamps and damping wire is recommended. The new type of damper meet the standard requirements, is verified to work well by the indoor simulation experiments and field tests. The dampers have been successfully applied in Hexi 750 kV transmission line.
The installation of steel frame is a kind of highly dangerous work, requiring high-quality construction. In the first stage project of Haiphong coal-fired power plant of Vietnamese, the steel frame on the roof of the coal bunker is installed by the assembly technology at high altitude. In this paper, the establishment of supporting platform, installation technique of steel frame and key points prevention of quality are summarized, providing references for similar projects.
In the design of domestic transmission high tower, the T-type welded structure of flange with bolt holes on the inner and outer circle and self-made large diameter steel pipe is first applied to two 370 m high towers of 220 kV Zhoushan and mainland power grid connecting project. However, the largest diameter for flange is up to 2.33 m, and for steel pipe up to 2 m. The traditional welding method for flange and steel pipe can not ensure the deformation precision of weld. Therefore, in view of the features of high tower, a new welding process of fine wire mixing gas shield is innovated and adopted, which includes setting reasonable groove angle, making welding sequence, providing measures to resist deformation etc. The results obtained in this paper will provide technical basis for welded structure design and application of large diameter steel pipe and flange in high towers.
