Wide-area damping control system provides a new chance for improving the damping character of inter-area mode in interconnected power network. In order to optimally select feedback signal, the distribution feature of active oscillation power is calculated based on eigenvalues analysis and traditional control theory in IEEE 10 generator 39 bus system. Inter-tie line active oscillation power can be an optimal feedback signal in wide-area damping control because of its excellent signal power and signal noise ratio. Damping controller location can be selected by calculating residue and residue ratio from the transfer function between generator and inter-tie line active power. A general process is deduced base on eigenvalues analysis and system identification technology in optimal selection of feedback signal and controller location in wide-area damping control system. As a result, the calculation complexity can be reduced by it in bulk power network. signal power and signal noise ratio. Damping controller location can be selected by calculating residue and residue ratio from the transfer function between generator and inter-tie line active power. A general process is deduced base on eigenvalues analysis and system identification technology in optimal selection of feedback signal and controller location in wide-area damping control system. As a result, the calculation complexity can be reduced by it in bulk power network
Based on testing comparison, the paper makes a systematic analysis of the differences between the homemade shot-blasted S30432 tubes and the imported shot-blasted Super304H tubes in terms of surface appearance, microstructure features and hardening effect of the deformed metal layer. The study results indicate that the hardening effect of shot blasting mainly depends on the eveloping extent of the broken-grain sub-layer and the multiple-slipped-grain sub-layer in the deformed metal layers, especially the broken-grain sub-layer. The homemade SB tubes are inferior to the imported SB ones not only in the thickness and homogeneity of the broken-grain sub-layer and multiple-slipped-grain sub-layer, but also in the depth，hardness and homogeneity of the effective hardening layers. Therefore, the domestic manufacturers still lag behind the foreign counterparts in shot blasting techniques, and needs further modification and improvement.
The local yielding of the tower leg node occurring in the full-scale test of the first SZT2 tubular tower for the 1 000 kV AC double circuits is analyzed and checking calculation iscarried out according to the newly-published industrial code Q/GDW 391—2009. A FEA model is established for the failure nodes by the software ANSYS and simulation analysis is carried out, which indicates that the results of theoretical analysis and FEA simulation is in good agreement with the testing results. In the end, several alternative design schemes are compared for the nodes and the optimal model is analyzed by FEA and some suggests are proposed to prevent local yielding.
According to the characteristics of large wind speed，large span and high suspension of the Zhoushan large-crossing project, an analysis is conducted on the selection of the optical fiber composite overhead ground wire（OPGW）in terms of mechanical properties, lightning performance and vibration design, and an appropriate OPGW design scheme is proposed for the project.
Large-scale conductor galloping of transmission lines occurred three times in Henan province from November 2009 to March 2010 caused by atrocious weather including gale, freezing rain and snow . Among them, the galloping of Henan 500 kV transmission lines caused such faults as line trip, tower cross arm damage, bolt desquamate, jumper drainage line damage, insulator and spacer damage and damper slip, which badly affected the normal operation of Henan power grid impact. The paper makes a statistical analysis of the galloping damages in terms of the extent and features and analyzes the galloping genesis and the causes of grid damages. Based on the anti-galloping experience of Henan power grid, some anti-galloping measures are proposed according to the galloping damage characteristics of transmission lines.
In recent years, the accidents caused by galloping of power transmission lines frequently occur, and the area affected by galloping is increasing. Thus it is important to make a galloping distribution map for differential anti-galloping design both in technical and economic aspects. The core for making a galloping distribution map is to establish a scientific zoning method for galloping region. This paper introduces the galloping frequency method and galloping coefficient method and compares their application ranges and their merits and disadvantages. A case study is carried out by taking the Panjin and Dalian regions of the Liaoning provinces as an example and galloping coefficient method is used to make the zoning map of galloping. The case study shows that the distribution of galloping intensity obtained by the galloping coefficient method is in agreement with the practical situation.
The SZ2U tubular steel tower, 103.6 m in height and 132 tons in weight, and made of the Q460 high-strength steel, is a full-scale testing tower applied in 1 000 kV UHV AC double-circuit transmission line project. The test was carried out according to the standard DL/T 899—2004“Loading Tests on Tower and Pole Structures of Overhead Line”under 8 different operation conditions, including wind, anchor-wire, broken wire,and so on. The testing results show that the actual displacement and stress of the tower SZ2U are within the limits of deformation and member’s bearing capacity respectively; the strength and stiffness of the testing tower meet the design requirement with a certain safety margin, and the joint construction and flange connection are reliable. Application of the Q460 high-strength steel in UHV transmission tower design can not only meet the requirement of design code, but also reduces the weight of the transmission towers. It is therefore recommended to use it through pilot projects. In addition, the secondary moment of the tower’s primary members is measured during the full-scale test. A comparison of the measured result and the theoretical values indicates that the effect of secondary moment of the primary members under the varying slope is prominent, and it is therefore recommended to establish the finite element model, the finite element model of node rigidity if necessity, to check the strength.
