Clustering of voltage control areas in power system using shuffled frog-leaping algorithm

Determination of critical voltage control areas (VCAs) is a very important task in both voltage stability assessment and control. However, it is impossible to detect VCAs in real time during appearance of emergency cases for large-scale power systems. Therefore, it is a reasonable solution to employ an artificial intelligent system (AIS) to detect VCAs and to identify the prone buses for monitoring and control purposes as quickly as possible. The training data must contain the simulation results and the historical data collected from a wide range of various emergency cases. Using this database, a clustering process which provides finite clusters of all possible VCAs and a classification function which affiliates each emergency or stress case to its own cluster of VCAs are the main stages to prepare AIS for automatic VCA identification. In this paper a novel data clustering method based on shuffled frog-leaping algorithm (SFLA) is presented for the first task. The results are finite numbers of clustered groups of VCAs with a representative vector of participation factors (PF) for each group. SFLA combines the benefits of the genetic-based memetic algorithms as well as social behavior-based particle swarm optimization methods. In present study the application of SFLA in data clustering is also compared with the most popular analytic algorithm of clustering, K-means, and also with genetic algorithm-based data clustering to demonstrate the validity of proposed clustering method. Numerical results are also presented for IEEE 14-bus test system and an artificial database. The comparative results show the effectiveness of proposed algorithm.     

New mathematical models of an induction motor using a minimum number of parameters

This paper proposes new mathematical models of an induction motor that generates torque precisely under vector control. The proposed models for the controlled motor have desirable features in respect to preciseness and compactness. They guarantee the same relation between the stator voltage and current signals as does the conventional T‐type model consisting of five parameters. The number of parameters forming the new models is reduced to four, such as stator resistance, inverse of rotor time constant, stator inductance, and stator total leakage inductance, or another set of four related uniquely to them. The parameters are uniquely determined by the stator signals, in terms of which all controller parameters of the vector control system can be designed. ©1998 Scripta Technica, Electr Eng Jpn, 126(2): 48–55, 1999     

一种十五相感应电机的矢量控制算法

在已有多相电机系统研究的基础上,研究了一种新型的十五相感应电机矢量控制算法.详细推导了该种十五相感应电机的数学模型,并在此基础上推导了十五相感应电机的矢量控制算法,给出了系统的控制框图.系统试验结果表明了该矢量控制算法的正确性和可行性,将该算法应用于实际的十五相感应电机矢量控制系统中,可以取得对电机良好的控制效果,该十五相感应电机矢量控制算法可直接应用于兆瓦级大功率十五相感应电机系统中.     

应用遗传算法辨识天窗驱动电机关键设计参数

针对汽车天窗驱动电机额定指标确定困难的问题,利用样机实测的结构参数并结合电机磁路计算中的主要系数,建立汽车天窗驱动电机电磁计算模型,并得到初始设计方案.在此基础上,应用遗传算法,以系统输出转速和实测转速偏差最小为目标,对天窗驱动电机关键参数进行辨识.通过辨识参数所确定的天窗驱动电机设计方案与样机实测数据和初始设计方案的...     

Estimation of the parameters of metal oxide gapless surge arrester equivalent circuit models using genetic algorithm

In the present work a genetic algorithm is developed, for the evaluation of the parameters of metal oxide gapless surge arrester circuit models, in order to minimize the error between the computed and the measured (by the manufacturer) peak value of the residual voltage for each given current waveform and level separately. Furthermore, the algorithm is modified in order to minimize the error simultaneously for all the given injected impulse (lightning and switching) current curves.     

用神经网络实现对感应电机转速估计

根据数学模型．提出了一种利用神经网络进行感应电机转速估计的新方法。方法是采用一个3层神经网络作为速度估计器来估计转速。仿真结果表明，这种基于人工神经网络的转速估计模型可以准确地跟踪感应电机转速的变化，具有良好的动态跟随性能。     

On-line determination of nonlinear parameters of induction motor with squirrel-cage rotor

New mathematical relationships for the contactless determination of the active resistance of the rotor winding, excitation circuit inductance, and the electromagnetic time constant of the rotor are presented for an operating motor. The relations include parameters that are available for direct measurement in the control system or known from the design documentation and needed for calculations. We have revealed new interdependences between the basic parameters of operating frequency-controlled induction motors for any mode at different saturations of the magnetic circuit and any temperature of stator and rotor windings.     

