Along with the development of strong and smart grid, smart power electronic devices and technologies have been widely used in the smart grid. However, the nonlinear characteristics of power electronic devices brought to the harmonic pollution of smart grid. Shunt active power filter (SAPF) is widely used for the harmonic suppression and reactive power compensation, which has good dynamic compensation in the harmonic and reactive power in the smart grid. This paper analyzed the compensation principle of SAPF, used the ip-iq method including DC voltage loop control for the detection of smart grid command current and the definite-hysteresis current control method for the SAPF tracking control, as well as built the simulation model with Matlab/Simulink from different controlling angle. The simulation results and FFT analysis shows that definite-hysteresis current tracking control is effective for the real-time tracking control, the simulation model system can real-time detect the operation command contained in the current system, and do the effective compensation, which can achieve the ideal effect.
Wind power has the characteristics of randomness and fluctuation. In order to reduce the bad influence of wind power fluctuation on the power grid, as well as variation of wind power fluctuation per minute, the smoothing control was usded for the wind power with a first order low pass filter and battery energy storage system. The suitable smoothing time constant was selected according to the smoothing effect of the wind power, the relationship between energy storage capacity and smoothing time constants was analyzed, and the suitable smoothing time constant of energy storage was chosen according to the smoothing rate of energy storage, which could provide the reference for the wind power smoothing control of wind farm with energy storage system.
The converters in DC transmission project can produce the large number of harmonics which may have harmful effect on the power system stability and the communication lines. In order to effectively reduce the converter harmonics hazards and improve the system reliability, this paper analyzed the time-frequency domain characteristics of converter harmonics in ± 800 kV UHV DC transmission project. According to the relationship between the converter harmonic current，the system operating power and the DC current value in transmission project, the harmonic current distortion rate was presented as the eigenvalues of current harmonic characteristics. Based on the operation characteristics of transmission project, the change law of harmonic current with the increase of transmission power and DC current could be effectively characterized by the harmonic current distortion rate. The study results can provide the theoretical basis for the analysis on converter harmonic characteristics in DC converter stations, as well as the theoretical guidance for the harmonic treatment in subsequent projects and the filter design optimization.
In recent years, in order to reduce shielding failure of tension tower in 500 kV compact transmission line, jumper structure with bypass shielding wires is mounted on the tension tower. This leads to several single-phase grounding faults caused by the falling of bypass shielding wire onto the conductors. The faults reasons were analyzed from the aspects of the mechanical model and T-connection fittings. Several measures were proposed to improve operating security of the line, such as applying performed helical T-connection fittings, optimizing the installing position, length, sag of bypass shielding wire, and so on.
For the Ximeng-Beijing east section of 1 000 kV Ximeng-Nanjing ultra high voltage transmission line, this paper calculated the electric unbalance degree and best transposition position of the mixed transmission line with single-circuit and double-circuit on same tower based on ATP-EMTP. The results shows that the best transposition point is not the 1/3 or 2/3 equal position of lines. Basing on electric unbalance degree, this paper recommends that the lines has a full transposition in single-circuit sections without transposition in double-circuit sections with negative phase sequence, and two transposition towers are located at 63.14 and 103.13 km.
Partial least squares regression (PLSR) is used to load forecasting with considering several related factors, and it has a strong ability to explain the forecasting model. Because it selects the principal components of the independent variable set which are related to the load, and it overcomes the negative influence of the multiple relativity between the independent variables on the load modeling. But PLSR also has some weakness, such as there is useless orthogonal information between the independent variables and dependent variables, which may decrease the model’s forecasting accuracy. Based on the characteristics of PLSR and BP neural network, a PLSR-BP neural network was established, which could modified the weight and regression coefficient in original PLSR model. The practical example result shows that this method is correct and effective.
Based on an actual slope engineering for slope-side foundations of transmission tower, this paper calculated the safety factor of slope by strength reduction method, studied the impact of slope angle, buried depth and top distance on the slope stability, as well as the slope stability’s sensitivity to these influence parameters by the grey relation analysis. The result shows that the size order of influence on slope’s safety factor is top distance >slope angle>buried depth.
Based on the principle of constant length, the state equation of hard jumper system was derived by presetting the sag of the hard jumper’s soft part. Subsequently, according to the inclined parabola theory and 3D space technique, the calculation methods of 3D trajectory and electrical distance of the jumper were put forward, of which the feasibility and reliability were verified by an engineering example.
Combined with the Anxin 220 kV substation project in Baoding, this paper studied on the influence of high submerged depths on substations. The design concept of flood control for substations was put forward which was permitting the flood go into the substation and building the higher electrical equipment foundation than water level. This design concept has realistic guiding significance to the flood control of the substations in the areas that is short of earthwork and has high submerged depths.
According to the excessive vibration of the air-cooling fan bridge in a power plant, this paper analyzed the main reasons of the fan bridge’s vibration and put forward different improvement schemes, whose field tests had been carried out. The test results show that the fan bridge vibration can be significantly reduced by changing the natural frequency of the fan bridge and the fan blade numbers. The research results can provide references for the engineering design and the vibration analysis of the air-cooling fan bridge.
This paper introduced some common problems in the process of electric start-up test for large units, such as operational problems, equipment matching problems, design problems and installation problems. The causes and solving measures of these different problems were analyzed. The result shows that all these problems occurred in the electric start-up test are regular. We should summarize the rules and learn lessons from these site problems, and adopt different prevention and treatment methods to prevent similar problems.
The theoretical feasibility and safety analysis were investigated for the 660 MW supercritical unit, combined with the actual situation of equipment installation in power plants. The designs of flue gas system, start-up system, steam-water system and drainage system were optimized. The trial operation results show that all indexes of units have achieved good results, and the optimization designs have reached the purpose of improving the unit operation’s stability and economy.
