By applying high frequency force balance technique on rigid section models in wind tunnel, the models of 2-bundle and 6-bundle D shape iced conductor in 13 different cases were tested. The static aerodynamic coefficients of the models, including the whole aerodynamic characteristic of different initial attack angle and each aerodynamic characteristic of sub-conductor in 60° attack angle, were obtained from 0°～360° by every 5° in wind tunnel test. Then the galloping stability of D shape iced conductor was analyzed based on the Den Hartog criterion. The test results show that the initial attack angle has impact on the aerodynamic characteristic and galloping stability of iced conductor. However, the wake interference around sub-conductors on aerodynamic characteristic is obvious under certain wind attack angles, furthermore, it improves the galloping instability. The obtained test results can provide basic aerodynamic data for the analysis and prevention technology of galloping of 2-bundle and 6-bundle D shape iced conductors.
Timely and accurate information of weakly-damped low-frequency oscillation characteristics is important to the stable operation of system. Ibrahim Time Domain （ITD） and random decrement method were proposed to processing wide area measurement signal and systematically study the oscillation characteristics of power system. Based on the basic principle introduction of this method, the power spectral properties of different types of signals measured in China Southern Power Grid （CSG） were compared, and the definition of ambient signal was presented. Then this approach was applied to the simulation data from the 36-node system and the measured data in CSG, in order to grasp the dynamic characteristics of the interconnected power grid from typical signals, realize the characteristic parameters identification of low-frequency oscillation in power system, which could lay a solid foundation for the timely and accurate grasp of the dynamic characteristics of interconnected power system based on wide area measurement signal.
The structure of transmission tower is an important lifeline project as the carrier of high load power. Structural fatigue damage has been considered as one of the most vital destructive factors in civil engineering. Based on the Miner’s linear fatigue accumulation rule and S-N curve, the fatigue life analysis method for ZSZH tower in the 500 kV Haining-Qiaosi double circuit transmission line was proposed. In the fatigue analysis problem of transmission towers, this method not only emphasizes on wind loads, but also considers several extraordinary serious load cases during the design reference period, including typhoon, ice load, construction load and so on. The numerical simulation results demonstrate that this method is quite accurate and effective to predict fatigue life of the transmission tower, which lays a foundation for further engineering application in the future.
The classification of icing areas is one of the critical steps of the power grid construction. If the design ice thickness is underestimated, power transmission lines may not be able to withstand the influence of accreted ice, which might result in transmission line breaking or even tower collapse. On the other hand, if the design ice thickness is overestimated, the cost of construction, maintenance, and reconstruction may be increased to result in resources waste. With the aim of reasonable classification of icing area for power grid, five classification methods were discussed, including method of experience investigation, method of icing data, method of CRREL model, stepwise regression method of meteorological parameters, and model method of local topology-meteorology influence on icing classification. Finally, the classification steps and application features were discussed.
As the first station of UHV power grid in Fujian, the 500 kV main connection scheme of Fuzhou UHV substation affects the steady and security of local power grid. According to the construction schedule of Fuzhou UHV substation and the characters of Fujian 500 kV power grid, this paper analyzed the 500 kV main electrical connection of Fuzhou UHV substation, from the aspects of network structure, power flow distribution, short-circuit current, economical efficiency and so on. Instead of traditional scheme in which the number of transformer matches the number of 3/2 unit, the recommended scheme for 500 kV main connection of Fuzhou UHV substation is setting up east and west transmission channel respectively. The analysis results show that the recommended scheme combines the actual situation of Fujian power grid, and can efficiently enhance the power transmit thoroughfare of coastal area. The recommended scheme has a better adaptability to the change of future power flow distribution than other schemes, also has the advantages of investment saving, short construction period, convenient operation and maintenance, etc.
Since the 1990s, the reliability of circuit breaker （CB） device increase greatly along with the continuous progress of CB technology, but the technical level of disconnector （DS） has stagnated. So, the new disconnecting circuit breaker （DCB） devices have been applied to the power grid. This paper studied the 110 kV DCB which was applied in Wuhan 110 kV Future City Substation, compared DCB with tradition CB and DS, and introduced the design idea, main characteristics and advantages of DCB. The technical features, application situations, and specific type test requirements of DCB were analyzed, through the research findings of DCB’s foreign application, type test and on-line monitoring status. The research results can provide reference and experience for the application and operation maintenance management of DCB in the new smart substations.
