Dual Stator-winding Induction Generator Research Articles

Dynamic-Decoupled Current Control Based on Reduced-Order Observer for Dual Stator-Winding Induction Generator

Dynamic-Decoupled Current Control Based on Reduced-Order Observer for Dual Stator-Winding Induction Generator

Linear Active Disturbance Rejection Control for Dual-Stator Winding Induction Generator AC Power System

In this article, a control strategy based on linear active disturbance rejection control (LADRC) is proposed for the dual-stator winding induction generator (DWIG) ac power system, in order to solve the problems of contradiction between tracking ability and dynamic performance with proportional-integral controller. Based on the rotor-flux-oriented coordinate system, the dynamic mathematic model of the output ac voltage of power winding (PW) is established. The load disturbance on the PW side and the variation of the system parameters are regarded as the total disturbance, which is observed and compensated by linear extended state observer (LESO) and linear state error feedback (LSEF), respectively. By analyzing the swiftness and disturbance-rejection ability with different bandwidths of LESO, the ac voltage LADRC controller is first designed for DWIG. The stability and performance analysis with different controller parameters is given and the robustness of the proposed controller under the parameter mismatch is investigated. Both simulation and experiments show that the proposed LADRC has a better tracking ability and dynamic performance. Moreover, the proposed LADRC also has strong robustness under the parameter mismatch.

Analysis of Spontaneous and Implicit Internal Self-Excitation in Aircraft Variable Frequency AC Power System Based on Dual-Stator Winding Induction Generator

The dual-stator winding induction generator (DWIG) is an alternative main generator in a variable frequency ac power system. So far, the existing studies have not covered the issue of DWIGs excitation controllability, which is a matter of importance for airworthiness. In this article, we develop an impedance-based modeling and analysis technique to investigate DWIGs excitation controllability. Two related topics are presented: the spontaneous self-excitation analysis in uncontrolled system and the implicit internal self-excitation pattern analysis in actively controlled system. In the topic about spontaneous self-excitation, a virtual impulse source technique is developed to derive the impedance-based method properly in the analysis for uncontrolled DWIG. In the second topic, the analysis performed in the presence of a closed-loop controller figures out the same underlying mechanism in both the plant's open-loop stability and the spontaneous self-excitation. The experimental results verify the proposed analysis and techniques that benefit the comprehensive understanding and practical application of DWIG-based power system.

Dual Stator Winding Induction Generator (DSWIG) used for hybrid micro grid power systems

This paper proposes a hybrid micro grid system for critical consumers like military disaster intervention, health or municipality. The solution is based on a multiple level of redundancy DC micro grid. The solution is projected to provide critical functionalities like stability, power quality, coordinated control, grid support capability. The configuration described here takes in consideration the problem integration of renewable energy sources which should have features like redundancy, flexibility and scalability from architecture point of view.

Dual Stator Winding Induction Generator (DSWIG) used as base Source in Hybrid Power Systems when Lost the Power

In this paper we propose a completely new solution in which the diesel generator is replaced by agas turbine that drives a dual stator winding induction generator (DSWIG), which can operate in a wide rangeof speeds, thus enabling maximization the efficiency of the gas turbine utilization according to the powerrequirements of the critical supply network.

Closed-Loop Dynamic Control for Dual-Stator Winding Induction Generator at Low Carrier Ratio With Selective Harmonic Elimination Pulsewidth Modulation

In this article, we present a closed-loop dynamic control scheme for a dual-stator winding induction generator (DWIG) with selective harmonic elimination pulsewidth modulation (SHEPWM). This control scheme can be applied in a variable-frequency ac power system based on the DWIG, which is able to operate in low-carrier-ratio conditions, especially in high-power aeroapplications. Common closed-loop induction machine control schemes, such as vector control strategy, generally lead to control failure with SHEPWM implemented. This proposed closed-loop dynamic control scheme makes the dynamic operation of the DWIG power system feasible with SHEPWM. The scheme consists of three main parts: the complex-signal observer for DWIG, outer loop controller for DWIG, and stator flux-linkage trajectory tracking controller. The complex-signal observer provides the extra steady-state components of control signals by using the complex coefficient filter. The outer loop controller provides the dynamic commands for control signals. Finally, the flux-linkage trajectory tracking control (FTTC) synthesizes these signals and serves as the inner loop. The simulation and experimental results verify the validity and effectiveness of the proposed scheme.

