Transient performance of a single-phase self-regulated self-excited induction generator using a three-phase machine

This paper presents the transient behavior of a three-phase star connected self-excited induction generator (SEIG) using three capacitors connected in series and parallel with a single-phase load. The voltage regulation of this generator is very small due to the effect of three capacitors. The dynamic model of the above generator has been developed based on stationary reference frame d–q-axes theory incorporating the effect of cross-saturation. The steady-state model of the scheme has also been developed. The simulated results of both the transient analysis for the different dynamic conditions, such as initiation of self-excitation, load perturbation and short-circuit and the steady-state analysis are compared with the experimental results. Both the simulated and experimental results are in close agreement with each other.     

Improved Steady State and Transient Performance With Optimum Excitation of Single-Phase Self-Excited Induction Generator

This article deals with the performance prediction and analysis of the two winding single-phase self-excited induction generator (single-phase SEIG). A methodology of selection of capacitors for optimum excitation of the single-phase SEIG scheme is explained. Appropriate dynamic model of the system is developed incorporating the cross-saturation effect. This dynamic model is used for simulating realistic transients, such as no-load and on-load excitation, load perturbation, short-circuit condition, and re-excitation. Simulation results are confirmed by experimental investigation, thus providing verification of the derived model. The results are analyzed to obtain useful guidelines toward system improvements under such transients.     

Transient analysis of self-excited induction Generator with electronic load controller (ELC) supplying static and dynamic loads

This paper presents a transient analysis of a self-excited induction generator (SEIG) with electronic load controller (ELC) used in stand-alone micro-hydro power generation employing uncontrolled turbines. In view of the need to feed both dynamic [three-phase induction motor (IM)] and static loads from such systems, the transient behavior due to switching in of such loads is of interest and is carried out here. A composite mathematical model of the total system has been developed by combining the modeling of prime mover, SEIG, ELC, and load. Simulated results are compared with the experimental ones, obtained on a developed prototype of an SEIG-ELC system for the starting of an IM and switching in a resistive load. For the starting of an IM, a star/delta starter is used to avoid inrush current. Harmonic analysis is carried out to find total harmonic distortion of the terminal voltage and current to assess its power quality.     

Operating performance of static series compensated three-phase self-excited induction generator

The performance of three-phase self-excited induction generator (SEIG) is investigated with static synchronous series compensator (SSSC) and static compensator (STATCOM) to feed static and dynamic loads. The employed compensators are three-phase, Insulated Gate Bipolar Transistor (IGBT) based, Pulse Width Modulation (PWM) operated, Current-Control Voltage Source Converter (CC-VSC). The proposed control techniques employ proportional-integral (PI) controller to generate the reference current. With the designed parameters and control, the SSSC is found effective to regulate load voltage during sudden change of the loads. The SSSC also provides stable operation with dynamic induction motor load and mitigates the unstable and oscillating behavior that is resulting during the operation of compensated SEIG with dynamic motor load. The presented results prove that both SEIG–SSSC and SEIG–STATCOM systems provide satisfactory performance.     

三绕组并联式单相感应电动机起动方式研究

为了保证三绕组并联式单相感应电动机的起动性能,研究了该种电机的动态特性和起动方式.基于电磁关系,建立动态数学模型,并进行仿真计算.为了验证该模型的正确性和有效性,将仿真结果与试验结果进行对比.利用该仿真模型详细分析电容对该种电机起动性能的影响,并给出结构简单的单电容起动电路.仿真和实验结果表明,选择合适的起动电容和运行电容,可以使三绕组并联式单相感应电动机具有良好的起动性能和稳态运行性能.在实际应用中,使用双起动电容电路可以保证良好的起动性能,选择单电容起动电路,可以简化电路结构,节约成本.     

Analysis and application of three-phase induction motor voltagecontroller with improved transient performance

An improved transient performance of three-phase inductance machines with controlled thyristor triggering is presented. A recently developed dynamic function for the thyristor triggering angle is utilized. The triggering angle function influences the phase modulation of the machine-supplied voltage such that the normal transient problems are avoided. Simulation of transients, based on the analytical solution of the machine differential equations, for all modes of operation is provided. The simulation model results show that a smooth switching process for an induction machine, running at any speed, for both motor and generator operation, is achievable. The beneficial effect of the suggested function is smoothing the transient flux, currents and torque is illustrated. Application of the function to different switching conditions is performed with actual laboratory tests     

三相异步电动机阻容制动瞬态过程仿真研究

根据三相异步电动机在α-β静止坐标系下的变参数动态数学模型,编写了一个适合于三相异步电动机阻容制动瞬态过程的实用仿真计算程序,通过实例对三相异步电动机阻容制动运行过程进行仿真计算和分析;根据三相异步发电机稳态等效电路,用最优化方法得到了励磁电容临界值,计算结果与实测结果基本吻合.并对仿真结果进行比较分析,得出了一些有用的结论.     

