On the basis of the random physical models of wind and wave, a wind and wave coupling method was proposed based on its physical mechanism. Then, a more reasonable pile-soil interaction mechanism was introduced to establish an integrated offshore wind turbine system model. Taking the offshore wind turbine system in the East Sea of China as an example, its dynamic response analysis under the combined wind and wave loads was carried out.
Because of the Tibet power grid is in the early stage of development and its AC system is very weak, the connection of Qinghai-Tibet DC transmission line will cause the situation of weak system with big DC power and the unblock mode with 10 % rated power not satisfying the systems operation requirement. This paper studied the minimum start-stop power and method for the Qinghai-Tibet DC project in order to make system operation safe and stable, and proposed monopole and bipolar start-stop methods. The special requirements of AC smoothing reactor and converter valve were also put forward for the minimum start-stop power. The DC start-stop method of unlock/block with 10% rated current and 25% rated voltage can implement monopole unlock/block with 2.5% rated power and reduce the impact of DC start-stop on the AC systems frequency. This start-stop method can ensure the system operation safe and stable, which has been successfully applied in the Qinghai-Tibet DC interconnection project.
The rock anchor foundation applications for transmission line in investigation, design, construction and detection were studied. Some technical measures were proposed, such as using high intensity steels and swelled rock anchor. And the hole bottom expanding foundation, the composite foundation and group steels foundation could enlarge the application scope of rock anchor foundation in transmission line, which could provide references for other engineering applications of rock anchor foundation.
The season variation between distributed wind power output probabilities and receiving end loads is inconsistent. Based on Huaneng Shaanxi Langergou distributed demonstration wind farm, this paper proposed a dispersal access program for distributed wind farms to achieve a complete balance between wind power output and access point load. This program can change wind power capacity at different access points by optimizing wind generation compilation and main electrical wiring to adapt to the season variations of grid loads, solve the problem that single point access scheme cant meet the condition of wind power output not into grid in different operating modes, and provide voltage support for distributed grid. In addition, this paper presented a conception of optimizing combination plan and improving main electrical wiring for large scale distributed wind farm, which had enlightening significance to distributed wind power research.
The three-dimensional digitalization transfer of Qinghai-Tibet ± 400 kV DC interconnection project aims to promote the application of three-dimensional design technology in the converter stations design. The project made effort to realize professional transfer information with universal platforms by adopted universal three-dimensional design software and considering the convenience of owner management. When Lhasa and Golmud stations were transferred to the operation company, the real three-dimensional models and the classified construction drawings of stations were provided, which was beneficial to these two stations owner management and operation maintenance.
The paper introduced the design principles of ±500 kV Tuanlin converter station in Jingmen-Shanghai DC transmission project, and investigated the design features, which could provide references for the design of HVDC or UHVDC converter stations.
The adaptability of large capacity nuclear power plants after accessing in Northwest grid was analyzed, which focused on problems in terms of power flow distribution, grid stability level and short circuit level. The study result shows that the planned power grid of Northwest can satisfy the need for nuclear power plant with unit capacity of 1.75 GW, but the number of Shaanxi Ankang or Ningxia Wuzhong nuclear power units should not be more than 1 in, the number of Gansu Linxia nuclear power unit should not be more than 3.
Based on the design of the auxiliary power system of Xuzhou 1 000 kV UHV substation, a primary step-down system and a secondary step-down system were presented. According to the technological and economical comparisons, the primary step-down auxiliary power system was recommended, and two wiring principle schemes for auxiliary power system were proposed, of which different from UHV demonstration engineering was recommended by reliability analysis.
The connection scheme of gas insulated metal enclosed transmission line (GIL) can save investments of bushing and GIL pipeline, optimize arrangement of AC yard, improve the reliability of connection and reduce the workload of maintenance, for the station-service transformer in UHV converter stations. An active electronic transformer was used to solve the problem that the price of gas-insulated switchgear (GIS) was a little high. This method can reduce the construction cost on the premise of reliability, and effectively solve the saturation problem of small ratio current transformer at high voltage side for the station-service Transformer in UHV converter stations, which can promote the application of GIS electronic transformer in UHV converter stations.
In order to improve the construction quality and adapt to the development of intelligent substations, this paper analyzed several optimization problems for substation cable laying engineering from a design point of view, and put forward design optimization methods. Based on the engineering practice in Wuning 500 kV substation, the technical and economic issues of design optimization were investigated to verify the feasibility of design optimization methods.
