Showing papers on "Rotor (electric) published in 2013"
TL;DR: A novel sliding-mode observer is built according to the back electromotive force model after the back EMF equivalent signal is obtained, and low-pass filter and phase compensation module is eliminated and estimation accuracy is improved.
Abstract: This paper proposes a novel sliding-mode observer (SMO) to achieve the sensorless control of permanent-magnet synchronous motor (PMSM). An observer is built according to the back electromotive force (EMF) model after the back EMF equivalent signal is obtained. In this way, not only are low-pass filter and phase compensation module eliminated, but also estimation accuracy is improved. Numerical simulations and experiments with an 11-kW low-speed PMSM are carried out. The results demonstrate that the novel SMO can effectively estimate rotor position and speed and achieve good static and dynamic performance.
458 citations
TL;DR: A new flux-linkage-tracking-based low-voltage ride-through (LVRT) control strategy is proposed to suppress the short-circuit rotor current in doubly fed induction generator (DFIG)-based wind energy conversion systems (WECSs).
Abstract: For doubly fed induction generator (DFIG)-based wind energy conversion systems (WECSs), large electromotive force will be induced in the rotor circuit during grid faults. Without proper protection scheme, the rotor side of DFIG will suffer from overcurrents, which may even destroy the rotor-side converter (RSC). To mitigate this problem, a new flux-linkage-tracking-based low-voltage ride-through (LVRT) control strategy is proposed to suppress the short-circuit rotor current. Under the proposed control strategy, the rotor flux linkage is controlled to track a reduced fraction of the changing stator flux linkage by switching the control algorithm of RSC during grid faults. To validate the proposed control strategy, a case study of a typical 1.5-MW DFIG-based WECS is carried out by simulation using the full-order model in SIMULINK/SimPowerSystems. In the case study, a comparison with a typical LVRT method based on RSC control is given, and the effect of the control parameter on the control performance is also investigated. Finally, the validity of the proposed method is further verified by means of laboratory experiments with a scaled-size DFIG system.
219 citations
TL;DR: In this paper, a low voltage ride through (LVRT) control scheme is proposed to enhance the ability of reactive power support of a doubly fed induction generator (DFIG) based wind turbine during serious voltage dips.
Abstract: The paper presents a new control strategy to enhance the ability of reactive power support of a doubly fed induction generator (DFIG) based wind turbine during serious voltage dips. The proposed strategy is an advanced low voltage ride through (LVRT) control scheme, with which a part of the captured wind energy during grid faults is stored temporarily in the rotor's inertia energy and the remaining energy is available to the grid while the DC-link voltage and rotor current are kept below the dangerous levels. After grid fault clearance, the control strategy ensures smooth release of the rotor's excessive inertia energy into the grid. Based on these designs, the DFIG's reactive power capacity on the stator and the grid side converter is handled carefully to satisfy the new grid code requirements strictly. Simulation studies are presented and discussed.
217 citations
TL;DR: In this article, the performance of a Savonius wind turbine with constant cross-sections is examined by means of quasi 2D flow predictions executed in ANSYS CFX, in a way that allows comparison with wind tunnel data presented in a related paper.
217 citations
TL;DR: In this article, an acoustic Doppler velocimeter and a torque transducer were used to simultaneously measure the three velocity components of the flow at various locations upstream of the turbine and in the wake region and turbine power, respectively.
Abstract: A laboratory experiment was performed to study the dynamically rich interaction of a turbulent open channel flow with a bed-mounted axial-flow hydrokinetic turbine. An acoustic Doppler velocimeter and a torque transducer were used to simultaneously measure at high temporal resolution the three velocity components of the flow at various locations upstream of the turbine and in the wake region and turbine power, respectively. Results show that for sufficiently low frequencies the instantaneous power generated by the turbine is modulated by the turbulent structure of the approach flow. The critical frequency above which the response of the turbine is decoupled from the turbulent flow structure is shown to vary linearly with the angular frequency of the rotor. The measurements elucidate the structure of the turbulent turbine wake, which is shown to persist for at least fifteen rotor diameters downstream of the rotor, and a new approach is proposed to quantify the wake recovery, based on the growth of the largest scale motions in the flow. Spectral analysis is employed to demonstrate the dominant effect of the tip vortices in the energy distribution in the near-wake region and uncover meandering motions.