SemihexTM联接的单相自励感应发电机

对Semihex^TM联接的单相自励感应发电机进行探讨，首先利用对称分量法导出了稳态运行时的等效电路和性能计算公式，并讨论了对称运行条件。样机实验与理论分析结果一致。结果表明，Semihex^TM联接的单相自励感应发电机具有较大的电压变化率。     

The analysis of an ungrounded Wye-Delta transformer bank serving aninduction motor and single-phase lighting loads

This paper documents the detailed analysis of the three-phase ungrounded wye-delta transformer bank serving a combination three-phase induction motor and single-phase lighting load. A 3×3 transfer function matrix is developed that makes it possible to determine the load line-to-line voltages with a knowledge of the primary voltages of the transformer bank. Included in the transfer function matrix are the transformer impedances, unsymmetrical secondary impedance matrix, and the impedances of the motor and single-phase lighting load     

Transient Analysis of Self-Excited Induction Generator Supplying Dynamic Load

This paper deals with the transient analysis of the Self-Excited Induction Generator (SEIG) feeding an induction motor (IM) load. Here, transient performance of the SEIG-IM system has been investigated to assess suitability of the SEIG to sudden switchings, such as starting of the IM. To predict the response of the system, quasi-stationary d-q axes model of the polyphase induction machine has been used. Transient response of the system has been presented for different operating conditions, and sample experimental results are given to validate the predicted ones. Useful guidelines for the design and operation of an SEIG-IM system for an isolated application, such as an IM-driven irrigation pump, have been suggested.     

Adjustable AC capacitor for a single-phase induction motor

The most common practice for starting a single-phase induction machine (SPIM) is to install a starting capacitor in series with the auxiliary winding. In some applications, two capacitors are used. One is used during the starting period to help create the starting torque. The other one is used during the running condition to improve efficiency. The possibility of using an electronic switch in parallel with the running capacitor, thereby providing the equivalent of a starting capacitor, is discussed. The capacitor is shorted during each cycle to vary the effective size of the AC capacitor. By using this method, only one capacitor is used for both the starting and running condition, and a starting performance similar to that of the conventional method using two capacitors can be obtained     

Soft-started induction motor modeling and heating issues for different starting profiles using a flux linkage ABC frame of reference

In order to mitigate the adverse effects of starting torque transients and high inrush currents in induction motors, a popular method is to use electronically controlled soft-starting voltages utilizing series-connected silicon-controlled rectifiers (SCRs). Investigation of semioptimum soft-starting voltage profiles was implemented using a flux linkage ABC frame of reference model of a soft-started three-phase induction motor. A state-space model of the soft-starter thyristor switching sequence for the motor and load was developed and implemented in a time-domain simulation to examine winding heating and shaft stress issues for different starting profiles. Simulation results of line starts and soft starts were compared with measured data through which validation of the model was established. In this paper, different induction machine soft-start profiles are shown, and comparisons of starting times, torque profiles, and heating losses are made. Discussion of these results and conclusions as to the near-optimum types of profiles are delineated based on peak torque, starting times, and winding heating criteria.     

并联补偿电容对自励异步发电机运行性能的影响

针对自励异步发电机自身存在的带负载能力差的缺点,采用并联补偿电容的方法来解决这一问题。以独立运行异步发电机等值电路为基础,令电路的回路阻抗为零,采用降阶消元的简化迭代方法分析异步发电机的稳态运行性能,计算结果与实验结果相吻合,说明了分析方法的正确性。通过比较自励异步发电机带电阻性负载和阻抗性负载时投入不同数值的并联补偿电容后的外特性说明了并联补偿电容能够提高异步发电机的带负载能力。计算还表明,投入并联补偿电容的时机不同会影响异步发电机的电压调整率。通过比较投入前后的最大电压调整率得到了电容的最佳投入时机。     

三绕组串联式高效单相感应电动机瞬态性能

三绕组串联式高效单相感应电动机三个定子绕组串联连接,并与两个电容器连接,可以实现在单相电源下接近对称运行.与同容量普通单相感应电动机相比,具有体积小、效率高的特点.本文从对称分量法和该电机的定子绕组电路结构出发,推导了电机对称运行条件,建立了a-b-c坐标系下的瞬态数学模型.利用该仿真模型分析了电机的动态性能,研究了电...     

