晶闸管中频电源在电磁铸造领域的应用

本文介绍了晶闸管中频电源装置在电磁铸造工艺上的应用情况，以及感应线圈电流、频率、电压和功率等电参数的选择方法。     

圆管感应加热工件内电参数的计算

把圆管感应加热时的电磁场看成是一维轴对称场,解得各场量,应用坡印亭向量从理论上导出了圆管感应加热时各电参数的理论计算公式,并借助于计算机获取了精确的计算系数值,为圆管感应加热的设计计算提供了准确、实用的方法。     

LF／VD—100t钢包精炼炉的设计

介绍了上钢三厂ＬＦ／ＶＤ－１００ｔ钢包精炼炉的总体布置、电参数确定，以及铜钢复合导电横臂、水冷炉盖的设计。     

LF／VD－100t钢包精炼炉的设计

介绍了上钢三厂ＬＦ／ＶＤ－１００ｔ钢包精炼炉的总体布置、电参数确定，以及铜钢复合导电横臂、水冷炉盖的设计。     

MI-AlxGa 1-xAs/GaAs太阳电池中界面势的构成及其界面复合分析

在MIp-AlxGa1-xAs结构的I层表面上，引入固定负电荷，并用减反射膜覆盖。将p-Al1-xGaxAs层中的空穴感应至界面，可建立界面电子感应势垒，并将其构成MIp-AlxGa1-xAs/p-n-n^ -GaAs太阳电池。通过求解泊松方程，理论上分析了界面感应势的高度、宽度与p-AlxGa1-xAs层掺杂浓度及减反射膜中固定负电荷面密度的关系，以及该感应势的建立对电池界面复合速度的影响。结果表明，p-AlxGa1-xAs层掺杂浓度的降低以及固定负电荷面密度的增高，都将导致界面感应势的高度与宽度的增加，从而能有效降低电池界面复合速度几个量级，相应地可大大提高电池的开路电压。     

含发电机及多感应电动机工业负荷母线失电残压分析

大型工业企业由于同一母线上电动机数量多,且为关键负荷需要不间断运行,母线失电残压的特性研究可为后续备用电源的平稳投入提供基础。针对含发电机以及多台感应电动机的工业负荷母线的失电残压特性进行了深入研究。首先,以单台电动机为例,提出基于轨迹灵敏度方法分析影响失电残压动态特性的关键参数。针对多台感应电动机的负荷母线,研究了电动机容量、负荷率等参数对失电残压的影响规律。最后,研究了负荷母线自备电源对失电残压的影响规律,指出同步发电机额定容量是影响母线残压的关键因素,强调同步发电机稳态出力与其暂态无功支撑能力的关系。     

无心感应熔炼炉的优化分析与设计—感应器-炉料系统的综合电模型及其应用

本文对无心感应熔炼炉感应器—炉料系统电磁场等效电路模型进行了数学处理,导出了其电效率、功率因数、阻抗与原始参数间的显函关系。为感应炉的分析设计提供了简明实用的数学模型。     

电袋复合除尘器改造方案的技术经济性分析

以某电厂300 MW机组电袋复合除尘器改造为例,通过对改造方案的参数设计、这体投资、运行费用、大修及维护费用的比较,确定了一种较为合适改造方案.同时为同类电袋复合除尘器改造设计提供了有价值的参考.     

感应加热的数值计算

本文用数值方法求解感应加热的技术问题。数值方法具有快速、准确、经济的优点,藉助数字计算机可以完全按照数学模型求解实际问题。感应加热过程中物理变化迅速、物理参数多,且波动比较剧烈,但用数值方法仍然能够比较准确的重现电的和热的过程。 本文对数学模型进行了推导、运算,并编制了INDUCT程序系统。该系统包括多个相互独立的程序,其中针对大尺寸、等截面圆柱形锻造毛坯往复式感应加热的特点编制了INDUCOSI程序。     

连续感应热处理生产线的计算机闭环控制

连续感应热处理过程存在着强电磁场干扰，非线性，强噪声和过程参数多变性，传统的控制方法难以奏效。本文针对抽油杆的连续感应中频热处理过程，介绍了以ＰＣ总线工控计算机为核心的智能控制系统。     

Analysis of the induction machine parameter identification

This paper analyzes the numerical identifiability of the electrical parameters of induction machines. Formulations of the single and double-cage induction machine, with and without core-losses in both models, are developed. The impossibility of identifying all the parameters of these models when only external measurements (voltage, current, speed and torque) are used is shown. One proposed solution is the formulation of machine equations by using the minimum number of parameters (which are identifiable parameters). As an application example, the parameters of a double-cage induction machine are identified using steady-state measurements corresponding to different angular speeds     

Calculation of machine winding electrical parameters at highfrequencies for switching transient studies

This paper describes a multiconductor transmission line approach for calculating the machine winding electrical parameters for switching transient studies. The technique is based upon the solution of the one dimension diffusion equation in the slot of electrical machines. The coil electrical parameters are calculated considering both the magnetic flux in the iron and in the air. Several practical formulations for calculating the winding electrical parameter are proposed which take into account the machine winding design characteristics. The computer models are validated by a comparison of measured and calculated results in two high voltage induction motors     

Estimation of induction motor double-cage model parameters from manufacturer data

This paper presents a numerical method for the estimation of induction motor double-cage model parameters from standard manufacturer data: full load mechanical power (rated power), full load reactive electrical power, breakdown torque, and starting current and torque. A model sensitivity analysis for the various electrical parameters shows that stator resistance is the least significant parameter. The nonlinear equations to be solved for the parameters determination are formulated as a minimization problem with restrictions. The method has been tested with 223 motors from different manufacturers, with an average value of the normalized residual error of 1.39/spl middot/10/sup -2/. The estimated parameters of these motors are graphically represented as a function of the rated power.     

