By means of provision comparison and calculation, similarities and differences in ice load designed and its modification, wind load combined with icing, non-uniform ice load and wire broken conditions among different standards are analyzed. Results show that correction factor for conductor diameter in Chinese standards agrees with that of IEC standard, while the correction factor for conductor height is higher than that of IEC standard. As for the minimum wind speed rule, the wind speed combined with icing in Chinese standard agrees with that of IEC and CSA standards. Because of the differences in basic ice load and ice covering ratio, uneven ice load corresponding to a return period of 50 years in our standard agrees with that corresponding to a return period of 500 years in IEC standard, also reaches and is even higher than that in CSA standard corresponding to a return period of 150 years. The ice covering ratio of wire broken in our standard agrees with that in IEC and CSA standards corresponding to a return period of 500, 150 and 50 years respectively.
Air-cooling systems and water-cooling systems of steam turbine differ much in their ends of exhaust, as a result that the method of back pressure control for ordinary water-cooling systems is not applicable to air-cooling systems. Therefore, the safety margin of back-pressure control is provided, based on which the fuzzy control approach is proposed for applying in direct air-cooled units. The back pressure of air cooled steam condenser is easy to be influenced by the local environmental temperature and the fans speed, so that a mathematical model is developed based on the traditional air-cooled units with off-design characteristics. It is verified by the simulation that the approach to a large extent can ensure the air-cooling system operating under most cost-efficient and safest conditions.
Distribution reconfiguration and service restoration are the critical technologies for operation and control of distribution grid. In smart distribution grid, the technical challenges faced by the distribution reconfiguration and service restoration are analyzed, and six major technical requirements proposed where the research methods and research orientations are discussed, providing references for the similar research in the future.
Aiming at large-scale data collection points and intensive collecting characteristics of power users in our country, the demands on database of electric energy data acquire system are analyzed in the construction of smart grid. The construction plans of real time database in electric energy data acquire system are discussed from the system composition, technical architecture, database deployment, and the construction models etc. The program can ensure the reliability of data collection, enhance the agility of data applications, have universal data interface with plug and play, show the innovative application of data flow, and have the function of unique data nanny. The application of the construction plan is pre-research of implementing time-of-use(TOU) and makes the basis of guiding the social scientific and rational use of electricity.
Distribution generation(DG) of oilfield based on associated gas has the dispersive characteristics and is of small capacity, which is treated as PQ point in power flow calculation according to load control type. A distribution network reconfiguration algorithm based on simulated annealing and immune algorithm is proposed in this paper, where the annealing operator simulated by Boltzmann is used in selection operation, and the method of immune vaccine is applied for improving the diversity and convergence performance of population. In order to avoid the infeasible solutions in evolution, a method of public switches matrix of loops is proposed, and the searching space is compressed effectively. The tested system shows the advantages of given method, and great benefits can be obtained in oilfield application.
The source servicing in the smart substation offers the base for the model integration between the substation and the main substation. The IEC 61850 Ed.2 provides the base for conversion and share of the information model between the substation and the main substation. The description form, the structure, the function and the characteristics of the SSD(system specification description) model in IEC 61850 Ed.2 and the CIM(common information model) model in IEC 61970 are analyzed. In addition, the difference and characteristics between SSD model and CIM model are compared. As a result, the mapping relation and the common ground are obtained. Furthermore, the conversion technology between SSD model and CIM model is realized, which provides forceful guarantee for data consistency at dispatch centers in source servicing of unified information platform of smart substation, and for the information share between the substation and the main substation.
The controlled reactor has the advantages of simplifying the control of reactive power and reducing the active power loss of the grid. Taking the operation mode of Inner Mongolia power grid in 2011 into consideration, the configuration scheme for the application of controlled reactor to Inner Mongolia 500 kV power grid is discussed by power flow calculation software, for reducing the system loss on the premise of ensuring voltage passing rate. In addition, through the effect analysis of voltage modulation, economic analysis, and the simulation analysis of N-1 breaking, the feasibility of the configuration scheme is discussed. Furthermore, the conclusion of the application of controlled reactor to Inner Mongolia 500 kV power grid is drawn and some suggestions are provided.