Induction Generator Applications for Petroleum and Chemical Plants

A 13 900-hp 1200-r/min induction machine has been applied as a motor/generator in a compressor-expander string associated with a fluid catalytic cracking (FCC) process. Power factor correction capacitors are connected at the terminals of the induction machine. The specific principles of application, as they apply to generator applications, of induction machines are reviewed. Mechanical design, overspeed, excitation, electrical and mechanical transients, and machine control are studied in detail.     

Analysis of a synchronous reluctance machine with an auxiliary single-phase winding

A three-phase synchronous reluctance machine having an axially laminated rotor structure and an auxiliary DC-source-fed single-phase control winding has utility as either a high-speed generator or a high-torque low-speed motor. This paper provides an understanding of its operation using electric circuit and electromagnetic field concepts in the process of which some insights are provided into the design of the windings, conditions for torque production and generation of electric power when operating in the motoring or generating modes. Some confirmatory experimental results of analytical developments are provided showing performance characteristics of an experimental machine.     

晶闸管控制的单相–三相变换器

提出一种单相电源供电时适用于异步电机传动的单相–三相变换器。由于仅采用7个晶闸管和1个移相电容,该变换装置具有造价低、结构简单的特点。分析该变换器的工作原理及开关过程,并提出一种基于开环变压变频(variable voltage variable frequency,VVVF)和变压恒频(variable voltage constant frequency,VVCF)控制的单相–三相离散跳频控制策略,用于电机的起动和稳态运行控制,一方面保证了电机在低频阶段足够大的起动力矩,另一方面可使电机稳步起动到额定转速。仿真和实验结果表明了该控制策略的有效性以及系统方案的可行性。     

Fault classification in SEIG system using Hilbert-Huang transform and least square support vector machine

This paper presents the transient performance analysis of self excited induction generator (SEIG) during both balanced and unbalanced faults using stationary frame d–q axis. Significance of fault detection and fault classification is also investigated in this study. Current signal of SEIG is extracted. Non stationary distorted current waveforms of SEIG during fault condition are considered as superimposition of various oscillating modes. To separate out these oscillating components known as intrinsic mode functions (IMFs), empirical-mode decomposition (EMD) is used. Hilbert transform (HT) is applied on the first four IMFs to extract instantaneous amplitude and frequency. Combination of EMD and HT is known as Hilbert-Huang transform. To classify different faults of SEIG system, least square support vector machine (LSSVM) is used. Finally the superiority of the proposed SVM is established through comparison with support vector machine and probabilistic neural network.     

新型三绕组并联式高效单相感应电动机稳态性能

提出一种新型的三绕组高效单相感应电动机,其定子上有3个绕组,与2个外接电容连接,采用单相交流电源供电,3个绕组所在的支路之间为并联关系。通过电容的适当选择,可使该电机在额定运行时3个绕组的电流接近对称。基于合成电流法,对该接法电机的对称运行条件进行分析,得出了电容的确定方法;提出了该电机稳态性能计算的具体方法;设计了一台样机,并进行了试验研究。结果表明,该新型电动机在额定负载下运行时,具有与同容量三相感应电动机相近的效率和更高的功率因数。     

HIGH-EFFICIENCY SINGLE-PHASE SEMIHEX™ MOTORS

ABSTRACT

These single-phase motors can now have the high efficiency of 3-phase motors. They are a three-phase construction with a SEMIHEX? connection of the windings to two run capacitors. Nearly all single-phase products, and particularly air conditioners, can use these high-efficiency motors. These can save billions of dollars for the consumers. The single-phase winding currents at full load are the same as if the motors were connected to a 3-phase source. The single-phase full-load efficiencies are the same high efficiencies as the 3-phase motor on a three-phase supply. The power line sees a leading power factor of approximately 87%. The single-phase line current is approximately 1.7 times what the three-phase line current would be. The line starting current is unity power factor and is less than three times the full-load current for motors between 10-HP and 100-HP. Single-phase motors as large as 100 horsepower are readily built at low cost.