Wound Rotor Research Articles

A Comparative Study on Conventional and Superconducting Electrical Machines

This paper investigates the potential benefits of utilizing superconducting materials in machines. The project focuses on replacing the conventional copper windings with superconducting materials in a machine. The machine is modelled and simulated using ANSYS software, both with conventional copper windings and with superconducting windings. A 3.7kw and 11kw 3 phase Induction machines are simulated with YBCO material applied to stator and rotor windings. The results show that the use of superconducting materials in the machine windings can significantly reduce energy losses and improve machine efficiency by 1 to 10%. Overall, the study suggests that superconducting machines offer a promising avenue for improving energy efficiency and reducing operating costs.

МОДЕЛИРОВАНИЕ АСИНХРОННОГО ЭЛЕКТРОПРИВОДА ДЛЯ ИССЛЕДОВАНИЯ ПРОЦЕССА ПУСКА

A model of an asynchronous motor is proposed, which makes it possible to investigate the process of motor acceleration, taking into account changes in the resistance of the rotor circuit, consumed current and voltage in the power supply network. A method for calculating the parameters of the equivalent circuit of an asynchronous motor according to passport data is proposed, the calculation takes into account changes in the resistance of the rotor circuit during start-up. The electric motor model is based on a static mechanical characteristic with a linear dependence of the rotor resistance on slip. The model is designed to study the electromechanical parameters of the electric drive during the start-up process, taking into account the parameters of the power supply circuit. The analysis of existing functions for modeling the mechanical characteristics of an induction motor was carried out and a formula was chosen for determining the electromagnetic torque from the parameters of a simplified L-shaped equivalent circuit without taking into account electromagnetic transients. Therefore, the proposed model based on the static mechanical characteristic is applicable for mechanisms with a long start. The parameters of the equivalent circuit of an asynchronous motor are determined according to the passport data. The dependence of the rotor circuit resistance on slip is described by a linear function of the first order. The results of calculating the mechanical characteristic according to the compiled model do not differ from the parameters at four known characteristic points corresponding to the passport data of the induction motor. Because when calculating the no-load current and the active resistances of the stator and rotor windings, some assumptions were made, it should be noted that the proposed method is preferable for calculating high-power motors.

Secures and maintains non-linear control of DFIG-wind turbine by implementing the appropriate protection configuration against overcurrent in the rotor circuit under grid fault

One significant disadvantage of the doubly fed induction generator (DFIG) is its high vulnerability to grid faults, which can be attributed to the direct linkage of its stator windings to the electrical network. The electromagnetic pairing of the stator and rotor in the DFIG implies that a voltage dip causing excessive stator current results in high currents in the sensitive back-to-back inverters and an overcharge in the DC-link capacitor. A comparative study of two protection configurations with a sliding mode non-linear control (SMC) for the rotor transient current for the better operation of the DFIG under network faults is presented in this document. One conventional configuration consists of a crowbar with DC-chopper and another is changed by adding to the crowbar an RL series device known as an appropriate protection configuration (APC). Both are placed within the rotor windings and ride-side converter (RSC) to achieve secures and maintains SMC of DFIG. The comparison of the results reached with the MATLAB/ SIMULINK application is evidenced by the success of these two configuration reduce the high rotor current and DC-link voltage. Additionally, the conventional configuration, in conjunction with the APC, diminishes the current RSC to levels below 0.2kA and exactly 2.25kA, while also being capable of absorbing up to 2.52kA and 1.3kA in the event of a grid fault. So the main difference is that with the APC, the decoupling of the RSC to the rotor in the presence of a fault can be averted, thereby assuring the control of all stator power via the RSC converte.

New Actuator Disk Model for the Analysis of Wind Turbines Wake Interaction with the Ground