This paper studied the application of artificial standard time history wave on the seismic performance evaluation of 500 kV arrester in shaking table test, in which artificial standard time history wave, EL Centro seismic wave, Taft seismic wave, Beat－Wave were inputted unidirectional or bidirectional. The test results show that, under above 4 kinds of seismic waves with the same seismic grade, the stress of the equipment root under the action of artificial standard time history wave is the largest. The difference of test results for the different equipment under the action of artificial standard time history wave should be relatively small because the dominant frequency segment of the response spectrum of time history waves is gentle, so artificial standard time history wave is applied to the seismic performance evaluation of 500 kV arrester. Comparison results under the action of unidirectional or bidirectional waves demonstrate that it can only carry out unidirectional excitation shaking table test for the seismic performance evaluation of two-dimensional axisymmetric structure.
Downburst is a kind of strong wind that results from the flow downdraft nearby ground in thunderstorm. In order to make the application of downburst wind profiles convenient in engineering design, taking the vertical dash of downburst on horizontal ground as an example, this paper summarized the calculation process of horizontal wind profiles of downburst with using international dimension, and simulated the true scale wind field of downburst with using CFD, Then, different empirical formulas were compared and selected to obtain the engineering calculation method of wind profile. Finally, downburst wind profiles at different radial position were calculated by the chosen emprical formula, as well as the influencing height and radial scale of downburst were analyzed based on the downburst distribution at atmosphere boundary layer, which has shown that the maximum influencial height of downburst is near the position of its maximum wind speed.
Strongly weathered tuff geological condition was encountered under the construction of large crossing towers in the Yuhuan Substation–Yueqing Substation 500 kV double-circuit power transmission line project. Static pullout tests were conducted for nine single anchor foundations and six group anchors foundations. The variation of internal force and strain of anchors were tested and analyzed. Meanwhile, the failure modes and bearing characteristics of the rock anchor foundations were obtained. The experimental results show that the internal force of single anchor increases with the increase of load. The internal force decreases with the increase of buried depth, and reduces to zero beyond certain berried depth. The ultimate pullout capacity of group anchor foundation is not the simple sum of that of single anchor foundation, in which the group anchor effect exists. This study also provides a reference and basis for practical engineering application.
The multi-tripping accidents often occur in 220 kV double-circuit transmission lines under lightning, which has serious influence on the reliability of power system. Firstly, two lightning multi-tripping accidents that happened in Lishui and Ningbo were analyzed. Then, the model with considering grounding resistance, induced voltage component and other factors was built based on EMTP program. The simulation results show that it can realize the accurate reappearance of the four-phase flashover accident caused by the lightning current with-179 kA amplitude in Lishui Xianghe/Xiangmu line, as well as the three-phase flashover accident caused by the lightning current with-140 kA amplitude in Ningbo Xiaochang/Xiaozhou line. The lightning current amplitude and the phase of power frequency voltage can be good match with flashover phases, and their values derived from the model match the real data perfectly. Based on the simulation model, this paper further studied the flashover phase distribution law of multi-tripping accidents in 220 kV double-circuit transmission lines. The results show that the power frequency voltage is the key issue that decides the flashover phases of multi-tripping accidents.
Based on the blocking fault of monopole double valve group in ±800 kV Chusui UHVDC transmission system happened on Dec. 15, 2012, the analysis of on-site equipment checking, relevant recorded wave and protection actions were carried out. It points out that Pole 1 blocking was caused by the asymmetric operation of two groups of Pole 1. Moreover, the mismatch of the grounding lines and the insulation level of the neutral bus resulted in the flashover and imbalance protection action of grounding lines. Finally, this paper also suggests reasonable improvement measures for the exposed problems.
The online line-loss calculation platform with province and region integration uses the CIM model interface and imports grid models directly from the EMS, which does not require building the model manually and repetitively. It can track the changes of the grid model, and ensure the qualified rate of state estimation at a higher level, which can lay the foundation for the accuracy statistics and computation of the loss-loss. The power data provided in the platform can covered all grid models of 110 kV and above, which is the verification and important supplement of power data collection system. Based on this platform, it can provide a more comprehensive analysis platform of network-loss for the staff, and find an effective way to reduce network-loss through the analysis of system loss and equipment loss under various operation modes. The theoretical calculations of line-loss in Hebei South Grid under typical daily load mode have been carried out by using this platform. Through the daily line loss analysis, it can find the problems of online data in the EMS system in time, which can improve the qualified rate of system state estimation.
