The annual-value cost-benefit analysis on different distributed energy resources (DER) reflects the overall investment and efficiency of microgrids, which provides a reference for the selection of microgrid programs. The improved analytic hierarchy process (AHP) is proposed to evaluate the cost-benefit of microgrids from both objective and subjective, which adoptes three-mark method to construct the judgment matrix in order to improve the convergence rate and consistency, normalizes the mean of the weight vectors in order to avoid the differentiation of judgment matrixes constructed by experts, and comprehensively considers the cost of the DER, as well as the influence on the environment and different kinds of loads, in order to quantify each index value of microgrid’s cost and benefit. The cost-benefit evaluation of four microgrid schemes shows that the combination of wind turbines and battery can achieve better economic effect in microgrid area. The research results have verified the feasibility of AHP.
Aimed at some power quality problems caused by nonlinear load shock, such as voltage sag, major harmonic wave, low power factor, a pseudo linearization feedback control method for three-phase voltage source converter (VSC) based on superconducting magnetic energy storage (SMES) technology is proposed in this paper. Due to the use of inverse system in three-phase converter VSC mathematical model, the complete decoupling between DC capacity voltage and reactive current is achieved, and the pseudo linearization system is constructed. The regulation and control system of chopper current is designed which could give full play to the endurance ability of SMES. The inner current loop controller is also design to solve the power quality problems and carry out the optimal setting of VSC capacity.
Galloping of conductor with thin ice accretions is a common but unexplained phenomenon. Wind tunnel tests are needed to study the aerodynamic characteristics of conductors with thin ice accretions. Based on the galloping investigation of real transmission lines with ice, three conductor models with different ice thickness are designed and tested in the wind tunnel. The average aerodynamics of quasi-oval shape iced conductor models in two different flow fields are measured by using six-component high-frequency balance. Through the comparison and analysis of average aerodynamic coefficients, Den Hartog coefficient is found not suitable for the analysis on thin ice wire. On the basis of qualitative explanation of Den Hartog to galloping, two necessary conditions of galloping are proposed. Through the analysis of test results, the wind attack angle has been acquired when the conductor gallops with thin ice accretions.
Because there is no uniform evaluation standard for DC interconnection project, combined with the characteristics of the project’s investment, construction and operation, the evaluation index system of success degree for DC interconnection project is built in this paper from six aspects: the process evaluation, the economic evaluation, the impact evaluation, the management evaluation, the technology evaluation and the target evaluation. In view of the multiple levels of the index system, the success degree at each level is recognized by fuzzy recognition method. Finally, the feasibility of multi-level fuzzy recognition model is analyzed and verified by examples. The index system and the evaluation model have the certain reference value for the objective and accurate evaluation of success degree of DC interconnection project.
Aimed to a 500 kV power transmission line project, considering the design wind velocity increase (about 35 m/s) in micro-topography or microclimate region, the modal analysis, dynamic time-history analysis and static analysis are carried out on the cup-type power transmission tower with or without viscoelastic damper (VED), respectively. The results show that the natural vibration period of the tower increases by 14.3% after using VED; the wind vibration coefficient first increases, then decreases, with the maximum value of 28.1% appearing at the tower cross arm; the pressure of main material deduces about 14%; the calculated tower weight reduces about 5%. Therefore, the vibration control effect of VED is obvious.
The series compensation platform is composed of foundation and short column, vertical support insulator, diagonal tension insulator, steel platform and series compensation equipments. The structure characteristics of series compensation platform are introduced in this paper, and nonlinear finite element model for the series compensation platform structure is built based on a real project. In the modeling process, the nonlinear characteristics of diagonal tension insulator are considered, the static calculation is carried out and earthquake action is analyzed, which could provide a theory basis for the structure design of series compensation platform.
Integrated grid operation smart system will be built in Hainan grid during the “12th five-year” plan period, in which new demands for dispatching data network have been put forward with the business characteristics. The business needs of intelligent system of integration grid operation and the building features of dispatching data network are analyzed in this paper. Then, the network topology and routing strategy design are discussed from some aspects: network extension, business support, three-layer network function, bandwidth utilization and so on, taking the construction of power dispatching data network in Hainan as an example. Finally, a preliminary construction scheme of Hainan power dispatching data network is proposed, which could take account of various business transmission flow and have a certain reference to the power data network under new business conditions.
The concrete damage of 11 substations are investigated in industrial pollution or carbonization area, self weight collapse loess area, dry-wet cycling area, freeze-thaw cycles area or saline soil erosion area of Guizhou Province, and the technical indices of concrete durability are obtained through tests and analysis. The results show that both the concentration of metal ion and nonmetallic ion in foundation soil and groundwater exceed standards in different degrees, which have serious impact on the service life of concrete engineering, presenting as the phenomena of crack, sapling or damage on concrete surface, from the point of macroscopic view. According to the different geological conditions, some relevant prevention and remedial measures are proposed. The research results can provide theory basis and technical support for the evaluation of concrete durability of substations under alpine environment condition in Gansu Province.