Wake models based on Actuator Disk theory are usually applied to optimize the wind farm layouts and improve their overall efficiency and expected AEP. Despite the effectiveness of the existing models, most Actuator Disk approaches are based on the flow axisymmetric assumption, without considering the ground effect on the wake behavior. However, it has been shown that the mast’s height, or distance from the wind turbine to the ground, has an influence on the wake expansion on both hub’s side and at downstream of the wind turbine. Therefore, in this study, a hybrid CFD-BEM-Actuator Disk approach is developed to address the lack of the existing models. In the proposed model, the 3D wind rotor is modeled by a set of blade elements. Then, the local lift and drag forces acting on each blade element are calculated using BEM theory and incorporated into the momentum equation. This BEM-AD model is implemented in a User Defined Function (UDF) that is loaded into the CFD software. Thereby, ground effects are considered to be a wall boundary and defining a wind boundary layer profile at the inlet boundary, which describes the Atmospheric Boundary Layer (ABL). For the validation of this new Actuator Disk model, an enhanced experimental study is conducted at the Dynfluid Laboratory wind tunnel (ENSAM School Paris Tech). The Particle Image Velocimetry (PIV) measurements are used for the experimental wake explorations applied to a miniature two-bladed wind turbine. The wake developments are analyzed at two different hub heights ratio, h/D = 0.7 and 1.0 (where h is the hub height, and D is the wind rotor diameter). The analysis of the outcomes showed that the numerical simulations are in good correlation with the experimental measurements of the ENSAM wind tunnel. The numerical results show that for h/D=0.7, the upper half of the rotor operates within the boundary layer whereas the lower tip vortices are mainly developed in the horizontal direction with lower intensity compared to the upper tip vortices. This effect was not observed for the case h/D=1.0 where the rotor operates outside of the boundary layer; however, the wake centerline is upward deflected at about 0.3D. The main conclusion is that a distance above 7D must be observed between wind turbines to optimize the wind farm performance and over 1D hub height be required to limit the influence of the ground boundary layer effect.

A novel adaptive variable speed control strategy for wound rotor induction motors

A novel adaptive variable speed control strategy for wound rotor induction motors

Performance Comparison of Large-Scale Design-Optimized Non-Overlap and Overlap Winding Wound Rotor Synchronous Generators

The use of non-overlap windings rather than overlap windings is a topic for debate. Non-overlap windings are generally cheaper and easier to manufacture but result in a high amount of magnetomotive force sub- and higher-order harmonics. A strategy to reduce these harmonics has been previously published and this study aims to provide a performance comparison of a large-scale wound rotor synchronous generator with a modified non-overlap winding and a classical overlap winding. Hence, design optimisations of a 16/18 and 16/72 pole/slot grid-connected 3 MW wound rotor synchronous generator for medium-speed wind generation are conducted. The optimisations are performed using the modified method of feasible direction gradient-based optimisation because of its simplicity and fast results. Optimal solutions for the 16/18 and 16/72 3 MW models are obtained and the performance of the solutions compared. The results show that the 3 MW 16/18 model performs favourably against the 3 MW 16/72 model, especially regarding the lower active mass.

Brushless Wound Rotor Vernier Motor Using Single-Phase Additional Winding on Stator for Variable Speed Applications

Brushless Wound Rotor Vernier Motor Using Single-Phase Additional Winding on Stator for Variable Speed Applications

Performance Analysis of Brushless Wound Rotor Vernier Machine by Utilizing Third Harmonic Field Excitation

Performance Analysis of Brushless Wound Rotor Vernier Machine by Utilizing Third Harmonic Field Excitation

A novel adaptive variable speed control strategy for wound rotor induction motors

A new approach is proposed for the design of an adaptive variable speed controller for an induction motor. This design approach is based on a new model for induction motors in the (α/β) reference frame. The model state variables are constant in steady state and therefore enable the application of adaptive backstepping control design techniques to find controller equations and adaptation laws that ensure that the rotor speed and flux track their reference values despite significant changes in machine resistances and inductances due to temperature and magnetic saturation. The proposed controller is tested in simulation. Results show robust steady state and transient performances.

Comparative Study of Induction and Wound Rotor Synchronous Motors for the Traction Drive of a Mining Dump Truck Operating in Wide Constant Power Speed Range

Comparative Study of Induction and Wound Rotor Synchronous Motors for the Traction Drive of a Mining Dump Truck Operating in Wide Constant Power Speed Range

Static modes of electromagnetic working shaft (EMWSh)

In this paper, the issues of ensuring the statically stable operation of a two-motor electric drive are considered, EMWSh, has been developed. A distinctive feature of EMWSh is the connection of the rotor windings of two or more motors to the power windings of an induction rheostat (IR), some issues of the practical application of EMWSh systems in multi-motor electric drives for movement mechanisms of cranes and long conveyor lines.

