This paper studied the technical framework of new generation intelligent substation. Through the analysis on the characteristics of external operation management requirements and internal development needs, the construction goal and functional characteristics of new generation intelligent substation were put forward, and its general framework and technical route were also proposed. Finally, this paper discussed the technical subjects and research thinking of intelligent substation, such as core technology, key equipment, project design, construction technology, standard formulation and operation and maintenance management.
Small photovoltaic (PV) power station generally connects the grid at 380 V, medium PV power station connects the grid at 10~35 kV. Because the arrangement range of PV modules is small and the grid voltage is low, there is no collecting power line in the small PV power station, and in the medium PV power station, the voltage of collecting power line is equal to the grid voltage and the selection is relatively simple. However, for large-scale substation PV power station, the grid voltage is more than 66 kV, the arrangement range of PV modules is large, the manufacturing cost of collecting power line is also high, and it is difficult to make a choice between 10 kV and 35 kV. This paper built the model for a 200 MW PV power station, as well as compared the manufacturing cost of collecting power line at two kinds of voltage from the aspects of investment and loss. The research results could be a reference for the design of PV power plant and relevant research departments.
The automatic sequence control function of valve group state transition is one of the most basic control functions for DC system. The successful auto-completion of valve group state transition is also the important inspection index of working stability for DC control system. This paper introduced the implementation process of valve group state transition in Yunnan-Guangdong DC transmission project, analyzed the irrationality of current circuits design and its hidden danger. The solution method proposed has been successfully applied in Yunnan-Guangdong and Nuozhadu DC transmission projects, which has certain practical significance to the steady operation of UHVDC systems.
Taking Zhengzhou UHVDC converter station as the research object, two new ice-melting connection schemes were suggested for the indoor DC field of converter station, whose economic and technical features were also compared, based on the principle of outdoor emergency ice-melting connection and the particularity of indoor DC field. According to the recommended electrical connection form, the corresponding new electrical layout scheme of indoor DC field was proposed. Finally, the operation mode of emergency ice-melting and its superiority were analyzed. The research results can be references for the design of UHVDC indoor field in UHVDC converter stations.
More and more transmission line projects were built in miscellaneously backfilled soil areas. However, there were no special regulations on the selection and design of tower foundation, foundation treatment methods, and engineering design parameters for the miscellaneously backfilled soil. This paper investigated the engineering technology of tower foundation for transmission line in miscellaneously backfilled soil areas, and suggested the pile foundation, raft foundation, the tower foundation schemes and its applicable conditions. At last, the test methods for the determination of miscellaneously backfilled soil properties were proposed, which could provide references for the engineering design.
This paper discussed the necessity of technique reformation of capacity expansion for the 3.52 km transmission lines directly connected Qinshan 500 kV combined switch station, and analyzed the feasibility of the replacement of the 4×AF (SZ) S4A-400/45 augmented capacity conductor for the 4×LGJ-400/35 conductor. The parameter matching performance between the augmented capacity conductor and the 4×LGJ-630/45 conductor of Qinyou 5415/Qinquan 5416 newly built was also studied. The technique reformation scheme of capacity expansion can provide references for the power transmission capacity increase in the developed area where there is not enough transmission line corridors.
Enhance the coordination of components, the current carrying capacity of transmission lines could be increased. This paper introduced the calculation methods of current carrying capacity for power cable lines, and analyzed the key parameters during calculation. Based on the calculation results of current carrying capacity for 220 kV power cable lines under representative laying modes, some suggestions were proposed for the matching scheme of conductors cross-section between 220 kV overhead lines and cable lines.
With the operation of DC transmission projects increases, the DC magnetic biasing phenomena occurs sometimes in surrounding substations, which will harm the safe operation of power grid. This paper used PSCAD software for power system to build the model of DC power grid. Taking 500 kV Hanshan substation as an example, the DC power flow was calculated, when the neutral point of main transformer used low resistance or blocking capacitor. Finally, the suppression measures were adopted to improve the ability of stable operation for transformer substations.
