The purpose of promoting the typical design of electrical system for wind farms and modular design method is to improve the design scheme quality and standardization. In this paper, the typical design of electrical system for a wind farm includes the standard designs of wind turbine transformer, collector circuit, substation transformer, primary and secondary electrical systems. As a result, two typical schemes for wind turbine transformer, eighteen modules collector circuits, fifteen alternatives for substation transformer, and six alternatives for wind power output are presented. The typical design and the analysis results shown in this paper is of great importance for promoting the coordinated development of power supply and power grid.
High frequency problem occurs when the local power network is disconnected from the main power network. Based on this, the dynamic process of frequency in the local power network is simulated, and the high-frequency cutting machine schemes are analyzed. It is found that the cutting approach is of great significance to the frequency recovery of local power network, that provides a reliable basis for dealing with such incidents.
In order to assist developing the independent intellectual property key technology of 1 000 MW super-critical lignite boiler, this paper studies the type-selection optimization of pulverizing system used for 1 000 MW super-critical lignite boiler. The study is based on the type-selectionof boiler, coal pulverizing system, and coal mills from Datang Keshiketengqi 2× 1 000 MW super-critical thermal power plant. The type-selection parameters of coal pulverizing system is proposed for 1 000 MW power plant, The parameter scope of the pulverizing system is also proposed, which could give technical support for the development of 1 000 MW-order super-critical lignite boiler.
The precast concrete assembly foundation for Qinghai-Tibet AC 750 kV/DC ± 400 kV grid interconnection project in frozen soil area was tested under compression load.The mechanical co-working properties for the different parts of the foundation were analyzed based on the monitoring results of structural displacement, soil pressure, and fitting stress. Under compression load, both the displacement and the changing regularity of the ring flange connecting the column and the bottom slab and the joint seam of the two consolidated bottom slabs comformed with that of the top plane of the foundation.Two stages of elastic and elastic-plasticity were observed according to load-diplacement curves of the foundation. The stress of the channel beams increased with the compression load and were found in elastic stress status. Under the compression load, the two edges which were parallel to the the joint seam of two consolidated foundation slabs had a tendency to upwarping. However the displacement of all angular measuring points were less than that of the top plane of the foundaiton. The diplacemnet and the stress of the different connected parts redistributed until the new banance developed. As a result, the different connected parts of the precast concrete assembly foundation co-operated to carry the compression load. The structrual characteristic of the assembly foundaiton, the gaps among the assembly parts, the discrepance of the nut screwing up and the mismathing tolerance during consolidating were the key factors to determine the performance of the foundation. Under compression load, all structural parts of precast concrete assembly foundation had good entirety.
The fretting corrosion behavior of the LGJ150/25 aluminium conductor steel reinforced（ACSR） conductor is investigated under industrial atmosphere corrosion condition and two different fretting amplitudes, based on the fretting abrasion/ fatigue testing equipment developed by the others. It is shown that the morphologies of the abrasion marks after fretting corrosion are basically similar to those after dry fretting wear, but there are corrosion products on the abrasion surfaces and corrosion holes along the edge of the abrasion marks. After fretting corrosion, the tensile strength of the Al strands decreases and the resistivity increases, so that damage of the conductor is more serious and becomes worse by increasing the fretting amplitude. Fracture of Al strands after fretting corrosion originates from the I and II-type fatigue cracks under the abrasion marks, which accelerates fretting corrosion via an electrochemical reaction and forms the corrosion holes. It possibly acts as the key factor of the fretting damage of ACSR conductor under atmospheric corrosion condition.
Based on the theoretical analyses that power frequency overvoltage generated by long-distance transmission line can be restrained by magnetic controllable reactor(MCR) effectively, the restraint of power frequency overvoltage by MCR is simulated in three different working conditions, that is, no-load line capacitance effect, asymmetric earthing and sudden load shedding. It is shown that parallel MCR is effective to restraining the overvoltage, of which the installation in the tail end of line is better than in the head end and in two ends.
By analyzing the functions of the static var compensator (SVC) applied to extra high voltage (EHV) AC power transmission, the control strategy of SVC is proposed. This strategy takes system voltage (e.g. 500 kV) as the main control objective to achieve stable voltage, increase power transmission capacity, promote voltage recovery after the failure, and depress oscillation etc. In view of the high capacity of each SVC in the EHV power grid, the measures are proposed to prevent the valve manifolds and the total circuit breaker over-current, and the voltage busbar over-voltage in the control process.
