Adaptive variable structure control law for a variable speed wind turbine

Presentado en el 13th WSEAS International Conference on Automatic Control, Modelling and Simulation, ACMOS'11

Variable structure control for maximum wind power extraction

EuroPES 2009

Sliding mode control law for a variable speedwind turbine

Modern wind turbines are designed in order to work in variable speed operations. To perform this task, wind turbines are provided with adjustable speed generators, like the double feed induction generator. One of the main advantage of adjustable speed generators is improving the system efficiency compared to fixed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. An integral sliding surface is used, because the integral term avoids the use of the acceleration signal, which reduces the high frequency components in the sliding variable. The proposed design also uses the vector oriented control theory in order to simplify the generator dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and parameter uncertainties by using the Lyapunov stability theory. Finally simulated results show, on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, that usually appear in real systems.

Sliding Mode Control Strategy for Wind Turbine Power Maximization

The efficiency of the wind power conversions systems can be greatly improved using an appropriate control algorithm. In this work, a sliding mode control for variable speed wind turbine that incorporates a doubly fed induction generator is described. The electrical system incorporates a wound rotor induction machine with back-to-back three phase power converter bridges between its rotor and the grid. In the presented design the so-called vector control theory is applied, in order to simplify the electrical equations. The proposed control scheme uses stator flux-oriented vector control for the rotor side converter bridge control and grid voltage vector control for the grid side converter bridge control. The stability analysis of the proposed sliding mode controller under disturbances and parameter uncertainties is provided using the Lyapunov stability theory. Finally simulated results show, on the one hand, that the proposed controller provides high-performance dynamic characteristics, and on the other hand, that this scheme is robust with respect to the uncertainties that usually appear in the real systems.

A robust position control for induction machines

ICEM 2010

A Real-Time Sliding Mode Control for a Wind Energy System Based on a Doubly Fed Induction Generator

In this paper, a real time sliding mode control scheme for a variable speed wind turbine that incorporates a doubly feed induction generator is described. In this design, the so-called vector control theory is applied, in order to simplify the system electrical equations. The proposed control scheme involves a low computational cost and therefore can be implemented in real-time applications using a low cost Digital Signal Processor (DSP). The stability analysis of the proposed sliding mode controller under disturbances and parameter uncertainties is provided using the Lyapunov stability theory. A new experimental platform has been designed and constructed in order to analyze the real-time performance of the proposed controller in a real system. Finally, the experimental validation carried out in the experimental platform shows; on the one hand that the proposed controller provides high-performance dynamic characteristics, and on the other hand that this scheme is robust with respect to the uncertainties that usually appear in the real systems.

Robust speed control for a variable speed wind turbine

Modern wind turbines are designed in order to work in variable speed opera-tions. To perform this task, these turbines are provided with adjustable speed generators, like the double feed induction generator (DFIG). One of the main advantages of adjustable speed generators is improving the system efficiency compared with _xed speed generators, because turbine speed can be adjusted as a function of wind speed in order to maximize the output power. However, this system requires a suitable speed controller in order to track the optimal reference speed of the wind turbine. In this work, a sliding mode control for variable speed wind turbines is proposed. The proposed design also uses the vector oriented control theory in order to simplify the DFIG dynamical equations. The stability analysis of the proposed controller has been carried out under wind variations and pa-rameter uncertainties using the Lyapunov stability theory. Finally, the simulated results show on the one hand that the proposed controller provides a high-performance dynamic behavior, and on the other hand that this scheme is robust with respect to parameter uncertainties and wind speed variations, which usually appear in real systems.

Sliding mode control strategy for variable speed wind turbines

EFTA 2009

On the Benefits of Including Age-structure in Harvest Control Rules

This paper explores the benefits of including age-structure in the control rule (HCR) when decision makers regard their (age-structured) models as approximations. We find that introducing age structure into the HCR reduces both the volatility of the spawning biomass and the yield. Although at a fairly imprecise level the benefits are lower, there are still major advantages for actual assessment precision of the case study. Moreover, we find that when age-structure is included in the HCR the relative ranking of different policies in terms of variance in biomass and yield does not differ. These results are shown both theoretically and numerically by applying the model to the Southern Hake fishery.

The effect of firm-level contracts on the structure of wages: evidence from matched employer-employee data

Revised: 2006-11

The Cryo-EM Structure of a Complete 30S Translation Initiation Complex from Escherichia coli

11 p.

Global pressures, specific responses: effects of nutrient enrichment in streams from different biomes

13 p. + 2 p. (Erratum)

An adaptive sliding mode control law for the power maximization of the wind turbine system

POWERENG 2011

Análisis de prestaciones de variador de frecuencia Sinamics para el control de velocidad y posición.

[ES]En este documento se exponen los resultados de las diferentes funcionalidades analizadas del variador de frecuencia Sinamics G120. El dispositivo se ha configurado mediante el software de control TIA Portal para la realización de tareas de control de velocidad de un motor de inducción, así como el control de posición del eje del motor y de un eje lineal acoplado al mismo.

The Spanish corporate structure through interlocking directorates

[EN] The aim of this paper is to determine to what extent globalization pressures are changing interlocking directorate networks modeled on continental capitalism into Anglo-Saxon models. For this purpose we analyse the Spanish network of interlocks, comparing the present structure (2012) with that of 1993 and 2006. We show how, although Spanish corporative structure continues to display characteristics of the continental economies, some major banks are significantly reducing industrial activity. Nevertheless, the financial organizations continue to maintain a close relationship with sectors such as construction and services. The analysis of the network of directorates shows a retreat in activity of industrial banking in Spain. Two large Spanish financial institutions, BSCH and La Caixa, continue to undertake activities of industrial banking in 2006, but this activity is significantly reduced in 2012. According to the theories on the role of the interlocking directorates, the companies in these sectors assure their access to banking credit by incorporating advisors from financial organizations to their board of directors. We cannot conclude that the structure of the Spanish corporate network has become a new case of Anglo-Saxon structure, but we got indications that are becoming less hierarchic as banks seem to slowly abandon centrality positions. This is especially salient if we compare the networks of 2006 and 2012, which show a continuing decrease of the role of banks and insurance companies in the network.