Control-Winding Direct Power Control Strategy for Five-Phase Dual-Stator Winding Induction Generator DC Generating System

A control-winding direct power control (CWDPC) strategy for a dc generating system based on the five-phase dual-stator winding induction generator is proposed and investigated in this article. For this generator, the flux-oriented control is usually employed in the previous work mainly for the sake of good static performance. However, the present control strategy has the limitation of the further enhancement of the dynamic properties. This article explores a CWDPC strategy to upgrade the dynamic performance of this generating system. The fundamental active power of the five-phase control winding (CW) relates to its dc bus voltage while the dc bus voltage on the five-phase power-winding (PW) side is related to the control of five-phase CW fundamental reactive power. By replacing inner current loops to power control loops, the CW instantaneous fundamental active and reactive powers are calculated through the power observer and regulated directly through two power-control loops. In the transient process, the CW fundamental active power changes slightly while the reactive power can be quickly controlled for fast recovery of the dc bus voltage on the five-phase PW side. As the system has an additional control degree of freedom, the third harmonic is also considered in the proposed strategy, and the corresponding implementation is given as well. The simulation and experimental results demonstrate that using the proposed CWDPC strategy, the system has shorter transient time and lower voltage change in the dynamic response than the flux-oriented control strategy, which means the dynamic performance is further improved.

A Dual-Stator Winding Induction Generator Based Wind-Turbine Controlled via Super-Twisting Sliding Mode

The dual-stator winding induction generator (DWIG) is a promising electrical machine for wind energy conversion systems, especially in the low/mid power range. Based on previous successful results utilising feed forward control, in this article, a super-twisting (ST) sliding mode improved control set-up is developed to maximise power extraction during low wind regimes. To accomplish this objective, via constant volts/hertz implementation, a ST controller was designed to command the DWIG control winding, such that the tip-speed ratio is robustly maintained at its optimal value. The proposed super-twisting control set-up was experimentally assessed to analyse its performance and to verify its efficiency in an actual generation test bench. The results showed a fast convergence to maximum power operation, avoiding chattering and offsets due to model uncertainties.

Control of Five-Phase Dual Stator-Winding Induction Generator With an Open Phase

Dual stator-winding induction generator (DWIG) is attractive in stand-alone power systems, and the aim of this paper is to develop the dc generating system of five-phase DWIG with an open phase. First, the relationship between flux and torque is constructed based on the reduced-order transformation, modified flux, and current. Second, the relation between modified voltage and current on the dq plane is constructed. The current of fundamental plane is used for the control loop of the power-winding voltage and control-winding voltage, respectively. Third, the current of the modified secondary subspace plane is used to control the five-phase DWIG operation at minimum control-winding loss. Finally, the simulation and experimental results are given to verify that the amplitude of phase current and output voltage can be regulated effectively by the proposed control strategy.

Application of Boost Converter to Increase the Speed Range of Dual-Stator Winding Induction Generator in Wind Power Systems

In this paper, a topology using a dual-stator winding induction generator (DWIG) and a boost converter is proposed for the variable speed wind power application. At low rotor speeds, the generator saturation limits the voltage of the DWIG. Using a boost converter, higher dc voltage can be produced while the DWIG operates at maximum power point tracking even at low-speed and low-voltage conditions. Semiconductor excitation controller (SEC) of the DWIG utilizes control-winding voltage oriented control method to adjust the voltage, considering V/f characteristics. For the proposed topology, the SEC capacity and the excitation capacitor are optimized by analyzing the SEC reactive current considering wind turbine power-speed curve, V/f strategy, and the generator parameters. The method shows that the per-unit capacity of the SEC can be limited to the inverse of DWIG magnetizing reactance per-unit value. The topology is simulated in MATLAB/Simulink platform and experimented with a scaled 1 kW prototype. Both simulation and experimental results demonstrate wide variable speed operation range of the DWIG and verify the optimization.