206 citations
01 Jan 2013
TL;DR: In this article, a modeling framework is proposed and validated to simulate turbine wakes and associated power losses in wind farms, which combines the large-eddy simulation (LES) technique with blade element theory and a turbine-model-specific relationship between shaft torque and rotational speed.
Abstract: A modeling framework is proposed and validated to simulate turbine wakes and associated power losses in wind farms. It combines the large-eddy simulation (LES) technique with blade element theory and a turbine-model-specific relationship between shaft torque and rotational speed. In the LES, the turbulent subgrid-scale stresses are parameterized with a tuning-free Lagrangian scale-dependent dynamic model. The turbine-induced forces and turbine-generated power are modeled using a recently developed actuator-disk model with rotation (ADM-R), which adopts blade element theory to calculate the lift and drag forces (that produce thrust, rotor shaft torque and power) based on the local simulated flow and the blade characteristics. In order to predict simultaneously the turbine angular velocity and the turbine-induced forces (and thus the power output), a new iterative dynamic procedure is developed to couple the ADM-R turbine model with a relationship between shaft torque and rotational speed. This relationship, which is unique for a given turbine model and independent of the inflow condition, is derived from simulations of a stand-alone wind turbine in conditions for which the thrust coefficient can be validated. Comparison with observed power data from the Horns Rev wind farm shows that better power predictions are obtained with the dynamic ADM-R than with the standard ADM, which assumes a uniform thrust distribution and ignores the torque effect on the turbine wakes and rotor power. The results are also compared with the power predictions obtained using two commercial wind-farm design tools (WindSim and WAsP). These models are found to underestimate the power output compared with the results from the proposed LES framework.
189 citations
TL;DR: Simulation and experimental results show the validity of the proposed method, leading to an effective diagnosis procedure for both stator and rotor electrical faults in WRIMs, and proves the importance of the fault components computed from rotor voltages in comparison to those coming from rotor currents under closed-loop operation.
Abstract: The aim of this paper is to present a diagnosis methodology for the detection of electrical faults in three-phase wound-rotor induction machines (WRIMs). In the considered application, the rotor windings are supplied by a static converter for the control of active and reactive power flows exchanged between the machine and the electrical grid. The proposed diagnosis approach is based on the use of wavelet analysis improved by a preprocessing of the rotor-voltage commands under time-varying conditions. Thus, the time evolution of fault components can be effectively analyzed. This paper proves also the importance of the fault components computed from rotor voltages in comparison to those coming from rotor currents under closed-loop operation. A periodical quantification of the fault, issued from the wavelet analysis, has been introduced for accurate stator- or rotor-fault detection. Simulation and experimental results show the validity of the proposed method, leading to an effective diagnosis procedure for both stator and rotor electrical faults in WRIMs.
181 citations
TL;DR: In this article, an experimental investigation of an alternative fault-ride-through approach using a brake chopper circuit across the converter dc link to ensure that the dc-link voltage remains under control during a fault is presented.
Abstract: The performance of the doubly fed induction generator (DFIG) during grid faults is attracting much interest due to the proliferation of wind turbines that employ this technology. International grid codes specify that the generator must exhibit a fault-ride-through (FRT) capability by remaining connected and contributing to network stability during a fault. Many DFIG systems employ a rotor circuit crowbar to protect the rotor converter during a fault. Although this works well to protect the generator, it does not provide favorable grid support behavior. This paper describes an experimental investigation of an alternative FRT approach using a brake chopper circuit across the converter dc link to ensure that the dc-link voltage remains under control during a fault. Two different approaches to chopper control are examined and the resulting FRT performance is compared with that of a conventional crowbar approach. The new chopper-based control methods are experimentally evaluated using a 7.5-kW DFIG test rig facility.