For Jinan-Xuzhou part of 1 000 kV UHV Ximeng-Nanjing project, the transposition tower type is recommended of 1 000 kV UHV AC double-circuit transmission lines on same tower, by the analysis of technical and economic comparison, and by referring the research achievements and operating experience of domestic 750 kV and 500 kV double-circuit transmission lines on same tower. The research results in the paper can be applied to engineering design.
The economical span of UHVAC double-circuit transmission line has great significance to the optimization of tower design and the reduction of project total investment. The economical span of UHVAC double-circuit transmission line is calculated under ideal conditions. Furthermore, its sensitivity is analyzed from climate, terrain, conductor type, ground clearance and tower material et al. The tendency of economical span under various boundary conditions is discussed. The results may provide references for subsequent design of UHVAC double-circuit transmission line.
Conductor selection is an important link in designing large-crossing transmission project. In this paper, the characteristics of KTACSR/EST conductor and its application in large-crossing transmission projects are introduced. Taking a new-built large-crossing transmission project in Guangdong province as an example, the technical and economic comparison of different kinds of conductors are carried out. It is shown that the KTACSR/EST conductor can reduce the wind load of the tower and the investment of project effectively.
All-direction unequal legs transmission tower are widely applied on the transmission projects in mountainous areas while long time-consuming of composition calculation is always the greatest obstacle to accurate optimal analysis. An improved substructure method is introduced in the calculation prcocess of internal force due to comparability of different assembled models for unequal legs. The transmission tower is divided into two parts including the substructure and the leg stucture. The block decomposition algorithm is used in the calculation of equivalent stiffness matrix and load matrix. As a result, the DOF condensation and border nodal treatment are accomplished, so that the time is saved for most of composition and decomposition of DOF and the calculative efficiency enhanced. Furthermore, an idea is put forward for reducing the calculation capacity by combining with time consuming analysis.
Aiming at several optional connection modes of 20 kV for 110/20 kV and 220/20 kV substation, the technical and economic indexes are analyzed of reliability, flexibility, economy, adequacy and investment, as a result that the optimal selection is proposed for design, providing references for feasible selection of engineering connection.
In No.1 unit of Tongchuan power plant, the bus coupler breaker tripping accident occurs which is caused by memory over-current protection malfunction of generator after main transformer differential protection acts in B phase ground fault of HV side of main transformer. The principles of memory over-current protection of generator are analyzed in detail. In addition, the treatment of accidents is put forward including increase of generator interconnection and cancellation of bus coupler breaker tripping. Combining with the development of relay protection for large units, the backup protection of generator is discussed, for simplifying which the corresponding suggestions are provided.
According to problems occurring in the process design for the cross-flow natural draft cooling tower, the improvement measures are put forward including the key equipment structures, simulated calculation approach, freeze-proofing and reductions in noise et al. Furthermore, the technical and economic analysis is carried out for the application of large cross-flow cooling tower on the nuclear power station. It is concluded that the cross-flow cooling tower applied in the nuclear power plant is feasible, of which the advantage is particularly evident in the large nuclear unit.
The design of Datang International Linfen Cogeneration Power Plant in Shanxi is restricted by the construction sites. Therefore, an unique design plan is provided including the general arrangement, exhaust steam extraction of feedwater pump and turbine, dust extraction and machine layout of coal handling system, arrangement of water circulation pump house for auxiliary engine and et al, which ensures the design schedule and design quality, and is verified by the practical application.
Various steam seals have their own features, of which new types substituting for traditional ones has already become a trend. The structures and sealing mechanisms are introduced and the steam seals compared including serrate type, cellular type, lateral teeth type and Brighton steam seals. During the reconstruction of 2 unit in the State Power Generation Co., Ltd. Tongling, the lateral teeth type and cellular type steam seals are applied, and the actual operating conditions are analyzed. Furthermore, the influences of various types of steam seals on the safe and economic operation of steam turbine and energy saving are discussed. It is shown that the safety, tightness and economy are prominent by the reconstruction of steam seals.
Because of low temperature, deficient Oxygen and bad nature conditions at high elevations, it is difficult to construct for Qinghai-Xizang DC transmission project. In order to solve the low efficiency of the workers in the construction, the holding pole with modular mast section is developed, which has components of light weight and occupies little space in transportation, effectively reducing labor intensity in site handling, achieving convenient mechanical transport and improving construction safety.