Optimal-Third-Harmonic-Injection-Based Control for a Five-Phase Dual Stator-Winding Induction Generator DC Generating System

This paper presents a third-harmonic optimization method for a five-phase dual stator-winding induction generator (FPDWIG). In this generator, a cage-type rotor is used, and there are two sets of five-phase stator windings. Based on the principle of nonsinusoidal power supply, the third harmonic is injected and optimized. By minimizing the cost function of the oscillation of flat level of air-gap flux density, the optimal ratio of the third harmonic is determined to make the waveform of the air-gap flux density flat-topped for better core utilization. The corresponding implementation based on the control-winding flux-oriented control with the consideration of different load conditions is given, as well. The simulation and experimental results verify the correctness and validity of the proposed optimization method, and by using this method, the desired air-gap flux density can be obtained, and the output power of the FPDWIG can be increased.

Recent Advances and Developments in Dual Stator-Winding Induction Generator and System

Dual stator-winding induction generator (DWIG) is one kind of emerging multiport electrical machine. It has become a promising direction in the last two decades, especially for stand-alone power systems and renewable energy power systems. This paper mainly focuses on the DWIG with similar-poles stator windings and cage-type rotor. An overview of DWIG and its system is given. Recent advances of this generator in system topologies, mathematical model, optimal design, control strategies, and performance analysis are presented. The developments and potential applications of the DWIG-based system are also discussed.

A New Configuration of Dual Stator Induction Generator Employing Series and Shunt Capacitors

Doubly fed induction generators are suitable for systems having limited speed range as the overall control can be carried out by fractionally rated converters. However, brushes and slip-rings used in these generators reduce system reliability and demand greater maintenance. Dual stator winding induction generator (DSWIG), being brushless, removes this limitation. Two distributed windings are embedded in the stator and the rotor is squirrel-cage. One of the windings is interfaced to an uncontrolled rectifier and the other to a fractionally rated PWM converter. Uncontrolled rectifier degrades the power quality within the generation system. At the same time, reactive power demand in induction generators increases with loading. This paper deals with design and control of a standalone dc system based on DSWIG, where a combination of passive tuned filter and series capacitor is utilized to address the voltage regulation and power quality issue. Simulation results using MATLAB/Simulink and experimental results (obtained from a laboratory prototype) have been presented, compared, and discussed to demonstrate the effectiveness of the proposed alternative.

Control and Performance of Five-Phase Dual Stator-Winding Induction Generator DC Generating System

In this paper, the five-phase dual stator-winding induction generator dc generating system with the static excitation controller is presented, and two kinds of control strategies for this system are proposed. In this generator, the cage-type rotor is employed, and two sets of five-phase windings are placed in the stator, namely, the power winding and control winding. Using the instantaneous power theory, the control-winding-flux-oriented control (CWFOC) strategy without harmonic injection is obtained. To improve power density, the CWFOC with harmonic injection is proposed as well. For these two strategies, the detailed implementation is studied. The results (simulation and experiment) support the correctness and effectiveness of the proposed control strategies, and the corresponding results show that, using the CWFOC strategy with harmonic injection, the output power of this system can be improved by about 11%.

A New Optimal Current Control Technique for Dual Stator Winding Induction Generator

For remote area distribution networks, brushless generation systems have an edge due to their high reliability. Researchers have found dual stator winding induction generator (DSWIG) to be one of the suitable candidates for this purpose. This paper deals with a unique configuration of DSWIG, which facilitates simultaneous power flow through both the stator windings in extended speed range. Both the windings feed the same dc-bus through corresponding converters. A passively tuned filter across uncontrolled winding has been introduced to improve power quality and supply a part of the reactive power based on an optimization criterion to maximize active power output from the system. A new index called “power sharing ratio” is introduced and a control strategy to distribute power through both the windings is proposed. An algorithm to find the “optimum power sharing ratio” is developed. This is based on maximum output per ampere of winding current. MATLAB/Simulink-based simulation studies have confirmed the efficacy of the control algorithm. Experimental investigations using a dSPACE 1103-based laboratory prototype have demonstrated the usefulness of the proposed system.