Based on a 2×660 MW supercritical power plant in India, this paper analyzed the main technical features of three turbine manufactory in china (Shanghai steam turbine Co., Ltd., Dong Fang steam turbine works and Harbin steam turbine factory), combined with the Power Plant Design Guidelines (2010) formulated by India Central Electricity Authority Regulations. Through the technical & economical comparison of condense back pressure, the results show that the 600 MW class unit in India is base load in the grid, and the back pressure of condenser design as 9.5 kPa is better than 10.13 kPa. The research results can possesses reference meaning for the future design consultation project in India.
The pedestal design of steam turbine is one of the key works in the structural design of power plant. In the pedestal design process for one 660 MW steam turbine in China, the comparative analysis was investigated by building the solid finite element model with Ansys and the discrete model with Sap 2000, in order to ensure design quality. This paper presented the suitable structure of the pedestal with good dynamic characteristics for this steam turbine, which could be a reference for the design of similar units.
Based on the influence studies of the water conditions on the forming mechanism of oxide skin, this paper discussed the formation mechanism and influence factors of the oxide skin in (ultra) supercritical boiler, as well as prospected the research direction of the oxide skin.
This paper introduced the heating surface purging process during the installation of the supercritical once-through boiler in Huaneng Dongfang Power Plant. The comparison of pipe-blowing date and effect between same type units was investigated. The result shows that the heating surface pre-purge during the installation process is worth popularizing, because it can significantly reduce the boiler’s ignition time and pipe-blowing time, as well as save fuel, desalting water, electricity, the way is worth promotion.
Through coagulation clarification test, dynamic simulation test and electrochemical corrosion test, this paper studied the feasibility and control technology of circulating cooling water system for auxiliary equipment in power plant, which used the mixture of circulating water drainage and reclaimed water. The research results could provide a new method and basis for the Water saving work in thermal power plants.
With the development of construction and increase of investment for the power grid in China, the cost control and evaluation has become increasingly prominent role. Because of the application of new technologies and the complexity and diversity of technical schemes, the traditional construction cost index for the transmission line could not fully and accurately reflect the projects’ cost level. Based on the kernel function in support vector machine (SVM) and principal component analysis (PCA), this paper presented a relative cost index for the line projects and built a evaluation index model that was solved by the Matlab 7.0. The validation result of data sample in the 220 kV transmission line project shows that the relative cost index of line project is more comprehensive and reasonable than the traditional index. The relative cost index is convenient to get the comparison, sorting and evaluation of the cost control level for the transmission line projects, which has some maneuverability and application value.
During the construction management of 500 kV Hainan interconnecting submarine cable project, the project standardized management system has been built up by the implementation of procedure and formatting management system and the establishment of information acquisition and communication mechanism. This project standardization management experience can provide references for other foreign power transmission project.
According to the standard, the strain clamp with cracking failure on 500 kV DC transmission line was investigated by the means of macroscopic examination，measured on the margins，ray inspection，chemical analysis and field test. The results show that the main reason of cracking failure is the improper process of pressure contact technique, which presents references for the strain clamp’s hydraulic construction and has significance meaning for the safe operation of transmission lines.
The locating scriber and auxiliary positioning device of crimping angle was developed and applied in order to ensure the accuracy of crimping angle of strained drainage tube in transmission line. This paper introduced the he components and the working principle of locating scriber and auxiliary positioning device. The results of engineering application show that the development of locating scriber and auxiliary positioning device can produce good economic and social benefits. This paper suggested that angle line procedure should be increased in the strained tube processing for the convenient construction.
Based on th creep test between five kinds of conductor with large section ratio of aluminum-steel, the creep curves of five aluminum-cable steel-reinforced (ACSR) wires were drawn, whose aluminum-steel ratios were 11.34-14.47. According to the value of creep deformation, this paper calculated the value of conductor’s temperature drop, and suggested that the value of temperature drop should be 25 ℃ when the aluminum-steel ratios were 11.34-14.47, which could provide references for the construction and design of the transmission line.
The gravity base structure are divided into two categories, concrete caisson structure and gravity base, both of which need using high strength chemical paste for grouting in the installation process, in order to maintain the stability and security of the base structure in the later operation. Based on the structural characteristics and adaptability of the gravity base, the grouting technology of gravity base was investigated, as well as the construction steps of gravity base. The gravity basis structure generally require twice grouting for the safe and stable operation, the first grouting is between the ground and foundation, the second grouting is in the joints of the tower and foundation.
In order to solve the transportation difficulties in 1 000 kV UHV AC transmission engineering construction (Huainan to Shanghai), this paper put forward a transportation program of 2×multispan circulation cableway with double cable single type. According to the different load quantities, this cableway transportation program divided into independent mode, combined mode and split mode. The testing results show that the cableway transportation program is effective, which can provide reference for related projects.
The self-design and improved pressurized water reactor (PWR) of CPR1000 is used in Yangjiang nuclear power plant (NPP) with two-reactor layout design. The modular method is applied in the construction of containment’s steel lining in No.3 unit, in order to shorten the construction period of cylindrical containment covered with steel lining. This paper introduced the design and construction scheme of modular construction for the steel lining, and put forward suggestions for the modular design and construction, which could provide references for the related projects.
Sanmen AP1000 NPP is different from the general nuclear power units in design, supply and installation due to the application of condenser modular installation. According to the difficulty of modular installation, this paper introduced the installation process, such as supply, hoisting, emplacement and so on, which could provide references for other condenser installation projects in NPP.