The promulgation and promotion of the Code IEC61850 provide a basic platform for development of digital substation. In this paper, the current situations and problems of the Baicheng 220 kV substation are introduced and analyzed, and a renovation scheme is proposed according to the weak points of the substation, which includes configuring a DF1900 monitoring system in the substation level, configuring a DF1925 controlling system in the bay level and putting in electronic transducers in the process level. A technical assessment is made on the renovation scheme in terms of its reliability availability and flexibility, which shows that the renovation not only improves the reliability and availability of the digital substation, but also enhances the flexibility of the system. Moreover, the renovation significantly saves the cost for purchasing the primary equipment for the substation with good economic results, and provides a new thinking for transforming the traditional substations into digital ones.
Reducing the transmission tower’s window dimension is important for lowering the overall project investment. The paper analyzes the factors that determine the transmission tower’s dimension and proposes a designing scheme of T-shaped insulator string in middle phase. The use of T-shaped insulator string has reduced the tower’s window dimension and weight, and decreased the electric field intensity and the transmission corridor width, subsequently improving the anti-lighting level and transmission capacity of transmission lines. So it is recommended to use the T-shaped string under better ground conditions to minimize the project investment.
The damage data of the May 12th Wenchuan Earthquake show that the anti-seismic capacity of such structures as the main control buildings of various-level substations is poor. It is therefore essential to adopt the seismic isolation technology to improve the anti-seismic capacities of the main control buildings of the key substations situated in earthquake-prone areas. According to the structural characteristics of the main control building of the Linjiang 330 kV substation, the seismic-isolation bearing is selected and layout design is conducted for the seismic-isolation layer of the main control building, and the seismic-isolation design is analyzed and checked by FEM. It is concluded that seismic isolation technology can effectively reduce the earthquake response of the main control buildings and the expected objectives of the seismic-isolation design are achieved.
On the basis of an analysis on the status quo of HVDC projects in China, two general construction schemes of DC central control center are proposed and comparative analysis is conducted on their differences and difficulties. It is concluded that construction of DC centralized control center is feasible and necessary, and will bring a significant change to the mode of power grid management and operation, and achieve considerable economic benefits and further enhance the safety and stability of power grid.
Taking the Hebei power dispatch data network (SGDnet) as an example, the paper discusses the technical problems encountered in planning and construction of dispatch data network such as network topology, internet protocol(IP) address planning, open shortest path first interior gateway protocol (OSPF) and virtual private network (VPN), and proposes solutions and basic principles.
In order to ensure the safety of indirect dry cooling tower and to reduce the project cost as far as possible, it is necessary to carry out structure optimization study for the indirect dry cooling tower. The paper analyzes the influence of variation in tower laryngeal height and tower shell thickness on the integral and local stabilities of the tower, and on the tower’s amount of works. The principle and method for structure optimization of the indirect dry cooling tower are introduced and the structure optimization design is conducted based on practical project.
The vibration isolation efficiency of spring vibration-isolation foundation is analyzed with single degree of freedom (SDOF) system, two-degree of freedom system and multi-degree of freedom system. The displacement theoretical formula of the isolation efficiency is deduced with two-degree of freedom vibration equation. It is concluded through vibration equation and finite element analysis that the general average isolation efficiency of the single degree of freedom system is on the high side, while the general average isolation efficiency of two-degree of freedom system is close to the finite element analysis result; the nominal unbalance phase has some effects on the calculated isolation efficiency and the square root of the sum of squares (SRSS）method can be used to calculate the isolation efficiency in actual engineering design.
Numerical simulation is conducted on the performances of turbine stage with labyrinth diaphragm seal and labyrinth diaphragm seal with lateral teeth respectively and some parameters are obtained such as the turbine efficiency, the main aerodynamic parameter and the leakage flow. The paper analyzes the influences of two different gland seal structures on the turbine stage, and the flow condition of seal flow field.
The No. 1 and 2 roller screen and coal crusher of the Datang Zhuzhou Huayin 2 × 300 MW units frequently have such faults during operation as coal deposition, coal block, difficult start-up and motor burnout, which have seriously affected the safe operation of unit. An analysis is conducted on the fault causes of the roller screen and coal crusher and some improvement measures are proposed. After renovation, the equipment works well and can meet the production requirements.
The clogging problems of pneumatic fly-ash removal system has seriously affected the safety operation of power plants. Based on an extensive investigation, the causes for clogging problems of pneumatic ash removal system is analyzed and categorized, and it is concluded that the insufficient pneumatic fly-ash removal capacity caused by variation of ash properties is the key factor for the clogging problem. The actual factors that lead to the clogging problem of fly-ash removal system are analyzed and corresponding solutions are proposed, and some proposals are put forward on how to avoid the clogging problem of pneumatic fly-ash removal system.
Coal fire-caused mercury emission has become the fourth major pollutant after dust, SO2 and NOx, which has attracted widespread concerns. This paper introduces the existing mercury-removal techniques used for coal-fired units, and the application of the US mercury control process, and highlights the features and application of two major technologies, including the activated carbon injection (ACI) and the simultaneous multi-pollutant removal technology. In the end, relevant suggestions are proposed on process route selection of mercury control for coal-fired power plants.
