Wind loads are considered to be one of the main harmful factors to threats the structural safety of wind turbine systems. Based on the typical pitch regulated 125 MW steel wind turbine system, an integrated finite element model consisting of the rotor, the nacelle, the tower and the foundation is established using the commercial software ANSYS. Then, on the basis of the random function description of stochastic processes, a physical model of the rotational Fourier spectrum is proposed according to the physical mechanism of wind speeds loading on rotating blades. Furthermore, the wind field of the target site is generated based on the random function method, and the wind-excited dynamic response analysis is thereafter done. In order to evaluate the dynamic amplification effect, the dynamic response results are compared with the static ones. The results show that the wind-induced dynamic amplification effect is remarkable, and this effect should be taken into consideration in the structural design phase. Moreover, obvious beat vibrations exist in the dynamic response analysis of steel wind turbine system, while similar phenomenon does not exist for the reinforced concrete wind turbine system.
Many substation equipments were damaged during Wenchuan earthquake. The seismic behavior of circuit breaker, main component of substation, should be studied. In this paper, shake table tests on a real full size circuit breaker are carried out to study the seismic behavior of the equipment. Seismic responses of accelerations, displacements and the strains of the key parts of the equipment are measured under different ground motions with different levels of peak ground accelerations. These parameters are used to analyze the dynamic characteristics, seismic performance of the equipment as well as the load-carrying capacity of the equipment bracket. The test results show that the bottom of the post insulator is seismic vulnerable part of the equipment due to its complex stress state. Dynamic amplification effects of the equipment bracket should be considered in seismic design of the equipment.
According to the present status of power quality analysis, a novel time-frequency analysis method with high resolution, called time-frequency-adaptive optimal-kernel, is proposed in this paper for investigating the detection of harmonics. This method obtains time-frequency optimal-kernel function by computing ambiguity function of each point in time-frequency plane to suppress cross-term interference caused by multi-component signal under same time, so that high time-frequency resolution is obtained. The method is applied to the analysis of harmonics, and the harmonics amplitude is detected by combining with fast Fourier transform. The test results show that the method describes the frequency and amplitude characteristics of the harmonic components accurately, and harmonics are detected and identified accurately.
With the increment of circuit number in the transmission lines with four-circuit on a tower, the height and width of tower would increase obviously, which could largely influence the lightning withstand performance of the line. In order to accurately assess the lightning withstand performance of both horizontal and vertical tower, the improved electric geometry method(EGM)model and elector-magnetic transient program (EMTP)are applied to calculate the lightning withstand performance of the two tower type under different ground dip angel and grounding resistance. The results show that the lightning performance of horizontal tower is much better than the vertical one. Therefore, it is highly recommended that horizontal tower be applied in mountain area or serious lightning area, while the vertical tower be applied in the area where the line corridor is scarce.
In this paper, the electromagnetic environment for the surrounding of the double-circuit line of a 750 kV substation is studied. Based on the double-circuit overhead transmission line model, the influences of the distance of phase conductors, numbers and spacing of the split conductors, the diameter of the sub-conductor, and the conductor to ground height, on the electric intensity of conductor surface, the radio interference(RI), and the audible noise(AN)are analyzed. Measures to improve the electromagnetic environment are proposed as well.
Corona loss is the important factor in the conductor selection criteria for 1 000 kV UHVAC transmission line. In this paper, the popular corona loss estimation theory is discussed. Based on a practical project, the corona loss is calculated using Bonnevile Power Administration (BPA)model, in which the weather condition is considered. The relationship between corona loss and resistance loss is compared thereafter. The research results could be referenced for future designation on the type of UHVAC transmission line.
In this paper, a mathematical model of instantan eous positive sequence network is built through the instantaneous symmetrical component method. The model built for the 10 kV medium-voltage resonance grounding system, includes the variation of power source, petersen coil, ground capacitance and ground point. Based on this model, the mathematical expression of instantaneous positive sequence current real part and imaginary part in fault branch and unfault branch is derived. The character of the instantaneous positive sequence network is given as follows： in the steady-state after fault, the phase of instantaneous positive sequence current real part in fault branch lags behind unfault branch with a certain angle, while all unfault branches phase is almost equal; the amplitude of instantaneous positive sequence current real part in fault branch is bigger than the one before fault. The simulation finally validates the theoretical analysis.
In this paper, for solving the adaptability and rock creep of foundation using in strongly weathered areas, the belled rock-anchor pile foundation is proposed and applied on the basis of the mechanical characteristics and loading test. The enlarged pile bottom and upper winding anchor technology are used for expanding the scope of application. In addition, the foundation can improve the bearing capacity, effectively slow the development of rock fractures and reduce the displacement of the rock anchor pile, providing references for similar projects.
There are many factors impacting the unbalanced tensile force of the transmission line. To the micro-terrain, the factors including long-span, big altitude difference and large distance difference. Generally speaking, single factor from micro-terrain will not have destructive impact on the transmission line, while the combination of various factors does. In this paper, all possible factors of micro-terrain are assembled, the computation software for unbalanced tensile force is applied and the computation results are achieved for all possible cases. The impact pattern are summarized which can be referenced for future transmission line design and transforming.
In this paper, the intelligent monitoring and auxiliary control system is designed to overcome the shortcomings of current auxiliary production systems for substations. The new system also meets the requirement of smart substation, and provides full monitoring of the substation. The system is combined with video surveillance, security guard, fire alarming, main transformer fire control, heating and ventilation subsystems, which realize the intelligent operation and management of substations.
Field prototype tests are carried out for the newly steel pile foundation during the transformation of country network. The horizontal bearing capacity, the uplift capacity and compressive capacity are obtained. The peculiarities and application modes of the newly steel pile foundation are recommended in emphasis to be referred for similar engineering hereafter.
