Based on an in-depth analysis of the digital design needs of power grid enterprises and power design enterprises, a digital design technological system was established for promoting the development of digital design technology in China. Rules were formulated for guiding the direction of information construction of power design enterprises so as to realize sharing of design information in the whole life cycle of the power projects and to ensure the certainty, integrity and uniqueness of information. The digital design technology system can be used as platform to improve the labor productivity of design enterprises, ensure the design quality of the finished products, and promote the coordinated development of power transmission & transformation design, power grid construction and management for achieving a win-win situation.
The industry design standard of tower foundation in China, DL/T 5219-2005 “Technical Regulation for Foundation Design of Overhead Transmission Line” is under revision, of which the parameters A1 and A2 in shearing method of tower foundation uplift calculation are specially covered. Based on the analysis of three kinds of theoretical calculation models for typical foundation uplift at home and abroad, the unified calculation model and theoretical formula for the uplift bearing capacity of tower foundation are built, the unified theoretical formula of parameters A1 and A2 for shearing method of foundation uplift calculation at different soil failure plane morphology is presented, as well as the relationship between the values of A1 and A2 and soil failure plane morphology, internal friction angle, the ratio of uplift resistance depth to diameter of foundation slab is analyzed. The research results will provide references for the engineering design of tower foundation and the formulation or revision of relevant technical specifications.
The electric field distribution of UHV AC parallel lines have great influence on enviormental protection, the corridor width and the demolition range. the power-frequency electric field strength of 500～1 000 kV single-circuit and double-circuit AC lines under various conditions, such as different phase sequence, line heights and distances are studied in this paper, and then the distribution rule of electric field in 1 000 kV UHV AC parallel lines is obtained. Finally, the phase arrangement and the corresponding line space are proposed on the basis of the existing environmental standards, which could provide support for the construction and operation of UHV AC power transmission projects.
Gravel soil is one of the special ground in Xinjiang Gobi area. In order to give full play to its good engineering mechanics properties, dredged foundation is usually used for transmission line foundation engineering in this area. Aimed at the selection and design problems of dredged foundation for transmission tower in Xinjiang Gobi area, the foundations applicability in this area is studied through the analysis of the load test results of dredged foundation in several gravel soil sites, based on the characteristics of dredged foundation and gravel soil in Gobi area. Stability analysis methods and design conditions of dredged foundation are proposed, which have been applied in the supported project of Xinjiang area and have achieved good economic and social benefits. The design and application of dredged foundation show that the foundation is suitable for the transmission line projects at different voltage level in Xinjiang, which can play good shear behavior of gravel soil foundation, thus having a good prospect of popularization and application.
Taking Chengde-Pingancheng 500 kV double-circuit line project and Ningdong-Shandong ±660kV DC power transmission line project as examples, in this paper, the 45° wind load on tension towers is calculated and the wind loads in different angles are compared. The internal force increase of tower legs and the influence on tower weight under 45° wind conditions are also analyzed, based on the comparison with 90° wind conditions. It was suggested that 45° wind should be considered as unnecessary condition for the design of tension tower of EHV transmission lines.
According to the importance of the safe operation of high-speed railway, in this paper the status of power transmission lines crossing high-speed railway and the selection of spanning mode are analyzed. The design technologies of transmission lines are specially discussed in order to make design scheme meet the technical requirements of transmission lines crossing high-speed railway, which could ensure its safety and reliability.
The transient rated calculation of AC filters in converter station is used to choose the suitable arresters for protecting the reactors and resistors in filter, also for determining the insulation levels and transient impulse currents of the devices in AC filters. Taking ±800 kV Jinping Sunan UHV DC Power Transmission Project as an example, the calculation methods of transient rating for AC filters are introduced in detail, including the schemes of arrester choosing, the determination principle of insulation levels for AC filters components (capacitance, reactance, resistance, etc.), as well as the calculation method of transient voltages and currents for other important parameters determination. The methods and parameters introduced are the important references for equipment selection, such as capacitors, reactors, resistors, arresters and current transformers in AC filters in HVDC power transmission project.
Multi-location comparison is needed when towers have to be installed in the river floodplains for UHV transmission lines. The surface water modeling system (SMS) is used to analyze the flow field distribution on the floodplain under design flood, based on which the towers location for large-span transmission lines are selected and assessed. The calculation results of SMS are direct, reasonable and can provide a good basis for choosing the tower locations in floodplain where the flow is small, the scouring depth is small and the tower has little impact on flood passage.
Frost-heaving is the key factor that impacts the stability of foundation in the frozen-soil region. In this paper, the conventional anti-frost heaving measures are improved by six treatment measures, such as cone cylindrical foundation, the replacement of heaving material, lubricant smearing and the application of glass steel formwork. These measures have been proved reasonable and effective through engineering practices.