High Reliable Lead Wire System of the Rotor Winding in Pumped Storage Power Stations

High Reliable Lead Wire System of the Rotor Winding in Pumped Storage Power Stations

Static modes of an electromagnetic working shaft (EMWSh) and an electro-electromagnetic working shaft (EEMWSh) with the inclusion of a capacitor in the rotor circuit of the motors

In this paper, the issues of ensuring the statically stable operation of a two-motor electric drive are considered, a fundamentally new system of coordinated rotation of asynchronous motors based on an electromagnetic working shaft (EMWSh) has been developed. A distinctive feature of EMWSh is the connection of the rotor windings of two or more motors to the power windings of an induction rheostat (IR) and capacitors. The issues of practical application of EMWSh and electroelectromagnetic working shaft EEMWSh with the inclusion of a capacitor in the rotor circuit of motor systems in multi-motor electric drives of crane movement mechanisms and long conveyor lines are studied.

Weak Fault Detection of Rotor Winding Inter-Turn Short Circuit in Excitation System Based on Residual Interval Observer

Weak Fault Detection of Rotor Winding Inter-Turn Short Circuit in Excitation System Based on Residual Interval Observer

ДИНАМИЧЕСКАЯ ИДЕНТИФИКАЦИЯ ПАРАМЕТРОВ СХЕМЫ ЗАМЕЩЕНИЯ АСИНХРОННОГО ДВИГАТЕЛЯ НА ОСНОВЕ БАЛАНСА МГНОВЕННОЙ ПОЛНОЙ МОЩНОСТИ В УСТАНОВИВШЕМСЯ РЕЖИМЕ

The relevance Automated electric drive (AED) is one of the most important and most common control objects in automatic process control systems (ACS). The control of the output coordinate in the AED, for the implementation of feedback with an automated process control system, can be carried out both with the help of a speed sensor and without it, using the computing power of a frequency converter included in the AED. For the sensorless AED to work in an automated process control system, it is necessary to ensure adequate restoration of the vector of state variables of the induction motor (IM) in the frequency converter using a configurable mathematical model. To restore the vector of state variables, it is necessary to select coefficients in the system of differential equations that correspond with some error to the electrical parameters of the BP replacement circuit, i.e. to carry out the identification procedure. In fact, the procedure for determining the parameters of the PS is the process of finding the extremum of the objective function, built on the basis of data obtained during the operation of the PS. In electrical engineering, numerical methods for finding the extremum of the objective function have become widely used to identify parameters, but these methods have significant limitations and disadvantages. The problem of using numerical methods to find the extremum of an objective function with two or more arguments in AED microprocessor control systems is that it is necessary to calculate partial derivatives in discrete form for each argument of the function. Calculation of partial derivatives in ideal systems without noise and disturbances is a proven and easy-to-implement process, but noise and disturbances are present in real microprocessor systems. Because of this, when calculating partial derivatives for each argument, the probability of breakpoints of the first and second kind increases, the struggle with which presents a certain difficulty. One of the classes of methods that allow determining the extremum of an objective function without finding partial derivatives are metaheuristic algorithms, and in particular genetic algorithms. Aim of research Experimental study of the efficiency of a genetic algorithm in the problem of dynamic identification of parameters of an induction motor circuit with an open rotor winding without stopping and decommissioning an electrical complex. Research methods Metaheuristic algorithms, iterative procedures, genetic algorithm, discrete systems, optimization methods. Results The effectiveness of the genetic algorithm was experimentally tested and proved in the problem of dynamic identification of parameters of the induction motor replacement circuit with an open rotor winding without stopping and decommissioning the electrical complex.

A fuzzy set theory-based fast fault diagnosis approach for rotators of induction motors.

Induction motors have been widely used in industry, agriculture, transportation, national defense engineering, etc. Defects of the motors will not only cause the abnormal operation of production equipment but also cause the motor to run in a state of low energy efficiency before evolving into a fault shutdown. The former may lead to the suspension of the production process, while the latter may lead to additional energy loss. This paper studies a fuzzy rule-based expert system for this purpose and focuses on the analysis of many knowledge representation methods and reasoning techniques. The rotator fault of induction motors is analyzed and diagnosed by using this knowledge, and the diagnosis result is displayed. The simulation model can effectively simulate the broken rotator fault by changing the resistance value of the equivalent rotor winding. And the influence of the broken rotor bar fault on the motors is described, which provides a basis for the fault characteristics analysis. The simulation results show that the proposed method can realize fast fault diagnosis for rotators of induction motors.