一种自适应补偿死区的异步电机参数测量方法

针对异步电机参数静止测量精度受变频器控制中死区影响较大的问题,提出了一种死区自适应补偿的电机参数静止测量新方法。采用比例谐振(PR)控制器自适应补偿变频器电流的死区效应,采用PR锁相环和死区影响特征减轻交流电压波形因死区补偿产生的畸变,采用死区估算结果减少直流电压受死区非线性影响。变频器控制测量异步电机参数实验结果表明新方法得到的交流电流和电压THD分别小于传统方法 8.92%和7.65%,消除畸变的交流电压幅值和相角得到有效补偿、且幅值波动变小,直流量电压受死区非线性影响减少。提出的测量方法相对于传统方法可提高参数测量精度大于6.4%。     

Direct-drive induction motors: using an induction motor as an alternative to a motor with reducer

This article presents the performance and size comparisons of direct-drive induction motors with gearbox-driven systems. Three different low-speed applications with output speeds to the driven equipment ranging from 300-600 r/min is reviewed. In addition, permanent-magnet (PM) motor advantages and disadvantages are also discussed.     

Estimation of multilayer soil parameters using genetic algorithms

A methodology has been proposed according to which, after carrying out a set of soil's resistivity measurements, one can compute the parameters of the multilayer earth structure using a genetic algorithm (GA). The results provided by the GA constitute the indispensable data that can be used in circuital or field simulations of grounding systems. The methodology, developed on the base of the PC Opera software package, allows to proceed toward a very efficient simulation of the grounding system and an accurate calculation of potential on the ground's surface.     

Position control of the induction motor using a passivity-basedcontroller

Most position tracking applications employ either DC or permanent-magnet motors. In this paper, an induction motor drive for position control applications is proposed. Such a drive adopts a passivity-based controller which mainly differs from the others because its formulation emphasizes system energy properties and behavior. The controller has simple equations and good robustness without using complex flux observers and the exact knowledge of the motor parameters, as well. The proposed drive has been practically implemented, achieving satisfactory results     

Field-oriented control of an induction motor with robust on-linetuning of its parameters

This paper proposes new torque control of an induction motor, which is robust against primary resistance and adaptable to leakage inductance, magnetizing inductance, and secondary time constant. The control is based on flux feedback with a flux simulator. Since the simulator is based on a rotor current model, it is independent of the primary resistance, but uses the magnetizing inductance and secondary time constant values to estimate the flux. Parameter mismatch in the simulator detrimentally affects flux and torque responses. In order to compensate for degradation of the responses, an identifier for the magnetizing inductance and the secondary time constant is introduced. The identifier is insensitive to the primary resistance because it is based on instantaneous reactive power of the motor. Also, a leakage inductance identifier is introduced to achieve perfect compensation, which is robust against other parameters owing to instantaneous harmonic reactive power. To verify feasibility of the proposed technique, digital simulations and experimental tests have been conducted. The results have proven excellent characteristics of the drive system, which confirms validity of the scheme     

一种感应电机预测控制的电流静差消除方法

感应电机电流预测控制可以有效避免由电流环中各个滞后环节所导致的控制性能恶化,提高电流控制的动态性能。但由于测量误差以及参数变化等原因,预测控制器所使用的感应电机模型参数与实际电机参数很有可能存在偏差,进而引起电流静差,导致系统效率降低,无法输出额定转矩及无法工作在转矩控制模式等问题。在感应电机模型基础上,定量分析了预测控制模型参数误差对电流控制稳定性的影响,并推导出电流指令与实际反馈电流的静差与模型参数误差两者之间的定量关系,进而提出一种电流静差消除方法。这种方法通过d、q轴反馈电流对预测控制模型参数进行校正,来消除控制器电机模型参数误差所引起的静差。最后通过实验验证了此种方法的可靠性和有效性。     

Experimental determination of parameters for an induction motor with a short-circuited rotor

Problems of experimental determination of parameters of induction motors with a short-circuited rotor in different operating regimes are considered. The equations of a generalized electrical machine are reduced to a form that allows identification of four independent parameters—the constant time of the rotor, stator inductance, stator active resistance, and generalized dissipation. It is shown that measuring the rotation frequency, voltages, currents, and electromagnetic torque allow estimation of the values of these parameters, but not five parameters of the standard phase-substitution circuit of the induction motor. Examples of experimental determination of parameters and parameters’ dependence on the operation regime of a traction motor are given.     