In order to realize the data sharing and interoperability of application system, as well as the integrated technical support system for regional power grid scheduling, this paper developed the technical support platform of scheduling, which taken the common information model (CIM) as the core model and had the graphics interoperability function of panoramic visualization, based on the update of energy management system (EMS). This technical support platform can realize the unified management of models and parameters for power grid and the sharing of basic resources in Nanchang, which can effectively support the construction and development of intelligent scheduling system for the regional power grid in Nanchang.
For ± 800 kV UHV DC transmission line construction in cold regions, it is necessary to solve the design problem of low temperature brittle fracture, in order to prevent the brittle fracture of steel structure members under low temperature without reaching the yield stress. Taking ±800 kV Hami-Zhengzhou DC transmission line as the study object, this paper introduced the mechanical properties and principles of tower components under low-temperature environment, based on the theory and test results of brittle fracture under low temperature at home and abroad. Combined with practical engineering, a strength design method was proposed and the design parameters were studied in detail for steel structure members under low-temperature environment. At last, some reasonable reduction factors were recommended. The results presented in this paper could be used as references for the design of DC transmission tower.
This paper analyzed the reason of drain in block in No.3 low pressure (LP) heater in 220 MW units during the startup and debugging stage. Based on the real-time data, the original design parameters and the site situation, the drainage systems in No.2, No.3 LP heaters were modified, and the cooling water of slag cooler was adjusted, in order to solve the drain in block in No.3 LP heater. Finally, this paper suggested the solution for the influence of cooling waters backwater temperature in slag cooler on the No.3 LP heaters drain
At present, the formation and exfoliation of oxide scale of heating surface tubes in (ultra) supercritical boiler are recognized problems. When the unit is in the maximum load (maximum temperature) running, these problems will be more obvious with the increases of running time and the design value of steam temperature. This paper analyzed the cause and accident potential of oxide scales formation and exfoliation, discussed the oxidation status on different pipes at heating surface in subcritical, supercritical and ultra supercritical units, as well as compared the oxidation status on heating surface tubes before and after oxygenated treatment for boiler feed water. Finally, the measures of comprehensive treatment and monitoring for oxide scale of heating surface tubes were suggested, which could provide references for the treatment of oxide scale in other (ultra) supercritical units.
Gas-gas heater (GGH) is applied widely in the desulfurization system of large thermal power plant. There are some problems during the operation process of GGH, such as scale and plugging, poor heat transfer efficiency, much higher operating pressure difference than the design value, and so on, which seriously affect the safe operation of boilers. According to the scaling situation, this paper developed a special cleaning agent for HB-I GGH, and design the specific cleaning process, whose application had a good effect in a power plant in Anhui. The result shows that the cleaning agent has higher economic and safety benefits.
According to the problems of structure anti-seismic in international thermal power project bidding, this paper suggested the determination method of seismic parameters for the structure anti-seismic design in international thermal power plant projects, based on the analysis on some bidding documents of international thermal power plant project and seismic hazard. Finally, the corresponding relation between seismic parameters in bidding documents, seismic hazard analysis reports and that in the China seismic design cod was further discussed.
More and more biomass power plants have been put into operation recently years in China, with the problems of biomass fuel delivery increasing. These problems are mainly concentrated in boiler-front feeding system, such as fuel shagging, fuel blocking, coking and so on, which may lead to units unstable operation. Base on engineering examples and biomass fuel characteristics, this paper proposed four schemes for boiler-front feeding system in biomass power plant, and analyzed these schemes advantages and disadvantages, in order to provide references for the same type of biomass power plant on boiler design, feed equipment selection and long-term stable operation.
In order to improve the safety and reliability of external insulation for ± 1 100 kV UHV DC converter station, this paper studied several key technologies of post insulator for ±1 100 kV UHV DC, such as air gap external insulation, pollution, mechanical strength and so on. According to the technical parameters of ±1 100 kV UHV DC post insulator, the solution for those technical problems was proposed, combined with the design of ±800 kV UHV DC post insulator. The results could provide design basis for ±1 100 kV UHV DC post insulator, and technical support for the project construction and operation.