This paper introduces the distribution of karst in Guangdong and the basic situation of geological disasters of karst collapse. By analyzing and studying the disaster cases of karst collapse which have occurred in Guangdong in recent years, the various induced factors of karst collapse are also theoretically analyzed, such as hydrological factors, surface water erosion, reservoir impounding, groundwater pumping, vibration effect, load function. Then, two main genetic mechanisms of karst land collapse: suffusion theory and vacuum erosion theory are discussed. Through field investigation and references of previous research results, it shows that the karst land collapse has been formed based on the suffusion theory in most areas of Guangdong. Based on the above analysis and the characteristics of power grid system, the evaluation method of transmission lines in karst collapse areas is proposed. Moreover, the stability of transmission tower in collapse areas by using numerical simulation method is investigated to get the results in accordance with the reality, which proves that the method could be promoted.
UHV transmission line is long, so the secondary arc is hard to quench. If single-phase automatic reclosing fails, system security and stability will be impacted. Therefore, it is necessary to study the secondary arc current for UHV transmission lines. Taking 1 000 kV transmission lines from Nanyang to Jingmen as the research object, the simulation model is established in this paper to calculate the length of transmission lines, the fault location and the influence of arc resistance on secondary arc current, by applying ATP-EMTP. Finally, the application effect of two methods of extinguishing secondary arc current, high speed grounding switch and shunt reactors with neutral reactor, are compared for the EHV and UHV transmission lines with shunt reactor.
The upgrading improvement by using augmented capacity conductor could alleviate the insufficient capacity problem of transmission lines. In spite of the significant capacity increase, the maximum temperature of conductors will exceed 80℃, thus it is inappropriate to use the sag calculated in the condition of 40℃, 50℃ or icing without wind to locate towers. The calculation method of location sag when using augmented capacity conductor is analyzed, and the verification according to examples is carried out.
Process level is one of the important characteristics of smart substation, which is different from conventional substation. Its networking scheme directly affects the realization of protection and control function and the investment of network equipments. Based on the analysis and comparison of several kinds of typical process-level network topological structures and sampling value transmission protocols, a suitable process-level network scheme for smart substation is suggested in this paper. Combined with the current situation of substations, the design examples are also presented in aspects of equipment selection and functional requirements.
A new fault location function based on distributed parameter line model is generated, which takes the influences of shunt capacitance into consideration. The method is immune to the influence of shunt capacitance with distributed parameters modeling for two-terminal transmission line, and is not disturbed by fault resistance and load current. The simulation results by PSCAD /EMTDC show that the proposed method is correct and validity.
Wind vibration coefficient is one of the key factors for wind-resistant design of cooling tower, at present, the wind vibration coefficients given by Chinese cooling tower design codes are only associated with terrain roughness, but ignoring the effect of structure dynamic characteristics which are closely related with them. This paper use Consistent Coupling Method-CCM to get the values and distributions of wind vibration coefficients of three different hyperbolic cooling towers with similar shape ratio but different heights, the results shows that: the wind-induced response of cooling towers are closely associated with their heights, and the usual correspondence of Unified value to different cooling towers with different heights is worth deliberate. This conclusion may provide some performances to structure design and research on wind-resistant reliability of cooling tower.
In order to solve the problem that the primary or both the primary and the backup multiple function processor (MFP) modules were offline simultaneously in the DCS of 300 MW units in Shaoguan Power Plant, with the analysis of the communication between the primary and backup MFP modules and the prefabricated cable, the cause of MFP module fault was found. After proving the compatibility of BRC-300 controller and MFP module, 10 pairs among the 29 pairs of MFP modules were promoted to BRC-300 controller; the configuration software in the control system was also promoted. Then, the integrity of BRC-300 controller configuration was checked. Meanwhile, the daughter board chip of network processing module was upgraded to avoid the interruption of data transmission between BRC-300 controller and other MFP modules. The good communication between BRC-300 controller and MFP modules could be realized by using control channel bus. Finally, the correctness of the design scheme was proved by the actual operation, thoroughly solving the offline problem of redundant MFP modules, as well as ensuring the safe operation of units.
The No.1 and No.2 units in Yuncheng Power Generation Company are 600 MW air cooling units, the turbine efficiency of which had been far lower than the design value since operation. A series of measures of efficiency increase and consumption reduction were adopted to improve the units efficiency, such as the reformation of steam seal, the treatment of inner leakage in steam valve, the optimization of control valves characteristic curves and sliding pressure curves, the optimization of sequence valve control for high pressure control valve. After the implementation of these measures, the economy of the units has been greatly improved in low load condition, while the throttling loss of high pressure control valve has been obviously reduced in high load condition so that the efficiency of high pressure cylinder has been increased. According to the electricity generation of Yuncheng Power Generation Company in 2010, the economic benefits obtained from the treatment have exceeded 10 million yuan.