Speed sensorless vector control of induction motor using extendedKalman filter

A vector control of an induction motor by an estimated speed using an extended Kalman filter is proposed. With this method, the states are composed of stator current and rotor flux. The rotor speed is regarded as a parameter, and the composite states consist of the original states and the rotor speed. The extended Kalman filter is employed to identify the speed of an induction motor and rotor flux based on the measured quantities such as stator currents and DC link voltage. The estimated speed is used for vector control and overall speed control. Since the current control is performed at a synchronous rotating reference frame, the estimated speed information is also used for the reference frame transformation of the current controller. Computer simulations and experiments of the speed control have been carried out to test the usefulness of the speed estimation algorithm. The experimental results show that the performance of the speed estimation is very good     

Two-dimensional analysis of linear induction motor using Fourier's series method

Contents A single sided linear induction motor with finite length of the primary is considered. Calculations of magnetic flux density, secondary current, forces and power losses in two layers of a secondary are based on Fourier's series method. Variation of magnetic flux density across an air-gap and finite values of permeability and conductivity of the secondary back iron were taken into account in the computational model. Calculations were compared with test results.

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Zweidimensionale Analyse des linearen Induktionsmotors nach der Methode harmonischer Fourierreihen

Übersicht Es wird ein einseitiger linearer Induktionsmotor bei Berücksichtigung endlicher Strombelaglänge betrachtet. magnetische Induktion, Strom-, Kraft-und Verlustdichte in zwei Schichten des Sekundärteiles wurden auf Grund der Methode harmonischer Fourierreihen berechnet. Im rechnerischen Modell wurde die Änderung der magnetischen Induktion im Spalt und der endliche Wert der magnetischen Induktion im Spalt und der endliche Wert der magnetischen Permeabilität sowie der Leitfähigkeit von Eisen im Sekundärteil berücksichtigt. Die Berechnungen wurden mit Ergebnissen experimenteller Untersuchungen verglichen.

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List of symbols and abbreviations a primary width - B magnetic flux density - b slot opening - c secondary width - d conducting plate thickness - E electric field intensity - F force - f force density - H magnetic field intensity - J current density - J ^s primary linear current density - J ^r secondary linear current density - K _t finite primary width correction factor - K _b Carter's coefficient - k, u, i harmonic and wave number - L primary length - q number of slots per pole per phase - s slip - v secondary speed relative to primary - v _ijk speed of the kui field harmonic - w _s number of wires per slot - P _e secondary power losses - p _e secondary power loss density - modified air-gap length - _a actual air-gap length - permeability - modified air-gap length - permeability - modified secondary conductivity - _a actual secondary conductivity - [ _s –L] distance between adjacent primaries - _t tooth pitch - _z pole pitch - Q - Q* conjugate value ofQ     

Parameter identification of deep-bar induction motors using genetic algorithm

In recent years, the use of three-phase deep-bar induction motors in power systems has increased. Proper modeling and precise parameter identification of the model are essential for motors’ operating analysis. In this paper, among the proposed models of deep-bar induction motors, a model based on two-axis theory is discussed and developed to improve precision. A real coded genetic algorithm estimates the parameters of the model. The accuracy and validity of the model and its identified parameters are verified with the help of a 5.5 kW, 380 V, 50 Hz, 1,450 rpm deep-bar induction motor.     

Nonlinear adaptive state-feedback speed control of a voltage-fed induction motor with varying parameters

An adaptive nonlinear-state-feedback speed control scheme of a voltage-fed induction motor has been developed in which the control of torque and flux is decoupled. The inputs to the control algorithm are the reference speed, the reference flux, the measured stator currents, the measured rotor speed, the estimated rotor flux, and estimates of the rotor resistance, stator resistance, and load torque, which may vary during operation. The controller outputs are the reference stator voltages in rotor-flux rotating reference frame. An accurate knowledge of the rotor flux and machine parameters is the key factor in obtaining a high-performance and high-efficiency induction-motor drive. The rotor flux is estimated using the induction-motor rotor-circuit model. Although the estimated rotor flux is insensitive to the stator-resistance variation, it does depend on the rotor resistance. A stable model reference adaptive system (MRAS) rotor-resistance estimator insensitive to stator-resistance variation has been designed. Stable stator-resistance and load-torque MRAS estimators have also been developed. These estimators have been developed to constitute a multi-input-multi-output (MIMO) decoupled-cascade structure control system. This simplifies the design problem of the estimators for a stable operation from a MIMO design problem to a single-input-single-output (SISO) design problem. The continuous adaptive update of the machine parameters and load torque ensures accurate flux estimation and high-performance operation. Simulation and experimental results are presented to verify the stability of the induction-motor drive in various operating modes.