In recent years, the power grid failure caused by lightning has kept on a high level. Many kinds of lightning protection device can’t be used in all lines because of the l cost limit and protection scope. Areal-time monitoring and analysis system for grid lightning has been developed based on the wireless sensor network, which could arrange the wireless sensor node according to the line’s conditions,collect real-time status data of front arrester and the parameters of lightning, and sent them to master monitoring center through the multi-jump sensor network. Then the workers can timely master the operation status of grid lightning protection equipments, as well as can analyze the lightning form and fault position, which will provide the powerful evidence for the accurate judgment of lightning disturbance causes to transmission line.
The features and advantages of optical transport network (OTN) technology is discussed in this paper. Taking power network in Hubei Province as an example, the status and characteristics of OTN in power system are analyzed, and a new technology was introduced to further optimize the existing network structure. The original synchronous digital hierarchy (SDH) transmission system is replaced by the new OTN system in provincial main power transmission network, which could improve the bandwidth and safety of the network, meet the needs of smart grid and operation management, as well as ensure the reliable and efficient transmission of business information.
For the large-scale photovoltaic power station, the cost of collecting power line has a large proportion and the electric energy loss is high due to the high generation price of photovoltaic power, so the selection of economic section is important for collecting power line. Because of the change of technology and economy and the limit of application condition, the economic current density curve in existing electrical rule or code can not satisfy the selection of economic section for collecting power lines. Through parameter updating, the economic current density is calculated, which could provide references for the design of photovoltaic power station.
The EDPF-NT + DCS configuration auto (EDPF-NT+DCS CA) technology is the latest research achievements of Beijing Guodian Zhishen Control Technology Co., Ltd. in thermal power control field, which fills the technology gap in automation configuration of distributed control system (DCS) in China and abroad. Based on a 1 000 MW unit, this paper introduces the design standard of EDPF-NT+DCS and the EDPF-NT+DCS CA technology from some aspects: configuration solution of I/O database, SAMA control sheet, man-machine interface, and so on. At present, this technology has been successfully applied in some 1 000 MW units in China.
In order to study the reason of frequent pipe burst of heating surface in a 600 MW supercritical W-flame boiler, the numerical simulation of combustion process in boiler is carried out to study the impact of air distribution modes on pipe burst of boiler heating surface. The results show that the temperature field at furnace center is in W shape distribution and symmetric under actual operation conditions. The change of temperature field is not sensitive in the furnace when the ratios of primary air and inside secondary air are 5/6 and 6/5 in front and back arch, and the temperature flame doesn't sweep over the heating surface; however, when the ratios of outside secondary air in front and rear arch and the graded wind in front and back wall are 5/6 and 6/5, the furnace temperature field appears skew, and the temperature flame badly sweeps over the cold ash hopper, which may cause pipe burst of heating surface at cold ash hopper.
The leakage accident of T2 internally ribbed tube in the middle part of spiral water wall in a 660 MW supercritical units was is analyzed by means of macro examination, chemical composition analysis, mechanical property tests, metallographic examination and scanning electron microscope. The results show that the leakage of T2 internally ribbed tube is due to the linear crack caused by improper hot rolling process of tube billet and the manufacturing defects of tube billet. So it should strengthen the surface quality inspection of hot rolled tube billet in manufactory; the inspection for the same batch of T2 internally ribbed tubes should be cairried out timely to eliminate similar defects in power plant.
According to the quality of municipal reclaimed water, the cascade water principle is implemented in Guodian Changcun No.1 Cogeneration Power Plant to improve the water reuse rate, and the waste water reduction technology that waste water during desulfurization process being sprayed into boiler flue to evaporate, has been applied to achieve zero water emission in the whole plant. The design of zero water emission in power plant adopts the technologies as follows: the circulated water used bypass lime treatment system, whose effluent is preferred for boiler makeup water, the rest is back to the circulated water system; the boiler makeup water treatment system uses integrated membrane treatment technology which adapted to the concentrated reclaimed water and could significantly reduced the amount of waste water; Ⅰ reverse osmosis concentrate and pulp of lime treatment system are sent to the flue gas desulfurization system for repeated use. In the zero water emission mode, there were many types of makeup water in the flue gas desulfurization system and the water quality is complicated. So the choose of repeated application should be determined according to the water quality condition. Meanwhile, in the zero water emission system higher requirements are imposed towater management of power plant.
With the increasing unit capacity in power plant, 6 kV auxiliary power system is more and more important for the stable and safe operation of units, especially its quick switching device. Now the new generating units commonly have used quick switching device. In this situation, a number of old power plants also begin to transform auxiliary power system from automatic input device to quick switching device. Taking the MFC-2000 quick switching device of No.5 unit in Douhe Power Plant as an example, the transformation process of quick switching device in 6 kV auxiliary power system and its actual effect after transformation are discussed, which could provide valuable experience for the following work.