The construction of green substation was proposed to implement the technical-economic policy of resource conservation and environmental protection. But the construction of green substation is a new topic, and there is no standard for its construction requirements. This paper propesed a electrical design method for green substation based on the practice experience of Four Savings-Environment Protection substation construction in mainland and Hong Kong in recent years, which could provide references for the design work of similar substations.
The conventional parameters calculation of grounding grid can only obtain the value of grounding parameters, but can not directly reflect step voltage, contact voltage and surface potential distribution. A new calculation method for grounding grid parameters was proposed according to the current field theory, in which the grounding grid was mathematical modeled by boundary element method, the grounding resistance was calculated by Matlab in vertical two layer medium demarcation, and the step voltage, the contact voltage and the surface potential distribution were imaged by Matlab graphical function. The result shows that this calculation method is precision and can be applied in the investigation of grounding grid parameters, which provides a technical reference for engineering application.
Because of the geology, the climate and other reasons, the lightning accident occupies a large proportion of the transmission lines trip-out in mountainous area, which seriously influences the stability of the power grid and the power supply reliability. This article investigated the statistical data of lightning trip fault for 35 kV and higher transmission lines in Chongqing Changshou mountainous area in recent years, introduced the treatment scheme of lightning accident, judged the pattern of lightning accident based on the theory and site experience, and briefly analyzed the lightning trip fault. The process of lightning protection regulation was researched to propose some new ideas for lightning protection, which was popularly used in Changshou power grid. The results can provide references for transmission lines lightning protection in lightning area and mountainous area.
The overall calculation model and single computational model was built for the space triangle pipe truss of the gas turbine room roofing. The simplified model for the gas turbine room roofings truss bearing was analyzed, on the basis of using hinge connection, sliding connection, and two support restraint. This paper compared the calculation results of different simplified models for the gas turbine room roofings truss, and investigated the impact of truss support restraint, gas turbine rooms structural stiffness, roofings concrete slab, and trusss single beam calculation model, which could provide references for the engineering design.
It is required that power plant units can run in island operation in the contract with a foreign element, which is a strict requirement for the safety of units. During the commissioning process of India Sagardighi 300MW power plant unit, there were many problems due to the existing logic limitations, such as reheater overpressure in island operation, frequent action of spray water adjusting valve in low pressure (LP) bypass, poor regulating quality, spray water isolating valve in high pressure (HP) bypass opening without command, superheating in turbine with reheater overpressure, and turbine trip with high HP exhaust temperature. In order to solve these problems, a new logic for bypass system is put forward. The practice shows that the application of the bypass systems logic can significantly reduce the probability of problems in island operation.
At present, distributed control system (DCS) plays important roles in power plant, but still has some problems. So the performance test for DCS is attracting more and more attention. This paper introduced the performance test technique for DCS in terms of application. Some test techniques and results were presented, such as analog signals real time test performance test, controllers processing period test, and channel anti-jammings function test. These test techniques have been successfully applied in ten units, which test results are especially useful for the on-site DCSs performance tests.
This paper introduced and compared four kinds of common enclosed coal yards common in China. The result shows that rectangular enclosed coal yard and paralleling multi-bunkers of circular silo are applied only to special situations with narrow space and high environmental protection requirements. Circular enclosed circular coal yard has some features compared with strip coal yard, such as small floor area, less earthwork, high site utilization, high degree of automation and moderate project cost, which is worthy of popularization and application.
Because of coal price is more and more expensive in China, coal-fired power plants use low quality coals deviated from the designed grade in order to reduce costs, which will lead to the boiler pulverizing system output is limited, the security and the economic performance is decreases. The coal applicability for pulverizing system in 1 036 MW coal-fired units boiler was investigated based on the experimental research to obtain the maximum output of coal mill using different coals. This paper adjusted the wind-coal ratio of coal mill and proposed some suggests, such as it should do regular calibration for primary air flow, and the calculation of minimum running air flow should consider the moisture, viscosity and other parameters of coal.
Mill rejects are a kind of solid wastes in coal-fired power plants, which can cause a lot of air pollution problems. At present, there are several treatments for mill rejects, but they all have some shortcomings. A positive pneumatic conveying system general used for powder was successfully applied to mill rejects with special conveyor, valves and running process, which could make a great breakthrough on the technology and application. With advantages of simple, flexible layout, small occupation of land, no water wasting, and low power consumption due to the conveying air coming from the air compressor station in power plant, this technology is worthy of popularization.