The method for deciding the angle towers wind load of the conductor and earth wire is discussed, the suggestion is given as well. The formulas of the computation of wind loads are derived. The formulas is a function at the variation of wind loads yield from the wind vertical to conductor and earth wire， the line angle and the wind direction angle. Finally the wind loads are calculated under the combination of both different wind direction angles and line angles.
In this paper, a 3D space analyzing model is built for the structure of 220 kV 2E2-SZ2 transmission tower. The wind speed time-histories relativity between the nodes of the structure is considered, the autoregressive (AR)model is adopted. Under the application of Matlab and Visual C++ mix-programming technique, a 3D wind speed time-histories simulation program of high-voltage transmission tower is developed. The calculation sample shows that the model is accuracy and effective. The model can be referenced in the future analysis of wind-vibration response for the transmission lines.
This paper introduces national provincial wind power development status, the basic condition of Jiuquan wind power base are presented as well. The current status and the operation characteristics is elaborated including the wind resource condition and wind power development and integration. Finally the future problems for the development of wind power is discussed, some suggestions is also proposed.
Under the rules of “East China Regional Power Grid Operation Management Details” and “East China Regional Power Plant Auxiliary Service Management Implementation Details” carried out by East China Power Grid, the existing problems of AGC system are introduced for two sets of 600 MW ultra supercritical units in Tianji power plant. Based on the problems, the methods are presented for improving the economic benefits greatly.
The improving performance of ultra super-critical units is an important research topic at present. In this article, the combustion control and optimization of 2 ultra super-critical boilers are introduced in Huadian Zouxian Power Generation Company. Through the analysis of the combustion control in distributed control system, the logical scheme is modified, and the control parameters optimized, as a result that the combustion and the performance are greatly improved.
In recent years, some new type steam seal have been used in retrofitting of flow passage of stream turbine. It is worthy of studying the heat economy of various steam seal and operation status of retrofitted units. According to steam seal retrofitting results of ten units in Hunan province in 2010, the safety of different steam seal during start up, heat economy before and after transformation and timeliness are analyzed and summarized. The recommendations are valuable to similar transformation of the power plants.
The typical 1 000 MW power unit coordinate system has several widely-known practical problems, such as large fluctuations of key parameters, significant energy consumption under load variation, poor adaptation of coal species, and so on. However, the Infit system, which combine the predictive control technology, the neural network learning technology and the self-adaptive control technique, was used in Huaneng Haimen Power plant. Therefore, the optimal control system, includingthe optimized parameter such as the main stream pressure, mid-point temperature, are achieved. In this paper, key parameters are compared, the research results can be referenced for the operation of similar 1 000 MW power units.
The valve cooling system of convertor station is the important support for the safe and reliable operation of converter valve. The Suidong converter station alarming accident is caused by the high temperature of the water from the valve cooling system, which originates from the instantaneous voltage lostof the cooling system. In this paper, the accident is analyzed and the solution is also given. The operation results show that the solution is feasible and effective.
In the ±500 kV Baoji-Deyang HVDC project, Pole I and Pole II will put into operation in different stages. During the commissioning test of Pole II, the safe and stabe operation of Pole I is guaranteed by the isolation between two pole. In this paper, the interaction between two pole is analyzed in detail, factors are given and summarized. The isolation measures on both software and hardware are proposed, which can be further referenced by similar subsequent projects.
Some uncertain factors of the power grid, such as construction conditions, surrounding environment,etc., are not considered in traditional network planning methods, so that it is difficult to achieve the expected results. A new urban distribution network planning method is proposed, where the boundary elements including load development and power grid construction conditions are considered in determining the locations, capacities and service area of the substations. Then according to the locations and the capacities of substations, the 20/10 kV lines, the medium voltage distribution transformer capacities, the numbers of switching units and the reactive power compensation capacities are estimated. Finally, the assessment, validation and correction of the planed program are implemented. The application results show that the approach is consistent with engineering practice, which has a certain practicality.
Information resources sharing and exchange, integration and standardization of power grid planning, design and construction can enhance its globality, accuracy and adaptability. In the paper, the status of power grid planning data management and the problems existing are introduced. Based on analyzing the characteristics of basic data, the improvement measures of data management, and the suggestions of constructing integrative power grid planning platform are put forward.
Massive foundation is designed to have the ability to prevent settlement. In this paper, a new method is found through the analysis of the current problems in massive foundation. In this new method, the points pit and form erecting of the massive foundation are done through the well locating of the auxiliary piles. We find a new method for the examination of the displacement and torsion of masssive foundation through scientific analysis, in which the computation of two projects can be done through a single examination test.
In this paper, we discuss the construction technologies of rock-socketed bored piles (RCP)through silty clay layer without protection in part by steel protective pipe, which is considered as the most important and difficult part of the whole was demonstrated according to RCP construction practice in the Luotou watercourse sea tower construction work (199 m in height and 2 200 mm in diameter of RCP of the foundation)of the Zhoushan lsland-mainland transmission line interconnection project in China. The main technologies including the construction methods for punching technology, building of steel platform, configuration of protective slurry, quality control of RCP punched aperture, punching methods, the clearance of pits, the installation of steel reinforcement cages and underwater concrete pouring are also introduced.
The wires with large cross section and 6 fissions are applied in ±800 kV Yunnan-Guangdong ultra-high voltage DC transmission line project. It is shown that the synchronized exhibition of one-pulling-four combined with one-pulling-two is economic and reasonable. However, each phase must hang two pulleys for exhibiting the wires. Therefore, a new method for double pulley hanging wires is proposed where the six joint board of the wire is used as the pulley hanging point.