Asymmetrical Operation Analysis for Dual Stator-Winding Induction Generator Variable Frequency AC Generating System With Unbalanced Loads

In this paper, the performance of the dual stator-winding induction generator (DWIG) variable frequency ac (VFAC) generating system with unbalanced loads is analyzed, and an asymmetrical operation analysis method based on a three-port load network model is proposed. This method has four key steps: (1) deriving the three-port load network model for three-phase four-line unbalanced loads; (2) establishing the positive sequence, negative sequence, and zero sequence equivalent circuits for the DWIG; (3) combining the above model and circuits together to obtain the system whole equivalent model; and (4) writing the corresponding equations and solving them. The experimental results and the calculation results are almost consistent, which proves that the proposed method is correct and valid, and the DWIG VFAC generating system with unbalanced loads has a good performance.

Variable‐speed wind energy conversion system based on a dual stator‐winding induction generator

This study presents a wind energy conversion system based on a dual stator-winding induction generator. The generator can work at variable wind speed and can also be connected to the grid. The proposed energy conversion system presents three operation zones that depend on the wind speed and are delimited by the power ratio assigned to each of the two stator windings. The generator design starts from a three-phase squirrel-cage induction machine and allows a simple assembling of the new windings, what results in an economical, robust and reliable machine. These features make the generator appropriate for wind energy conversion systems located in remote places or in developing areas with limited resources, as well as for distributed generation systems and microgrids. This report also includes experimental and simulation results of the generator operation in the three working areas.

Analysis, Comparison, and Discussion of Control Strategies for Dual Stator-Winding Induction Generator DC Generating System

This paper presents four types of control strategies for a dual stator-winding induction generator dc generating system as well as their analysis, comparison, and discussion. These four types of control strategies include control-winding flux orientation control, control-winding voltage orientation control, control-winding direct power control, and instantaneous slip frequency control (ISFC). The ISFC strategy is described in detail for first employed in dc generating application, and the other strategies are briefly introduced and their performances are also summarized for comparison. The characteristics of control strategies are compared from four aspects: 1) system performance; 2) key components; 3) control principles; and 4) applications. From the comparison results, it can be inferred that all these four types of control strategies have some advantages, especially the ISFC. They can find suitable applications.

Grid-Connected Dual Stator-Winding Induction Generator Wind Power System for Wide Wind Speed Ranges

This paper presents a grid-connected dual stator-winding induction generator (DWIG) wind power system suitable for wide wind speed ranges. The parallel connection via a unidirectional diode between dc buses of both stator-winding sides is employed in this DWIG system, which can output a high dc voltage over wide wind speed ranges. Grid-connected inverters (GCIs) do not require booster converters; hence, the efficiency of wind energy utilization increases, and the hardware topology and control strategy of GCIs are simplified. In view of the particularities of the parallel topology and the adopted generator control strategy, we propose a novel excitation–capacitor optimization solution to reduce the volume and weight of the static excitation controller. When this excitation–capacitor optimization is carried out, the maximum power tracking problem is also considered. All the problems are resolved with the combined control of the DWIG and GCI. Experimental results on the platform of a 37 kW/600 V prototype show that the proposed DWIG wind power system can output a constant dc voltage over wide rotor speed ranges for grid-connected operations and that the proposed excitation optimization scheme is effective.

Wide-Speed-Range-Operation Dual Stator-Winding Induction Generator DC Generating System for Wind Power Applications

This paper presents a wide-speed-range-operation dual stator-winding induction generator (DWIG) dc generating system for wind power applications. In this system, the dc bus on the control-winding side and the dc bus on the power-winding side are connected in parallel to further widen the speed range of the constant dc voltage output, especially at low speeds. Based on the control mechanism of the DWIG and the instantaneous power theory, a control-winding-flux-orientation control strategy is employed. In order to improve the wind energy conversion efficiency at low wind speeds, the generator efficiency optimization method is investigated. The experimental results from a 20 kW/600 V prototype show that the proposed generating system can output the constant dc voltage in a speed range of 1:4, and the generator efficiency in the low speed range is improved, which both bring the advantages for wind power applications, such as expanding the scope of the wind energy utilization and capturing much more wind energy.