CONSTRUCTION AND PERFORMANCE EVALUATION OF TWO STAGED THREE BLADED SAVONIUS VERTICAL AXIS WIND ENERGY CONVERSION SYSTEM

This study is intended to increase the rotor performance of the Savonius wind rotor, by increasing the numbers of blades of the already existing two blades Savonius vertical axis wind turbines (VAWTs) to three which was designed to increase the Savonius wind rotor performance. Two stage three bladed wind turbine system has been designed and constructed. The system was made up of six split drums which were welded together to form a concave shape to capture wind from all directions, with a shaft to pass through the midst of the welded drums which was then mounted on a tower of about 15 m high, which in turn will cause the rotor to rotate. This was then connected to a 12 V Generator. The wind turbine converts the kinetic energy available in the wind to produce electricity, using the Generator with output power of 60 W. The results obtained showed that the system was able to accept wind from any direction and commenced rotation as soon as the wind speed of 3.3 m/s (cut in) was available at the site. The minimum and maximum power outputs of 5.14 W and 13.34 W, corresponding to wind speeds of 7.2 m/s and 9.4.5 m/s were recorded respectively. Similarly, for a rotation per minute of 811 rpm a voltage of 7.14 V was generated. Hence for a two stages three blades Savonius the performance was 12.2 %, as against a single stage two blades Savonius whose performance was 7%, a deviation of 5.2 %.

Performance Improvement of Induction Motor Controlled by Thyristor Chopper on the Rotor Side

In this paper, the performance characteristics of a variable-speed drive system with a wound rotor induction motor incorporating a 3-phase diode bridge rectifier - thyristor chopper with a modified commutation circuit system on the rotor side were studied. A DC equivalent circuit was used in the analysis of the motor-rectifier-chopper system and suitable equations have been derived for the determination of the system performance. The analytical results obtained are compared with those obtained experimentally to ascertain the validity of the system in practical applications. The results obtained indicate that a true variable speed drive system based on a thyristor chopper-controlled induction motor is successfully implemented. It is shown that the thyristor chopper control using the Hitachi commutation circuit permits the realization of a slip-ring induction motor as a variable speed and improved power factor. Also, the torque level obtained by the chopper control was found to be three times that obtained from conventional rotor resistance control at the same conditions.

Speed estimation of a Doubly Fed Induction Machine controlled by a Field Oriented Control Strategy

This paper studies the estimation problem of speed in a Doubly Fed Induction Machine (DFIM) controlled by a Field Oriented Control (FOC) Strategy. The DFIM is the most responsive in variable speed. The chosen configuration uses two voltage inverters connected to the stator and rotor windings, to adopt the power distribution between them through the pulses distribution of the stator and the rotor in motor operating mode. It is necessary to model the DFIM in three-phase equations and then in two-phase equations faithfully representing the characteristics of the machine. From this model, we can design and simulate the control. The control by oriented rotor flux can be realized by using the speed provided by sensors or estimators. In this paper, we have used the Extended Kalman Filter (EKF) in order to avoid problems caused by the motor speed sensor and improve the robustness of the control and its performance without using any speed sensor.

Starting winding parameters influence on starting characteristics of salient-pole synchronous motor

The asynchronous method of starting a salient-pole synchronous motor (SPSM), its starting characteristics, which are the dependence of the current I of the stator and the electromagnetic moment M to the slip s at constant stator winding feed voltage U and frequency f have been analyzed. A mathematical model that considers magnetic and electrical asymmetry was designed. The magnetic asymmetry of the SPSM is cased by the salient-pole structure of the rotor, and the electric - due to the different number of windings along the longitudinal and transverse axes. To consider the magnetic and electrical asymmetry of SPMS carry out the following transformations: 1) replacing of the three-phase stator winding with two-phase, where the magnetic axis of one of the windings coincides with the longitudinal axis d, and the magnetic axis of the second winding - with the transverse axis q of the fixed coordinate of the orthogonal system dq; 2) the starting short-circuited winding is replaced by two windings: a longitudinal starting winding, the magnetic axis of which coincides with the d-axis, and a transverse starting winding, the magnetic axis of which coincides with the q-axis; 3) the movable rotor of the engine is considered stationary. The developed mathematical model showed that the starting properties of SPSM and the type of its starting characteristics depend on both: the parameters of the stator windings and the parameters of the rotor windings - the starting winding and the excitation windings. During the SPSM design process, the specified starting properties can be achieved by the variation of the starting winding parameters, which depend on the number of rods, sizes, and materials of rod and short-rings, as well as the size (width and height) of the slot groove. A computer program for calculating its starting characteristics with a given set of parameters for researching SPSM according to the described mathematical model was developed.