181 citations
TL;DR: Experimental results are shown to confirm the effectiveness of the proposed method and the convergence of the observer estimation error, and sufficient conditions are given to prove the practical stability.
Abstract: This paper proposes an adaptive interconnected observer for sensorless control of a synchronous motor. The corresponding observer is used to estimate the rotor speed, the rotor position, and the load torque and, moreover, to estimate the stator inductance and the stator resistance. The convergence of the observer estimation error is analyzed, and sufficient conditions are given to prove the practical stability. Experimental results are shown to confirm the effectiveness of the proposed method.
176 citations
TL;DR: In this article, a large-scale literature review of rotor-stator contacts with stators is presented, highlighting the phenomenology involved in different rotor to stator contacts configurations and confirming the great complexity of the problems which involve multiphysics and multiscale coupled behaviors.
163 citations
TL;DR: A concise yet comprehensive analysis and comparison of many different model-based algorithms that are able to estimate the wind speed using common turbine measurements, reviewing their advantages and drawbacks is presented.
Abstract: Modern wind turbine controllers use wind speed information to improve power production and reduce loads on the turbine components. The turbine top wind speed measurement is unfortunately imprecise and not a good representative of the rotor effective wind speed. Consequently, many different model-based algorithms have been proposed that are able to estimate the wind speed using common turbine measurements. In this paper, we present a concise yet comprehensive analysis and comparison of these techniques, reviewing their advantages and drawbacks. We implement these techniques and compare the results on both aero-servo-elastic turbine simulations and real turbine field experiments in different wind scenarios.
TL;DR: An online method for simultaneously estimating the winding resistance and rotor flux linkage of a PMSM is proposed, suitable for application under constant load torque and is finally verified on two prototype PMSMs and shows good performance.
Abstract: Winding resistance and rotor flux linkage are important to controller design and condition monitoring of a surface-mounted permanent-magnet synchronous machine (PMSM) system. In this paper, an online method for simultaneously estimating the winding resistance and rotor flux linkage of a PMSM is proposed, which is suitable for application under constant load torque. It is based on a proposed full-rank reference/variable model. Under constant load torque, a short pulse of id ≠ 0 is transiently injected into the d-axis current, and two sets of machine rotor speeds, currents, and voltages corresponding to id = 0 and id ≠ 0 are then measured for estimation. Since the torque is kept almost constant during the transient injection, owing to the moment of system inertia and negligible reluctance torque, the variation of rotor flux linkage due to injected id ≠ 0 can be taken into account by using the equation of constant torque without measuring the load torque and is then associated with the two sets of machine equations for simultaneously estimating the winding resistance and rotor flux linkage. Furthermore, the proposed method does not need the values of the dq-axis inductances, while the influence from the nonideal voltage measurement, which will cause an ill-conditioned problem in the estimation, has been taken into account and solved by error analysis. This method is finally verified on two prototype PMSMs and shows good performance.
TL;DR: The PSIM simulation and experimental results for a doubly-fed induction generator wind turbine system have proved the validity of the proposed MPPT algorithm, which takes advantage of the rotor inertia power.
Abstract: This paper proposes a new maximum power point tracking (MPPT) algorithm for variable-speed wind turbine systems, which takes advantage of the rotor inertia power. In this method, a proportional controller is added to the power control to effectively reduce the moment of inertia of the wind turbines, which can improve the fast performance of the MPPT control. The PSIM simulation and experimental results for a doubly-fed induction generator wind turbine system have proved the validity of the proposed algorithm.
TL;DR: The effects of Vienna rectifiers voltage vectors on instantaneous PMSG torque and stator flux are derived, and DTC of PMSG by the Vienna rectifier is implemented, considering the constraints imposed by theVienna rectifier.