At present, the manufacturing technology of domestic medium speed coal mill(MPCM) has different features by introducing, absorbing and reconstructing the overseas manufacturing technology for related series MPCM. The introducing processes for domestic HP, ZGM, MPS, MPS-HP-Ⅱ MPCM are introduced, and the corresponding structure and operation effect analyzed. Based on this, the structure beneficial to operation and maintenance of the mill is pointed out. Furthermore, an optimal structure by fusing the advantages of each MPCM is puts forward, providing references for the selection and development of domestic coal mill.
The traditional methods for power quality monitoring have the disadvantages of large amount of data processing, incomprehensive data collection, and unable to grasp the power quality indicators in real time. In this paper, the implementation of real-time and online monitoring the power quality is discussed, and a new type of power quality monitoring system is designed. The system with three-layer distributed structure integrates the subsystems with different monitoring objectives into a platform, improving extensible ability of the system and capabilities of power quality monitoring in large regional power system. It is shown from actual operation that the system can monitor power quality parameters accurately and reliably in real time, and is of good event handling function for transient power quality, greatly enhancing the capabilities of monitoring power quality by electric utilities.
Aiming at the transmission of receiving distribution system connected by multi-infeed voltage source coverter high voltage direct current (VSC-HVDC), the controller for converters of VSC is developed from the prospective of active power and alternating voltage regulation, while the eigenvalue analysis is introduced to investigate the influence of the control strategy on the system stability. In order to verify the feasibility of the control scheme, simulations have been done on the platform of PSCAD/EMTDC. It is shown that the topology of the multi-infeed VSC-HVDC can provides a cost-effective way to supply power to the receiving grid, which is also of satisfactory control effects.
Based on distributed parameters, a new location method is presented for phase-to-phase fault on three-terminal HV transmission line by using electric data at terminals. The fault voltage is calculated by the voltage and current data measured from the protection. The fault location function is provided, of which the phase characteristics are applied to decide the fault section. The only step point for the phase of fault location function corresponds to the fault position. As a result, the method avoids the distributed capacity effect by modeling with distributed parameters, the load current effect by considering fault voltage, and the transition impedance effect by phase step of fault location function. It is shown from the simulation by PSCAD/EMTDC that the method is of high range accuracy, regardless of fault location, transition impedance and load current.
The platform of 1 000 kV series compensation device is much larger than that of 500 kV on area, quality and installation height. Therefore it is of great importance to investigate the hoisting technology for platform of 1 000 kV series compensation device in detail. Concerning different plane layouts in field, three schemes for platform assembly on ground are proposed. In addition, three platform hoisting schemes are proposed by one crane, two or four cranes combined respectively, and compared from technical and economic view. The scheme by four cranes combined is applied in UHV DC test base, of which the effectiveness is verified.
During the extension project of UHV AC testing demonstration engineering 1 000 kV Nanyang substation, a 1 000 kV series compensation(SC) device platform is installed, of which the size, quality, installation height etc. are more higher than those of 500 kV one. The demand of platform installation with great difficulty is very high. In this paper, the 1 000 kV SC platform installation experiences of Jindongnan side are summarized, providing references for construction standardization of UHV substation.
The key technology for the tower erection construction is studied in ±500 kV double-circuit DC transmission lines project from right-bank station of Xiluodu to Guangdong. Based on the special type of tower and the topographical features along the lines, the modular scheme for tower assembly is recommended by the holding pole internal-suspended and external(internal)-bracing. In addition, the lifting construction technology for the tower crossarm is introduced, providing technical support and guidance for the project construction.
Aiming at the cracks of welding joint for 12Cr1MoVG steel header links of the grade I desuperheater of boilers in the ultra-supercritical units, the weldability of 12Cr1MoVG steel and technical difficulties of crack repair welding for the header links are discussed in the paper. The welding conditions and the post-weld heat treatment in the entire process from the pre-welding treatment to welding inspection are introduced. It is shown from the results of welding inspection that the repair welding quality of welding joint for 12Cr1MoVG steel header links in desuperheater can be ensured by the repair welding process.
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