This article introduces the 110 kV smart substation project for the wind power generation center in Zhangjiakou, and analyses the technical features and implementation schemes. The main technical innovations are also introduced, which include combination of smart terminal and the primary equipment, simplification of the secondary circuit within switch, installation on the switchyard of the process-lelvel equipment, information shareing based on generic object oriented substation event （GOOSE） networks, and equipment intelligentization of the online monitoring system for the primary equiment, and intelligent control of lighting, ventilation air-condution heating, water supply and drainage within the station through linkage of the production assistance system and the video system.
In order to study the conversion method for horizontal span of power transmission tower, the force features of suspension and tension tower are considered by starting from the tower design. The main control conditions and their influences on material selection and composite indicators of tower are analyzed. The reason is provided that the span conversion should be considered or not for designing the suspension and tension tower. In addition, the calculation principle and method of span conversion are presented for suspension tower.
Rock anchor foundation in transmission line is considered as a new type of foundation which is more environment protective and economical in mountainous areas. Steels of class HRB335, HRB400 are broadly used, but the yield strength is relatively low. Moreover, the economical efficiency is not obvious when the force of foundation is big. In this paper, it was found that the applying of high intensity steels on the current type of foundation is feasible, economical, safe, reliable, material-saving and environment protection as well. The application was found to allow full play to the shear performance of rock, the cohesive strength of both the rock and mortar, the cohesive strength of steel and mortar as well.
The outlet circuits of HVDC system are complicated and exist such problems as the hard wiring and fieldbus are blended together. Based on the analysis of the HVDC transmission systems in operation, this paper discussed the outlet circuits of three kinds of HVDC transmission systems, which is the early HVDC transmission system, the short-term HVDC transmission system and HVDC transmission system with fieldbus, and put forward some operational improving suggestions.
The horizontal bearing capacity of fine rock concrete micropiles is studied by field test. It is shown that the horizontal design bearing capacity of micropile foundation should be calculated by horizontal allowable displacement. Based on the test results, the design method of the horizontal bearing capacity is investigated in single micropile and pile groups. If the design parameters are reasonably chosen, the horizontal bearing capacity of micropile foundation could be preliminarily designed by the provided method.
In conventional design of transmission lines, independent column foundation is individually allocated to each leg of tower. By analyzing the transmission tower foundation forces, four separate columns are united as a whole, the uplift and down force of foundations transmitted by cross beam, and the uplift force calculation is changed to bending force calculation. Furthermore, this design principles and methods of self-balanced cross foundation are introduced, and some issues of design features and process discussed. The self-balanced cross foundation is compared with other foundations, of which the applicability and shortcomings are analyzed. It is found from the calculations that the self-balanced cross foundation has the advantages of shallow depth, high reliability, perfect integrity, strong ability to resisting horizontal displacement, and better economy. Therefore it is worthy to be popularized, especially for the foundation designs of special geological conditions.
By the analysis of seismic hazards of transmission tower, the existing aseismic checking calculation range has effect on the aseismicity of transmission lines, and the range needs to be adjusted. The recommended methods for aseismic design of different transmission tower structure are provided based on static method, response spectrum method and time history method etc.
With the increasingly difficulty of current power grid construction and the rapid development of renewable energy sources, distributed generation and smart power grid technology, HVDC flexible technology provides a new approach to make up for conventional HVDC or HVAC transmission technology. Based on this, the features and economies of HVDC flexible technology is summarized. Following the introduction of practical applications abroad and in accordance with the actual requirement of energy sources and power in China, the application perspectives of HVDC flexible technology are analyzed on renewable energy sources development, distributed generator connection power supply for isolated area and urban power network. Furthermore, the suggestions for studying and popularizing the new technology is provided.
Distributed resources (DR) have important impacts on power loss of distribution network system, including the location, capacity and power factor of DR. Based on radial single circuit network and uniform distribution constant power load model, the mathematical relations between reduction of power loss and location, capacity and power factor of DR were deduced for single DR inserting, and generalized for multiple DR inserting. The optimum location and capacity of DR were obtained. The influence of DR inserting on the power loss of distribution network was simulated and analyzed. The conclusions investigated in this paper provided theoretical references to optimal operation mode and power network planning of DR.
During the ultra-supercritical turbine of 1 036 MW unit being stopped, metal temperatures of regulation stage in high-pressure cylinders and inner wall in medium-pressure cylinders decline slowly, and negative differential expansion of high- and medium-pressure cylinder is hard to control. Therefore, the optimization of practical quick shut-down curves and the precautions and requirements for steam turbine operation are considered. Based on this, the quick cooling scheme including three stages, and the recommend curves of quick cooling for similar units are provided. As a result, the shut-down and cooling are quick and safe, the cooling-down time is considerably reduced, the maintenance period shortened, and the unit available coefficient improved. The quick cooling scheme, with remarkable economic and social benefits, provides reference to similar units.