This paper introduced the utilization of double column suspended guyed tower abroad, the form-finding of suspended cable and the size determination of tower. The dynamic characteristic of double column suspended guyed tower was analyzed using finite element method with guy vibration in first 16 dynamic models. The result shows that new type fittings need further studying due to the large stress of guy lines and fittings. The advantages and shortcomings of double column suspended guyed tower, self-supporting tower and traditional guyed tower were compared, and the results showed that double column suspended guyed tower was most economic when land occupation was not restricted.
The reasons of shielding failure in transmission line were investigated, as well as the method of lightning shielding failure prevention. Based on operation experiences of transmission line in Jiangxi Province, the reason of shielding failure trip of JG and ZGUT type tower were emphatically analyzed, and a new measure was proposed to prevent shielding failure trip. The results show that TH-lightning rod installed on the cross arm at wire suspension point of JG and ZGUT type tower can reduce the shielding angle of mid-phrase jumper-line of JG type tower and that of mid-phase conductor of ZGUT type tower, which can greatly decrease the lightning failure trip rate.
At present, Qinghai-Tibet interconnection project is the highest and largest plateau power transmission project with the longest line through the permafrost zone in the world, which needs strong material support during construction process. In order to solve various problems of material support, this paper innovation built a material support mechanism for plateau power engineering through the innovation of management model. According to the theory of project management and matrix management model, the exploration and practice for the material support mechanism and project management were completed successfully in Qinghai-Tibet interconnection project.
A forced outage incident of the DC system had happened in xingren convertor station, due to a logic defect in valve cooling control and protection system, on December 10, 2010. In order to avoid similar accidents, this paper deeply analyzed all the valve-cooling control protection logic in Yunnan-Guangdong UHVDC transmission project. An improvement for protection logic was proposed, which was to cancel the fault trip logic for two redundant sensors. The result shows that the reliability of Yunnan-Guangdong UHVDC transmission project is greatly increased.
Base on the units starting-up and commissioning process in a power plant, this paper introduced the structure characteristics and starting-up processs control technologies of 1 000 MW steam turbine with SIEMENS technology. Problems in starting-up and commissioning process were analyzed, and some proposal were put forward for the commissioning of 1 000 MW ultra-supercritical unit and the optimization of boiler steam-blowing, which could provide references for other units commissioning.
The bid section 7 in the Qinghai-Tibet DC power transmission project is located near the Tanggula Mountain，where ecological environment is bad. Many environmental protection measures were used in the construction process, such as fixing the construction range, limiting the transport line, the ground of the transport routes being covered with grass and coir mats to avoid direct contact with the vehicle which may cause damage to vegetation, stripping the ground turf before excavation construction and replanting it in time, taking insulation measures to prevent the frozen soil melting, and vegetation restoration using cultivation method for the vegetation of poor recovery effect under stripping and replanting. These methods can effectively protected the construction site environment and minimize the adverse effects on animals, which can provide references for the environmental protection and vegetation restoration of power transmission project in high-altitude alpine regions.
This paper analyzed and compared three leveling and alignment methods for inserted angle-steel with an emphasis on suspension type. The polar coordinate method and simplified method were proposed for calculating the size of suspended angle-steel with reserved height, based on the calculation model of suspended angle-steel without reserved height and the rotating principle of foundation center. The operation steps, notices and engineering calculation examples of suspension method for inserted angle-steel were introduced. This method has the characteristics of simple operation, satisfied quality and high efficiency, which can be popularly applied in the construction of transmission line tower foundation.
This paper introduced the generator stator hoisting scheme for conventional island generator stator in Fuqing nuclear power plant, which was using hydraulic lifting device and matching hoisting framework, and making mechanical analysis for hoisting framework with finite element analysis model. The results show that hoisting framework has the advantages of compact structure, safety and reliability, the application of truss column and column base box in pillars can reduce the requirement of foundation, and new sliding method of incremental launching is smooth, non-impact, safe and reliable. The steel wire-type hydraulic lifting device has some characteristics, such as large lifting capacity, compact structure and coupler lock, which is very suitable for the hoisting work of generator stators.