Aimed at the problems of slag leakage, cracking, abrasion, etc., the technical retrofit of slag discharge system was implemented for the 300 MW circulating fluidized bed boiler (CFBB) in Xukuang Power Plant, which included the substitution of improved circular metal corrugation compensator for expansion joint, setting supporting structure at the joint of slag inlet pipe and furnace, setting wear-resisting structure at the target area of expansion joint of slag inlet pipe, setting wear-resisting box at upper and lower elbow of slag inlet pipe. Through the retrofit, the equipments service life could be prolonged, the maintenance cost could be reduced, and the safety coefficient of long period stable operation could be improved.
In order to improve the operation reliability and stability of 1 000 MW generators, as well as prevent the excitation system from the abnormal away, which may lead to the wrong tripping operation of generator protection, the matching between the setting value of generators field loss protection and the limiter parameters of low excitation in excitation regulator, the matching between the setting value of generators over excitation protection and the limit parameters of voltage/frequency in excitation regulator, as well as the matching between the over current protection of generator stator and the limit parameters of stator current in excitation regulator are analyzed in this paper, on the basis of engineering examples.
Three 1 000 kV circuit breakers are added to the expansion project of Jingmen UHV substation. Hybrid gas insulated switchgear (HGIS) is applied that the arrangement of 1 000 kV main wiring was changed from double breaker transition connection to 3/2 circuit breaker connection. With the construction characteristics of Jingmen substation expansion project concerned, “2+1” and “3+0” layout mode of 1 000kV HGIS are analyzed. The uneven settlement problem of HGIS foundation under the “3+0” mode is studied. Then, the uneven settlements in early and late stage are both calculated. Finally, it is suggest that the compensation units of anti-sedimentation telescopic corrugated pipe should be added in order to ensure the safe operation of the equipment.
The winding arrangement is studied for the UHV converter transformer, whose line side winding connected 1 000 kV AC and rated voltage at DC side was ±1 100 kV DC. Through analyzing the advantages and disadvantages of different main insulation structure schemes, the scheme is recommended. Moreover, the electric field calculation for its main insulation structure is carried out, which shows that the recommended insulation structure arrangement is reasonable, and the insulation margin can meet the engineering requirements.
In the bill-of-quantity model, as there are some differences between bidding engineering quantity and completed engineering quantity, the unbalanced quotation adopted by bidding companies may lead to the probable risk to construction companies. Based on the thorough analysis on the bidding strategies of bidding companies, the optimal unbalanced bidding model was built to acquire the optimum price quotation. Then, with Monte Carlo simulation method, cost risk evaluation model of power transmission and transformation projects was built to meature the risk of construction companies. The appropriate measures were used according to the risk scale, which could minimize the happening of excess budgetary estimate. The research results have guiding significance to the engineering cost management, and will standardize the bidding rules for the health, reasonable and sustainable development of the construction of power transmission and transformation projects.
Based on the introduction of multiple lightning tripping accidents and the cause analysis of tripping for 110 kV Longgao 898 transmission lines, the fault point of C-phase arrester on the 35# large crossing tower over the Yangtze River is pointed out in this paper. The adjustment scheme of line lightning protection, which was to restore the overhead grounding wires, was put forward combined with the site situation. The results show that the transmission line after the adjustment run normally. Therefore, it is suggested that the arrester monitoring in transmission lines management should be strengthened.
Huxi Substation Foundation Project is featured by many pile types, a number of piles, being close to an operating substation, complicated process and long duration. This paper discussed in detail the necessity of pile foundation construction monitoring, monitoring items, monitoring requirements, the actual records of monitoring and the corresponding control measures, as well as described the monitoring items such as excess pore water pressure, deep soil displacement and pile top displacement and ground displacement, which could provide guidance to the pile construction.
Based on oversea successful experience in the modular construction technology of raft foundation reinforcement cage (RFRC) for reactor building in nuclear power plants, this modular construction technology for the reactor building in CPR1000 nuclear power plant is studied. Through the comparison and comprehensive evaluation of four kinds of modular design schemes of RFRC, a recommended scheme is proposed, and a special spreader was researched and developed for the RFRC modular construction. Furthermore, the RFRC modular construction scheme of a demonstrative project which will adopt the RFRC modular construction technology is studied, including the selection of cranes for lifting modules and crane positioning, construction site requirement for modular construction. The research results would lay a technological foundation for the all-round implementation of RFRC modular construction in nuclear power plants in China.