In order to better solve the technical problems during the selection of anthracite-fired boiler such as ignition, stable combustion and burnout, the configuration and operation performance were analyzed and compared between 600 MW supercritical W shaped flame boiler and supercritical circulating fluidized bed （CFB） boiler combined with practical engineering application. The research results show that, W shaped flame boiler has good combustion performance when burning anthracite, but has higher concentration of NOx at furnace outlet, and high temperature corrosion problems of heating surface cannot be ignored. However, the NOx concentration at furnace outlet is relatively low and the combustion is stable for anthracite-fired CFB boiler, but the burning performance needs to be improved. It is suggested that supercritical CFB boiler should be preferred option for 600 MW anthracite-fired supercritical boilers, and it is necessary to improve the burning performance through reasonable technical way.
Large-scale cascading trip-off of wind turbine has become the new problem during the fast development of wind farm. Aiming at the cascading trip-off failures frequently occurring in Jiuquan wind farm, this paper analyzed the typical development process and time-spatial frame of the failures to find the main reason. Based on this, according to the fluctuation of wind power and the step changes of voltage caused by fixed reactive power compensation switching, the coordination control models and strategies of regional automatic voltage control （AVC） were proposed. Finally, the steady-state voltage analysis was carried out based on the real operation data of Hexi power grid, and the feasibility and effectiveness of the proposed models and strategies were verified through the control effect simulation of ‘2-24’ trip-off failure in Jiuquan.
This paper introduced the Super304H steel tube’s production situation at home and abroad in ultra supercritical units, and analyzed the quality situation of domestic Super304H steel tube including chemical composition； mechanical property； metallographic characteristics. The investigation results show that many manufacturers in China have the production capacity of Super304H steel tube at present. Compared with imported Super304H steel tubes, the domestic ones have difference in some indicators, but have been able to meet the requirements of relevant standards. The domestic Super304H steel tubes have been applied in ultra supercritical units in China, whose operation should be under strengthened supervision.
Taking a 600 MW direct air-cooling unit as an example, the influence of environmental wind on the heat transfer efficiency of air-cooled condenser was numerically simulated by using CFD software （Fluent）, and the schemes of different windshields installed around the air cooling platform were put forward. The calculation results show that the installation of windshield can reduce the influence of hot air recirculation and the ‘intrusion’ phenomenon, as well increase the air flow in air cooling unit and the average heat transfer of condenser, which can be up to 72.52% and 24.51% higher than that without windshield, under 0 m/s-12 m/s environmental wind speed.
The reducing agents for flue gas denitration systems in coal-fired power plants mainly include liquid ammonia, ammonia water and urea. However, the selection of reducing agents in practical project is always a troublesome question. Based on fuzzy comprehensive evaluation method and membership degree principle, the quantitative analysis of evaluation index were carried out for reducing agent, and the evaluation results were obtained according to the principle of maximum membership degree. Then, this paper analyzed the impact of factor weights on the final results according to the actual situation, and obtained the result that liquid ammonia was best. Liquid ammonia, ammonia water and urea all can be used as reducing agent for the SCR denitration system in large units, but liquid ammonia is the best because of its prominent economy characteristics and slightly better technical performance.
In order to realize the effective operation management of distributed electric vehicle's （EV） charging pile, according to the characteristics of EV charging facility and the requirement of users, the operation management mode of distributed EV charging pile was put forward. In combination with the current communication technology, data acquisition technology, GIS technology and Web technology, this paper proposed the construction scheme for the operation management system of EV charging pile, which included data acquisition system, card management system and web geographic information system. Finally, the application situation and future development direction of operation management system were introduced.
At present, the research and development of small distributed photovoltaic （PV） power plants is not mature in China. So this paper proposed a centralized design method for small distributed PV generation system. This paper introduced the selection basis of charging controller and inverter, as well as the design formulas of energy storage battery； described the series-parallel design formula of PV module and the selection method of PV cable according to the electrical characteristics of PV modules； deduced the formula of PV array spacing according to the different layout of PV modules, and determined the layout spacing between each row. Finally, the parametric design of the entire power system was achieved based on the above methods and the specific device parameters.
It leads to information asymmetry and thus affecting smoothly running of generation rights trade in the existing generation rights trading, because of excessively depending on a third trading institution which has difficult to understand and control the power plant operational status of the side selling （buying） generation right. Therefore, this paper designed a new generation trading model to reflect the interest needs of different generation trading side based on the stakeholder theory, which defined the rights of the parties and the order of the transaction implementation path, and resolved the information asymmetry using dynamic game. Then, this paper proposed the bidding strategies that could pursue the both interests to maximize and maintain the equilibrium of long-term game, based on the perspectives of expanding trading range and unifying transaction price. The empirical results show that the generation rights trade mode and its bidding strategy can help both parties to establish a long-term stable cooperative relation, improve the overall social utility, and save operating costs and energy consumption.