Through the analysis on no-bypass desulphurization system of 1 000 MW units in Qinbei Power Plant phase Ⅲ project, the necessity of pre-washing treatment system for wet flue gas desulfurization system is deomonstrated, as well as the process, design principles, equipment selection and the practical application of pre-washing treatment system are introduced in this paper. It has been proved that the pre-washing treatment system exerts good effect in oil pollution and dust control, as well as preventing high-temperature flue gas entering the desulfurization system.
Aimed at the configuration of condensers in the nuclear power plant in the coastal area in China, in this paper the thermodynamic characteristics between single and double backpressure condensers are compared to make an analysisof their technical and economic characteristics. The results show that double backpressure condenser has better thermodynamic characteristics while lacks application experience. Single backpressure condenser is better to be used in the coastal nuclear power plant with low temperature cooling water. However, when the temperature of cooling water is higher than 21 ℃, single and double backpressure condensers should be choosed according to the results of their technical and economic analysis. In the technical and economic analysis process, the risk of using dual pressure condensers should be considered.
Along with the construction and promotion of “12th Five-Year” overall development strategy of State Grid Corporation of China, the role of technological innovation supports has been increasingly prominent. So the management and control system should be improved to comprehensively guide the application and promotion of new technology. In this paper the status, objectives, ideas and achievements of the current management of new grid technology are expounded, and the new technology management and control system for the SG development is built from three aspects: organization guarantee, system construction and technological supports. Through the construction of new technology management and control system for the Corporation, the standardization, process and integration management for the promotion and application of new technology; as well as the sharing and utilization of information resources in a wider range will be realized; and the management efficiency of the new technology application will be improved.
Through harmonic impedance scanning and EMTDC simulation of AC system, the reason why the second-harmonic voltage, generated by the main transformers charging in the northwest power grid, was amplified in Chaidamu converter station is analyzed in this paper. Then some countermeasures are put forward to inhibit the inrush current during transformer switching-in. In order to reduce the impact of secondharmonic on the operation of DC system, based on the equipments’ harmonic tolerance capacity in DC system, the DC harmonic protection under the security and stability condition of AC system is optimized, which has been applied to the Qinghai-Tibet Project. The optimized harmonic protection can improve the adaptability of Qinghai-Tibet DC Project to the weak AC system, and reduce the forced outage rate of DC system.
During the charging test on pole 1 lower-voltage converter transformer in Tongli Station of ±800 kV UHVDC project from Jinping to Sunan, when the reactive power control system gave a filter input command as converter transformer charging, twelve groups of AC filters in hot standby state were connected one by one. Then an over-voltage protection trip occurred at AC busbar, but the control system was automatically input again. The reason is that the voltage of 500 kV AC busbar used for reactive power control is less than the setting value of low voltage monitoring for Ac system (Umax), so the reactive power control continue gives a command to input filter. The above problems caused by measurement circuit fault are solved by adding the low-voltage limited function, and the interlock function is added in AC filter control program, in order to prohibit the AC filter connecting again when it is disconnected while its discharge is not finished. The tests on site prove the change of software is correct and reliable.
In order to analyze the security of tubular bus in earthquake, taking the supported tubular bus structure in 220 kV substation as a research object, the vibration response characteristics of the structure under different seismic intensity are studied, and the principal stress at key position is calculated, by using the finite element model and time-history method. The analysis results show that the first ten natural frequencies of supported bus structure are 1～3 Hz, which are in the predominant period of seismic wave and are prone to resonance during earthquake in its structure. The maximum moment of post insulators happens at its bottom, which makes it easily to be broken. If the seismic intensity is less than or equal to 7 degree, the whole structure is safe because the tensile stress of post insulators is less than the ultimate strength of ceramic. However, if the seismic intensity is equal to or greater than 8, there will be fracture with some post insulators due to the exceeded stress, which may make the structure in danger.
The jumper arrangement in UHV double-circuit transmission lines is more complex, because of the bigger electrical clearance and longer insulator string. By arranging auxiliary tower between two main towers, and rounding the soft jumper from tower inside, jumper exchanged from top to bottom to realize the line transposition in three-pole-composite transposition strain tower. This jumper connecting is simple and clear, which makes the design, construction and operation more convenient, and also makes the overall performance more safety and reliable. The method of separating line-hanging, canceling tower cross arm and optimizing the jumper layout can effectively reduce the size and height, ameliorate the endured force, and improve the structural reliabilities of three-pole-composite strain tower. The weight of three-pole-composite transposition strain tower decreases by 23.4% than that of normal double-circuit transposition tower.
The characteristics of single phase grounding fault in large-scale wind farm and the work principles of multi-tap adjustable arc suppression coil, partial magnetic arc suppression coil and SCR arc suppression coil are introduced, as well as the advantages of dynamic compensation technology and its application in arc suppression of single phase grounding fault in large-scale wind farm are discussed in this paper. Combined with the design and operating experiences of wind power, the main electrical wiring in booster station and equipment selection are optimized by using three-winding transformers and 35 kV neutral point grounding via arc suppression coil. The field test results show that this scheme is beneficial to the safe and stable operation of wind farms.