Abstract: Vienna rectifier as generator-side converter of wind energy conversion system (WECS) using a permanent-magnet synchronous generator (PMSG) has several advantages compared to conventional back-to-back inverter, such as higher efficiency and improved total harmonic distortion. On the other hand, direct torque control (DTC) of the generator in WECS is of interest, particularly for low-power applications due to several merits, including fast torque response, insensitivity to PMSG model and associated parameters, elimination of rotor position sensor, and reduced computations. In this paper, the effects of Vienna rectifier voltage vectors on instantaneous PMSG torque and stator flux are derived, and DTC of PMSG by the Vienna rectifier is implemented, considering the constraints imposed by the Vienna rectifier. Experimental tests for a 1-kW prototype are presented, which confirm the simulations and theoretical results.
TL;DR: In this article, a five-year historical data set has been assembled for constructing the reference curves of wind power, rotor speed, and blade pitch angle, with wind speed as an input variable.
Abstract: Three different operational curves-the power curve, rotor curve, and blade pitch curve-are presented for monitoring a wind farm's performance. A five-year historical data set has been assembled for constructing the reference curves of wind power, rotor speed, and blade pitch angle, with wind speed as an input variable. A multivariate outlier detection approach based on k-means clustering and Mahalanobis distance is applied to this data to produce a data set for modeling turbines. Kurtosis and skewness of bivariate data are used as metrics to assess the performance of the wind turbines. Performance monitoring of wind turbines is accomplished with the Hotelling T2 control chart.
TL;DR: In this article, a complete Hill diagram was constructed and pressure-time measurements were performed at several operating conditions over the entire range of power generation by installing pressure sensors in the rotating and stationary domains of the turbine.
Abstract: Experimental and numerical studies on a high head model Francis turbine were carried out over the entire range of turbine operation. A complete Hill diagram was constructed and pressure-time measurements were performed at several operating conditions over the entire range of power generation by installing pressure sensors in the rotating and stationary domains of the turbine. Unsteady numerical simulations were performed at five operating conditions using two turbulent models, shear stress transport (SST) k-ω and standard k-e and two advection schemes, high resolution and second order upwind. There was a very small difference (0.85%) between the experimental and numerical hydraulic efficiencies at the best efficiency point (BEP); the maximum difference (14%) between the experimental and numerical efficiencies was found at lower discharge turbine operation. Investigation of both the numerical and experimental pressure-time signals showed that the complex interaction between the rotor and stator caused an output torque oscillation over a particular power generation range. The pressure oscillations that developed due to guide vanes and runner blades interaction propagate up to the trailing edge of the blades. Fourier analysis of the signals revealed the presence of a vortex rope in the draft tube during turbine operation away from the BEP.
TL;DR: In this paper, a robust μ-synthesis control scheme for structural resonance vibration suppression of high-speed rotor systems supported by active magnetic bearings (AMBs) in the magnetically suspended double-gimbal control moment gyro (MSDGCMG) was presented.
Abstract: This paper explores a robust μ-synthesis control scheme for structural resonance vibration suppression of high-speed rotor systems supported by active magnetic bearings (AMBs) in the magnetically suspended double-gimbal control moment gyro (MSDGCMG). The derivation of a nominal linearized model about an operating point was presented. Sine sweep test was conducted on each component of AMB control system to obtain parameter variations and high-frequency unmodeled dynamics, including the structural resonance modes. A fictitious uncertainty block was introduced to represent the performance requirements for the augmented system. Finally, D-K iteration procedure was employed to solve the robust μ-controller. Rotor run-up experiments on the originally developed MSDGCMG prototype show that the designed μ-controller has a good performance for vibration rejection of structural resonance mode with the excitation of coupling torques. Further investigations indicate that the proposed method can also ensure the robust stability and performance of high-speed rotor system subject to the reaction of a large gyro torque.
TL;DR: In this article, the main rules for the design of multilayer windings are illustrated, and it is also investigated if the adoption of a multi-layer winding makes possible the limitation of the torque ripple and the rotor losses of the machine.