Electromagnetic design and optimization of dual‐stator brushless doubly‐fed wind power generator with cage‐barrier rotor

This paper explores the feasibility of an intuitive solution torque density for the existing brushless doubly‐fed generator by dual‐stator and cage‐barrier rotor structure, so as to better adapt to the offshore wind power generation. The torque density of electrical machine is related to the key design parameters, such as the machine main dimensions, slot‐pole combinations, coupling between stator and rotor, and nonmagnetic ring thickness. According to working principles and design requirements of electrical machine, the dual‐stator brushless doubly‐fed wind power generator (DSBDFWPG) with cage‐barrier rotor is designed, and the key parameters relating to torque density are analyzed and discussed. Meanwhile, the main parameters of electrical machine are optimized by Taguchi method, such as air‐gap length and nonmagnetic ring thickness. On this basis, the performance parameters of DSBDFWPG are analyzed by finite element method, which is verified by experimental tests. Through analysis of the results, not only the design requirements are satisfied by the DSBDFWPG, but also the correctness and rationality of machine design method can also be verified. Finally, the torque density and other aspects of designed DSBDFWPG are compared with dual‐stator brushless doubly‐fed induction generator, doubly‐fed induction generator, asynchronous machine, and brushless doubly‐fed generator; it demonstrates the torque density improvement of the studied machine with its significance and value.     

Two-Step Method for Identification of Nonlinear Model of Induction Machine

A two-step method is applied for parameter identification of a saturated electromechanical model of an induction machine (IM). The k-factor cross saturation technique is used to account for iron saturation. Balanced and unbalanced short-circuits armature current waveforms of this machine are less sensitive to variations in the mechanical parameters. Conversely, any change in these parameters has a strong impact on the start-up test. Accordingly, in the proposed estimation method, the online double-line-to-neutral short-circuit test is performed to estimate the electrical parameters of the machine and the results obtained are then used to compute the mechanical parameters from the starting test. The good agreement of the estimated results with actual data attests to the effectiveness and suitability of the proposed algorithm in computing the electromechanical parameters of these machines.     

Optimization of Three-Phase Induction Motor Design Part I: Formulation of the Optimization Technique

This two-part paper deals with the optimization of the induction motor designs with respect to cost and efficiency. Most studies on the design of an induction motor using optimization techniques are concerned with the minimization of the motor cost and describe the optimization technique that was employed, giving the results of a single (or several) optimal design(s). In the present paper, a more comprehensive study on the optimization of a three-phase induction motor design was performed. This includes the relationship between motor cost, efficiency, and power factor; the effect of the properties of the electrical steel; and other effects as they occur in an optimal design. In addition, the optimization procedure that was used in this paper includes a design program, where some of the secondary parameters (which are called here variable constants), are modified according to the optimal results, in contrast to other studies where these parameters remain constant for the entire optimization. In this part, a new mathematical formulation of the optimization problem of the induction motor is presented.     

大型风电场失速型机组等值建模的研究

对于风电场中失速型机组的多机等值,采用异步发电机的机电暂态模型求解发电机组的等值电气参数,利用基于传递函数概念的参数辨识方法及最小二乘法求解发电机组的动态等值参数。利用系统等值得结果对一实例进行仿真,结果表明了等值方法的有效性和正确性,为今后研究风电场与电网之间的相互影响提供了良好的模型基础。     

Calculation of electromagnetic induction inside a wind turbine tower struck by lightning

An efficient algorithm is described in this paper for calculating the magnetic transient effects in a wind turbine tower struck by lightning. An electrical network model of the tower is established to compute the transient responses on its surface, and the electrical parameters of the network are determined considering the effect of ground. Based on the transient current responses along the tower conductors, the evaluation of magnetic field distribution is presented directly in time domain, and the transient overvoltage induced in a loop is also calculated according to the law of electromagnetic induction. The results are helpful in determining possible hazards and designing lightning protection systems. © 2009 John Wiley & Sons, Ltd.     

Wind turbine productivity considering electrical subassembly reliability

This paper proposes a reliability model for the electrical subassemblies of geared wind turbine systems with induction generators. The model is derived considering the failure of main subassemblies and their parameters are calculated. A productivity comparison is performed between the selected wind turbine systems including reliability issues.Two methods of modification for variable-speed wind turbines with Doubly Fed Induction Generators (DFIG) to improve their availability are finally suggested.     

Reduced models of doubly fed induction generator system for wind turbine simulations

This article compares three reduced models with a detailed model of a doubly fed induction generator system for wind turbine applications. The comparisons are based on simulations only. The main idea is to provide reduced generator models which are appropriate to simulate normal wind turbine operation in aeroelastic wind turbine models, e.g. for control system design or structural design of the wind turbine. The electrical behaviour such as grid influence will therefore not be considered. The work presented in this article shows that with an ideal, undisturbed grid the dynamics of the doubly fed induction generator system is very well represented by the dynamics due to the generator inertia and the generator control system, whereas the electromagnetic characteristics of the generator can be represented by the steady state relations. The parameters for the proposed models are derived from parameters typically available from the generator data sheet and from the controller settings. Thus the models are simple to apply in any case where the generator data sheet is available. Copyright © 2005 John Wiley & Sons, Ltd.