This paper discussed the necessary and feasibility of steel tube towers application in UHV AC transmission line, the challenge of large scale application, as well as the achievements in research, standardization design, manufacture ability, construction technology based on the Huainan-to-Shanghai 1 000 kV UHV AC pilot project.
According to the fracture failure of sub-conductor of 6-split conductor in 500 kV transmission line, the material test, finite element simulation and comprehensive analysis of fracture failure were carried out. The analysis results show that the sub-conductors fracture failure are caused by the shear fracture of partial aluminum wires due to the shear stress of conductor torsion, as well as the combined effect of dynamic tension formed by ice-shedding and icing static load. Based on the research results, this paper proposed the corresponding measures for the operation, maintenance and reformation, which could provide reference to avoid similar failures.
For the steel tube tower applied in 1 000 kV UHV AC double-circuit transmission line, there were larger deviations between theory and practice calculated results of cross arms stress condition. Based on the ANSYS numerical simulation method, this paper analyzed the structure of cross arm for UHV steel tube tower by using bar and beam element model. Finally, the suggestions were proposed for the structure and design of cross arms, according to the calculated results.
As one of the most commonly used fittings in transmission lines, suspension clamp usually led to unnecessary electromagnetic loss due the unreasonable material selection and structure design, which not only wasted electric energy, but also caused electromagnetic interference on the surrounding environment, This paper carried out the electromagnetic simulation research on the suspension clamp and conductor nearby with three dimensional finite element simulation technology base on ANSYS software, analyzed the related laws of suspension clamps magnetic field and eddy current distribution in AC transmission lines, as well as the electromagnetic loss. Then, the simulation result was compared with the experiment and the accuracy of simulation was verified. The calculation and comparison results on suspension clamps with different materials show that suspension clamp made of aluminum alloy has less electromagnetic loss than the one made of ferromagnetic material. According to the simulation research on suspension clamps with different structures, it is show that the grooving can properly reduce the eddy current density and electromagnetic loss in the appropriate place where the value is abnormal. On the basis of the above analysis, some optimization suggestions were proposed for the decrease of electromagnetic loss.
The objective of relay protection can ensure the safe and stable operation of power grid as far as possible, and the protection configuration schemes have different influence on power grids. This paper analyzed the reasons of protection failure, established the Markov model for the evaluation of relay protection reliability in different schemes and studied its reliability by using state space method. On the basis of the researcher results, this paper further investigated the influence of economic factors, such as cost, fault loss and so on, which could more comprehensively reflect the different effect of configuration schemes and provide references for the analysis and evaluation of protection configuration schemes in practice.
A new current differential protection method of fault component was proposed for high voltage (HV) lines, which was not affected by distributed capacitance current and load current in theory and had high sensitivity and reliability. The presented protection method has achieved a great improvement on the abilities of detecting high resistance ground faults and possesses higher sensitivity and reliability at ground faults with high fault resistance in transmission lines operated in two phases. The simulation results show that the protection method is correct and effective
The protecting mesh between two phase conductors was used to avoid navigation-closure, during the large span stringing cable process for the Yangtze River at Dengjiaxi, which applied old ground wires. In mountain area, the arrangement of corner block and pulling field was suitable for the cable-fitting with low tension. The inversion method of tension wheel could improve the efficiency of stringing construction. The results show that the construction mode of high-tension stringing cable can ensure the cables mechanical and optical property, as well as the normal navigation of the Yangtze River, which has significant social benefit and can be used as references in the similar construction process.
The J2ME technology was applied in the calculation of sag observation angle for overhead lines, and the mobile phone calculation was used in the conductor tightening construction, which could make field application convenient and save the calculation time. The results show that the rational and feasible calculation method and the accurate data can improve the production efficiency and the quality of construction.
Modular design and construction technology are one of the most important features of the 3rd-generation nuclear power plant, and the opening-top construction is the precondition of application of modular technology. Combined with the powerhouse structure and construction characteristics of nuclear power plant project, this paper proposed four kinds of floor structure schemes for opening-top construction, and summarized these floor structure schemes structure characteristics, design points, scope of application, advantage and disadvantage. Finally, the technology conditions of opening-top construction were suggested, which could provide references for the application of opening-top construction technology in nuclear power project.