Abstract: This paper deals with fractional-slot multilayer windings. They are becoming attractive since they allow reducing the harmonic content of the magnetomotive force. Some examples of such a type of windings are reported in the literature, but they are limited to a few slot/pole combinations. On the contrary, in this paper, a general theory is presented. The main rules for the design of multilayer windings are illustrated. It is also investigated if the adoption of a multilayer winding makes possible the limitation of the torque ripple and the rotor losses of the machine. Several examples and experimental tests are reported to investigate the advantages and the convenience of adopting multilayer windings.
TL;DR: In this article, a rolling bearing signal model is proposed based on the dynamic load analysis of a rotor bearing system, where the defect load on the surface of the bearing is divided into two parts, the alternate load and the determinate load.
TL;DR: Potential control complexity owing to the higher number of rotor poles, self-starting, and fault tolerance of the switched reluctance machine is investigated.
Abstract: Switched reluctance machine (SRM) has been viewed as a low-cost machine with concentrated windings on the stator and no magnetic source on the rotor. Owing to the higher torque-production capability with lower ripple, an SRM with a higher number of rotor poles is a potential candidate for traction applications in hybrid and plug-in hybrid electric vehicles. However, since external phase commutation and rotor-position detection are necessary to run the SRM, its control can be challenging. In case of an SRM with a higher number of rotor poles, each phase is energized more frequently in one revolution, and the current conduction time is shorter due to the smaller interpolar gap between rotor poles. This paper investigates potential control complexity owing to the higher number of rotor poles, self-starting, and fault tolerance of the machine. A 5-hp drivetrain with a three-phase 6/10 SRM has been developed for traction application. Conventional current and speed controls have been implemented to experimentally evaluate the dynamic performance of the new family of SRMs. It has been shown that the 6/10 SRM is capable of operating even if two of its phases develop a fault. Moreover, the 6/10 SRM is capable of starting by itself with an initial hard alignment when only two phases are operating.
TL;DR: In this article, an improved Hilbert method was proposed by conjugating the Hilbert transform and ESPRIT together to detect rotor bar faults in induction motors, where the estimation of signal parameters via rotational invariance technique (ESPRIT) was introduced to replace FFT.
Abstract: The traditional Hilbert method to detect broken rotor bar fault in induction motors is reviewed and its major drawbacks are clearly revealed, namely, deteriorating or even completely failing when a motor operating at low slip due to the fixed constraints of fast Fourier transform (FFT) is used in this method. To overcome this, the estimation of signal parameters via rotational invariance technique (ESPRIT) is then introduced to replace FFT, and an improved Hilbert method is thus presented by conjugating the Hilbert transform and ESPRIT together. Experimental results of a small motor in a laboratory and a large motor operating on an industrial site are reported to demonstrate the effectiveness of the improved Hilbert method.
TL;DR: A new control strategy for fault-tolerant operation of the R-FSPM motor drive considering the capability limitation of the power converter by injecting harmonic currents, the so-called remedial injected-harmonic-current (RIHC) operation mode is proposed.
Abstract: Redundant flux-switching permanent-magnet (R-FSPM) motors are a new class of brushless machines having magnets in the stator, offering high power density, simple and robust rotor structure, and good thermal dissipation conditions. This paper proposes a new control strategy for fault-tolerant operation of the R-FSPM motor drive considering the capability limitation of the power converter. The key is to operate the R-FSPM motor in the remedial mode by injecting harmonic currents, the so-called remedial injected-harmonic-current (RIHC) operation mode. Moreover, the motor losses at the existing and the proposed remedial operations are compared for evaluation. Both cosimulation and experimental results are presented, confirming that the proposed RIHC operation can offer good steady-state and dynamic performances while reducing the motor losses and the capability requirements of the power converter during fault.
TL;DR: In this article, a piezoelectric-driven stepping rotary actuator based on the inchworm motion is presented, which can realize large rotary ranges and high rotary speed with high accuracy.