With the commissioning of large-scale circulating fluidized bed units, it is very difficult to realize the input of the automatic control and automatic generation control (AGC) functions of the fluidized bed unit, due to its large thermal inertia and hysteresis, and the strong coupling between parameters. Through coordinated control strategy optimization of the first domestic 300 MW external circulating fluidized bed unit, the thermal inertia problem is overcome. By keeping the mass balance, energy balance and bed pressure balance, optimization of the coordinated control system improves its response speed to the main steam pressure derivation through controlling the fuel quantity. Optimization of the secondary air flow control on the upper and lower layers improves the combustion efficiency and overcomes the strong coupling between main steam pressure, bed temperature and bed pressure so as to make the unit adapt to the large inertia and nonlinearity produced by the large quantity of bed material in the furnace. The AGC function is eventually put into operation and satisfactory result has been achieved. On the basis of the problem of the final fluidized bed unit into AGC function, and achieved satisfactory results.
The digitalized power plant is attracting increasing attention，due to its advantages in power plant’s safe, economic and high efficiency operation management. Many studies have been carried out about how to construct digitized power plants. Based on the practice of Guangdong Electrical Power Design Institute in construction of digitalized power plants, this paper studies collaborative and 3D design technology, for the purpose of promoting the construction of digitalized power plants.
To research the joint construction of FRP（fiber reinforced plastics）towers, three alternative schemes, including embedded metal part, plug and metal sleeve, are compared and the metal sleeve scheme is selected. The selected metal sleeve scheme is optimized in terms of node reliability and deformation control through ANSYS simulation and full-scale testing. The paper studies the relationship between joint stiffness and deformation coordination and that between local deformation and joint failure, and explores the joint scheme between FRP tower’s cross arm and tower body as well as hardware. Full-scale testing is also conducted for the cross arm joint.
For a study on application of FRP (fiber reinforced plastics) in 35 kV power transmission tower, this paper, on the basis of a 35 kV power transmission project in Shandong province, explores the design method of FRP towers for 35 kV power transmission through full scale test and ANSYS FEA from the aspect of tower selection, material selection, structural design and node optimization. The result shows that the design method is safe and reliable for 35 kV power transmission FRP tower, which provides a technical reference for engineering application.
Optimization design is conducted for the connection of the composite insulator and the line hardware in suspension string, strain insulator string, L-shaped string, V-shaped string, reverse V-shaped string of the overhead transmission lines. The metallic ball and ball socket on both ends of the composite insulator are changed into round haplopore and bolt connecting structure, which removes the R-shaped fitting pin and realizes bolt connection with hardware. The manufacturing process of terminal hardware becomes simpler. Two or more inner-arc U-shaped hoops are used for one or both terminal hardware in direct connection with the composite insulator, which increases the axial rotation freedom of the composite insulator in suspension string, strain insulator string and V-shaped string, avoids any end torsion of composite insulator, and guarantees its mechanical behaviors. Through this work, the transmission line will operate more safely and reliably and the goal of full-life operation of overhead transmission line will be attained.
Wearing damage of bearing shell and journal has frequently occurred in recent years during turbine starting-up in several newly built power plants, which has caused serious impacts on the power plants’ safe operation and economic benefits. This paper introduces the wearing damage of the bearing shell and journal occurring during the first starting up of a power plant’s the 1 000 MW turbine, analyzes the causes and proposes some treatment and preventive measures.
Due to imperfect renovation of the unit 4’s controlling and security systems of the Guodian Jiujiang Power Plant, some problems occurred such as the servomotor of medium-high and medium pressure governor steam valve was not sufficient in openness during the static test and the movable test of the main steam valve could not be carried out normally. An analysis was carried out on the causes and practical countermeasures were taken to eliminate the renovation-caused problems, which are proved to be effective.
The paper introduces the causes of the condenser terminal temperature difference, and analyzes the terminal temperature difference control measures from three aspects, including ensuring the maximization of heat-exchange area, guaranteeing the vacuum system, and ensuring the tightness of the vacuum system. According to the actual problems encountered during application, some solution measures are proposed and may be referred to by similar construction.
The tubular tower for Zhoushan island-mainland large-crossing transmission project, 370 m in height, is characterized by super height, large weight and huge body and has high risks in tower erection. A safety planning is carried out and implemented in terms of safety training, safety protection facilities, safety monitoring system and control and communication system, which effectively avoids the safety risks caused by possible object falling, object impact and mechanical damage.
Based on the installation practices of converter transformers of the Xiangjiaba-Shanghai ± 800 kV UHV DC demonstration project, the paper analyzes the procedures, key links and controlling process for installation of the UHV converter transformer, and proposes the installation techniques for UHV converter transformers under extraordinary conditions.
Based on the characteristics of the Xiangjiaba-Shanghai ± 800 kV UHVDC transmission line，this paper introduces the pulley hanging scheme of the tension stringing method called“one-drag-four plus one-drag-two”. In this scheme the L-shaped eccentric joint-board is designed to avoid the unbalance problem of the stringing pulley block.Construction practice demonstrates that the L-shaped joint-board has high efficiency in application and can solve several key problems in stringing construction. The design of this scheme and construction process can provide a reference to relevant technicians.
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