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An 80 kW `Proof of Concept' generator with 35 pole pair, surface mounted permanent magnet rotor, 60 tooth coils, fractional slot per pole per phase stator, air-cooled, synchronous generator has been built and tested. This paper documents laboratory tests performed in the GE Global Research Europe lab facility. The paper reports about testing and comparison to simulation tools. The main focus of the...
The combination of extensive cable networks and wind turbine converters has been identified as a potential cause of resonances. A modelling approach for a doubly fed induction generator and a full power converter fed generator for harmonic penetration studies is developed and discussed. An example offshore wind farm is then studied in the simulation package IPSA using the detailed wind turbine generator...
Current grid codes require the fault ride-through capability of modern wind turbines. During grid faults the reactive current control of the wind turbines should be used to support the grid voltage. With modern protection devices the fault durations are normally in a range of some hundred milliseconds or less. However this time window may be decisive for the stability of the conventional generators...
The control algorithms proposed in the literature so far for the Double Output Induction Machine Based Variable Speed Constant Frequency (VSCF) stand alone generators suffer from the disadvantage of loss of `field orientation' during sudden load disturbance at the machine terminal. As a result, undesirable transients are observed in the load voltage during such transients. This paper presents a new...
In this paper, a robust self-tuning fuzzy speed controller for direct torque control using space vector modulation (SVM) technique is proposed for the high performance drives of induction motor. The design of robust self-tuning fuzzy speed controller greatly affects the performance of Induction Motor (IM) fed with a Voltage Source Inverter (VSI). The performance of the proposed self-tuning Fuzzy PI...
Oscillation damping via variable speed wind generators have been addressed in literature. Among the techniques, active power modulation has been studied. However, active power is closely related with electromagnetic torque. Modulating active power can introduce oscillations in the torque. This is undesired. The objective of this paper is to study an alternative technique - reactive power modulation...
This paper presents the design and analysis of a direct-coupled radial-flux permanent magnet generator (PMG) for wind turbine applications. The analysis of the design was carried out using finite-element analysis (FEA). The design data is used in optimizing the configuration and magnetic flux density of the PMG. For evaluating the performance of the proposed PMG, the prototype generator is implemented...
In this paper a set PM machine designs with the same level output characteristics were studied. This study covers the influence of the various types of windings arrangements, varying the number of slots, and pole width as design parameters on the cogging torque, back EMF, flux linkages, total torque, and speed of PM motor. These parameters were 2D finite element solution. A phase variable model for...
In this paper, a novel systematic and efficient approach, using the fuzzy-based Taguchi method with multiple performance characteristics index (MPCI), is employed for obtaining the robust design of an in-wheel permanent-magnet (PM) motor with both lower torque ripple factor and higher efficiency. According to the geometric parameters of the PM motor, we select the controllable factors and their levels,...
The use of a series-connected self-excited synchronous generator for isolated distributed generation is investigated. Such a machine may be realized by connecting the stator and rotor windings of a slip-ring induction machine in series, but with reversed phase sequence. The advantage of the machine configuration is high power density and high-speed operation. Both phasor diagram and time-stepping...
Shorted stator induction generator (IG) is presented for low wind speed power application. An analytical model is derived for predicting electrical performance of the generator while operating in regions 1 and 2 of turbine power versus wind speed curve. This paper determines an explicit optimal stator electrical speed of operation since the stator is disconnected from synchronism with the grid. A...
This paper presents the magnetic suspension test results of a bearingless motor/generator for flywheel energy storage systems. A prototype bearingless motor/generator is built on the basis of the computed results by Finite Element Method (FEM). It is an outer rotor-type permanent magnet (PM) synchronous motor/generator and the rotor is wrapped by the flywheel (CFRP). Thus, the motor/generator, the...
This paper presents the simulated and measured results of switching transients of the laboratory Microgrid system of the companion paper in Part I that implements a web-based monitoring system using an industrial PLC and campus internet. The studied laboratory Microgrid system consists of two wind induction generators, an AC-to-DC converter, a DC-to-AC inverter, a PV module, a UPS, and a battery module,...
This paper proposes a new vector-based hysteresis current regulator (VBHCR) in the rotor-side converter of DFIG to enhance the control performance under unbalanced supply voltage condition. The “Γ-form” is used for the equivalent circuit of the machine to reduce the modeling complexity. This is followed by presenting the principle and practical implementation of the proposed VBHCR in the DFIG application...
The recently proposed power-synchronization control for grid-connected voltage-source converters (VSCs) has been shown to be a feasible solution for high-voltage dc (HVDC) transmission connected to high-impedance weak ac systems. In this paper, power-synchronization control is investigated for VSC-HVDC connected to another type of weak ac system, i.e., low-inertia or island systems. As an example,...
This paper first presents the Hopf bifurcation analysis for a vector-controlled doubly fed induction generator (DFIG) which is widely used in wind power conversion systems. Using three-phase back-to-back pulse-width-modulated (PWM) converters, DFIG can keep stator frequency constant under variable rotor speed and provide independent control of active and reactive power output. The oscillatory instability...
This paper presents a speed and position estimation method for the sensorless direct torque and flux control scheme for matrix converter driven interior permanent-magnet synchronous motor. The adaptive sliding mode observer simultaneously estimates the stator flux, speed and rotor position. A permanent magnet flux estimator is integrated with the observer to compensate the effect of inaccurate PM...
This paper proposes a combined protection and control strategy to enhance the low voltage ride-through (LVRT) capability of a wind turbine driven doubly fed induction generator (DFIG). Since the conventional crowbar is activated to protect the rotor side converter during the fault interval, the DFIG will operate in the fix speed mode and absorb large amount of reactive power from the grid. This problem...
A DFIG wind turbine is a variable-speed wind turbine widely used in modern wind power industry. The maximum power extraction of the turbine is affected by (1) electrical characteristics of the generator, (2) aerodynamic characteristics of the turbine blades, and (3) maximum power extraction control strategies. This paper presents a DFIG maximum power extraction study through integrated steady-state...
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