Abstract: This paper presents a piezoelectric-driven stepping rotary actuator based on the inchworm motion. With the help of nine piezoelectric stacks and the flexure hinges, the designed actuator can realize large rotary ranges and high rotary speed with high accuracy. Three kinds of working units that compose the actuator are described and calculated: the clamping unit to hold the rotor, the adjusting unit to preload the piezoelectric stacks and the driving unit to produce the driving torque. To test the working performance, a prototype actuator was fabricated, and the experimental results indicate that the minimum stepping angle is 4.95 μrad when the driving voltage is 20 V and the frequency is 1 Hz, the maximum output torque is 93.1 N mm under the driving voltage of 100 V and the maximum velocity can be 6508.5 μrad/s when the frequency reaches 30 Hz. The experimental results verify that the proposed actuator can realize different stepping angles and rotation speeds with high accuracy under different driving voltages and frequencies.
TL;DR: In this article, a fluid-structure interaction (FSI) validation study of a wind turbine with CX-100 composite blades is presented, where a rotation-free isogeometric shell formulation is used to model the blade structure, while the aerodynamics formulation makes use of the FEM-based ALE-VMS method.
Abstract: A fluid–structure interaction (FSI) validation study of the Micon 65/13M wind turbine with Sandia CX-100 composite blades is presented. A rotation-free isogeometric shell formulation is used to model the blade structure, while the aerodynamics formulation makes use of the FEM-based ALE-VMS method. The structural mechanics formulation is validated by means of eigenfrequency analysis of the CX-100 blade. For the coupling between the fluid and structural mechanics domains, a nonmatching discretization approach is adopted. The simulations are done at realistic wind conditions and rotor speeds. The rotor-tower interaction that influences the aerodynamic torque is captured. The computed aerodynamic torque generated by the Micon 65/13M wind turbine compares well with that obtained from on-land experimental tests.
TL;DR: A novel omni-direction-guide-vane (ODGV) that surrounds a vertical axis wind turbine (VAWT) is designed to improve the wind turbine performance as mentioned in this paper.
TL;DR: In this article, the authors numerically explore the non-linear two-dimensional unsteady flow over a conventional Savonius rotor and a Bach-type rotor, and develop a simulation method for predicting their aerodynamic performance.
TL;DR: In this article, the influence of variation of Reynolds number and the overlap ratio on the performance of a modified Savonius rotor with aspect ratio of 1.57 at a Reynolds numbers equal to Re −=−79,794, Re−=−99,578, Re ≥116,064 and Re ≥147,059.
TL;DR: In this article, an aerodynamic performance of stationary and rotating Savonius rotor for various overlap ratios is numerically analyzed using four turbulence models, and the simulation is compared with the present and published experimental results to determine the suitable turbulence model.
TL;DR: The objective of this paper is to make a clear and rigorous characterization and classification of the harmonics present in a healthy cage rotor induction motor spectrum as a starting point for diagnosis.
Abstract: Before applying current-signature-analysis-based monitoring methods, it is necessary to thoroughly analyze the existence of the various harmonics on healthy machines. As such an analysis is only done in very few papers, the objective of this paper is to make a clear and rigorous characterization and classification of the harmonics present in a healthy cage rotor induction motor spectrum as a starting point for diagnosis. Magnetomotive force space harmonics, slot permeance harmonics, and saturation of main magnetic flux path through the virtual air-gap permeance variation are taken into analytical consideration. General rules are introduced giving a connection between the number of stator slots, rotor bars, and pole pairs and the existence of rotor slot harmonics as well as saturation-related harmonics in the current spectrum. For certain combinations of stator and rotor slots, saturation-related harmonics are shown to be most prominent in motors with a pole pair number of two or more. A comparison of predicted and measured current harmonics is given for several motors with different numbers of pole pairs, stator slots, and rotor bars.
TL;DR: In this paper, a 10-m diameter, 3-bladed horizontal axis tidal current turbine (HATCT) was designed for different blade location and the hydrodynamic characteristics of the hydrofoils were analyzed.