Based on the features of the auxiliary system of 660 MW direct air cooling turbine from Guohua Dingzhou Power Generation Co., Ltd., the problems encountered in commissioning process are analyzed and the solution is proposed thereafter. The investigation results can be referenced for similar systems.
Electrostatic precipitator is widely used in smoke and gas pollution control of power plant, the design precision of whose components can affect its installation, operation and maintenance. In this paper, the interactive parameterization design system for electrostatic precipitator’s components is developed by application programming interface （API） secondary development, virtual modeling of SolidWorks and Visual Basic 6.0 software. The system can significantly shorten the development cycle and cost, heighten the design precision of the components, and thus reduce the possibility of electrostatic precipitator’s fault during operation caused by poor design precision of the components.
The pipe blockage occurs during the debugging and operating period of dense phase pneumatic ash-conveying system in 3 × 300 MW units of the power plant of Lanzhou aluminum plant. The causes are analyzed, and the preventive countermeasures and solutions proposed accordingly, providing guidance to the operators for judging reasons and adopting effective measurements．
The optimization of coal handling systems in thermal power plant is mainly to shorten transportation distance and decrease the number of transfer station. In this paper, the plan and advantages of chimney-traversing technology of tubular belt conveyor are introduced, whose application in sending coal of side coal bunker of 1 000 MW unit in Huaneng Haimen Power Plant are analyzed. Furthermore, the economic and social benefits are summarized.
Grounding network is an important guarantee for safe operation of power system. In this paper, a study is conducted through field test on the relationship between applied current and corrosion potential of galvanized and non galvanized Q235 and Q345 steel in different soil environments and on the relationship between the burial time and corrosion rate, and the corrosive properties of the Q235 and Q345 steel in different soil environments are obtained. The field test result shows that along with the increase of the applied current, the corrosion potential of 4 different steel decreases first before going up, with the corrosion potential of the Q235 carbon steel being the lowest; The non galvanized Q235 steel has the lowest fitting degree between the tested corrosion rate and the corrosion rate model while the non galvanized Q345 steel has the highest.
Combining with the choice of technology plan of coal pulverizing system and lignite drying system in pithead power plant, an analysis is carried out in this paper on the advantages and disadvantages of coal pulverizing systems with fan pulverizer and with mid-speed pulverizer plus lignite drying system, based on which the mid-speed pulverizer plus lignite drying system is eventually selected as the process route of coal pulverizing system. And then the major lignite drying technologies of both China and abroad are introduced. On the basis of a comprehensive comparison, the steam tube rotary dryer is selected as the main equipment of lignite drying system. Finally the lignite drying system is elaborated. It is concluded that it is very important to introduce the lignite drying technology into power industry for exploring the lignite drying process technologies that are suitable for China’s power industry.
With the rapid growth and enhanced aim of wind power, large scale development of wind power has become an inevitable trend. To guarantee the reliable and effective transmission of wind power, economic analysis is investigated based on the development conditions and transmission of wind power in our country. The selection of technical parameters and its impact on the economy are analyzed by the means of price competitiveness analysis for UHVDC transmission combined with wind and thermal power. It is shown that the wind power transmitted by UHVDC is economically feasible, and some related suggestions put forward.
The accidents repeatedly occur and have a serious impact on safety since a 660 MW unit comes into operation that bearings temperature in flow part between high and intermediate pressure cylinder increases and bearings damage. Aiming at the causes of accidents, a series of technical measures are adopted and the operation scheme is optimized with equipment manufacturing factory, effectively improving the operating conditions to eliminate potential causes of accidents.
The most difficult point of the power plant across sea/river circulating water & taking catchment engineering shield construction craft is that excavation construction needs to cross the defense dike, which can cause partly dike subsidence without proper control. Based on the characteristics of the circulating water draining engineering from one 2 × 1 000 MW unit in a power plant in Shanghai, the subsidence control measures by the shield construction method was drawn up, which can control the subsidence of dike effectively.
The diameters of most of shield tunnels in power plants of China are about 4 000 mm, while that of artesian water diversion shield tunnel, applied firstly in China, is up to 6 000 mm in Sanmen Nuclear Power Plant. In this paper, the geological conditions of water intake project is analyzed, and engineering design and construction technology of shield tunnel are introduced, providing reference for future similar projects.
The tension towers used in ± 800 kV ultra-high voltage transmission line, tall and heavy, have long cross arms. As a result of the special environment in the field installation, it is difficult to hoist the edge cross arms of tension tower by conventional methods. Therefore, a special construction method is provided to hoist the edge cross arms successfully that the main gin pole suspended in inner tower is assisted by the herringbone pole.
For providing references to construction of tension stringing, the problems related to wiring are summarized combining with the construction experience, such as proper selection of payoff tension, line length calculation and its influencing factors, wiring method, and wiring controlling etc.
