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The purpose of this paper is to provide a new theory of adjustable speed decoupled generation which has the potential to challenge existing coupled generation based on a classical synchronous generator operating with fixed speed.

The paper's approach is a theoretical consideration of the drawbacks of conventional fixed speed generation based on a synchronous generator and proposal of problem solutions by the introduction of a decoupled generation system with additional degree of freedom. Computer calculations are used as design and for preliminary verification. Tests in a real laboratory system equipped with modern components such as electrical machines and power electronic converters proved the theory.

Decoupled generation is realized in a very original way using new blocks, integration method and control. The developed system has been awarded more than six world patents. The system has additional degrees of freedom in speed and grid connection operation.

The research team has concentrated its research over many years and developed a generation system which has been awarded a great number of patents. A special axial flux, light and simple permanent magnet generator was developed and integrated to the prime mover. A three‐phase AC/AC power electronic converter and a DSP controller are integrated to a very small size and low weight. The invented topology provides a very reliable operation, high‐quality AC voltage in fully three‐phase non‐symmetrical load. There were also presentations on world conferences (EPE, PESC, EPE‐PEMC).

Wind energy has matured to a level of development at which it is ready to become a generally accepted power generation technology. The aim of this paper is to provide a brief review of the state of the art in the area of electrical machines and power‐electronic systems for high‐power wind energy generation applications. As the first part of this paper, latest market penetration, current technology and advanced electrical machines are addressed.

After a short description of the latest market penetration of wind turbines with various topologies globally by the end of 2010 is provided, current wind power technology, including a variety of fixed‐ and variable‐speed (in particular with doubly‐fed induction generator (DFIG) and permanent magnet synchronous generator (PMSG) supplied with partial‐ and full‐power converters, respectively) wind power generation systems, and modern grid codes, is presented. Finally, four advanced electrical‐machine systems, viz., brushless DFIG, open winding PMSG, dual/multi 3‐phase stator‐winding PMSG and magnetic‐gear outer‐rotor PMSG, are identified with their respective merits and challenges for future high‐power wind energy applications.

For the time being, the gear‐drive DFIG‐based wind turbine is significantly dominating the markets despite its defect caused by mechanical gears, slip rings and brush sets. Meanwhile, direct‐drive synchronous generator, especially utilizing permanent magnets on its rotor, supplied with a full‐capacity power converter has become a more effective solution, particularly in high‐power offshore wind farm applications.

This first part of the paper reviews the latest market penetration of wind turbines with a variety of mature topologies, by summarizing their advantages and disadvantages. Four advanced electrical‐machine systems are selected and identified by distinguishing their respective merits and challenges for future high‐power wind energy applications.

Doubly fed induction generator DFIG applied in over 50 percent of modern variable speed wind power systems and interesting also for adjustable speed diesel generation sets or multi‐megawatt water turbines is troublesome in the mean of maintenance of slip‐rings and brushes. Especially, it concerns isolated power systems and offshore wind turbines. Application of brushless DFIG in such cases eliminates the mentioned problem. Constructions of the machine and consequently the model and mathematical description is more complicated than classical slip‐ring DFIG, therefore it is still developed in several scientific institutions to obtain adequate performance. The following work is dedicated to mathematical description, modelling and implementation of the control method for autonomous operation in the laboratory model of brushless DFIG.

Analysis and simulation of the machine model and laboratory tests on a small scale prototype of brushless DFIG.

It has been proven that sensorless direct voltage control of DFIG can be applied for both slip‐ring and brushless machines, as it does not require machine parameters.

Brushless DFIG development is far from the performance needed by industrial implementation. Lower efficiency and higher reactive power needed by the machine, in comparison to classical DFIG of the same power range, result from double air gap seen by magnetic flux. However, the constructions of prototype machines are better and better, and their capabilities become closer to DFIG.

Variable and adjustable speed generation systems such as wind turbines, diesel generation sets, water turbines.

Standalone power systems with DFIG described in several papers require quite complicated control methods based on the mathematical equations of the machine model. Thus, these methods have to be significantly modified for the brushless version of this machine type, due to the fact of a much more complicated model. The proposed sensorless method of the output voltage control requires only redesign (tuning) of the PI controllers responsible for control of the rotor current, stator voltage amplitude and frequency.

Doubly fed induction generator (DFIG) is widely used in wind energy conversion systems and it can operate with other primary movers. The purpose of this paper is to focus on the standalone operation of DFIG which may expand the area of possible applications and increase capabilities of the generation system in terms of power quality.

Synthesis of the control method was preceded by analysis of mathematical model of the machine. The control method based on the negative sequence and high harmonics extraction has been developed and verified in the laboratory unit. Control of the fundamental frequency component uses neither rotor speed nor position sensors.

The original method allows to compensate negative sequence and high harmonics of the generated voltage. At the same time, due to the active filtering capability of the grid side converter, the stator phase current shape is close to sine wave. Thus, it is seen by the machine as a linear load, what eliminates the electromagnetic torque ripples.

The system and control method can be applied in variable speed generation systems, e.g. wind turbines or diesel engines operating in the standalone mode.

Although the selective compensation of negative sequence and harmonics are known in the literature, until now the methods have been verified for the system with a rotor position sensor. Moreover, the stator current feed-forward improving the transient properties, as well as results of transient states caused by the load step change, have not been proposed in publications.

This paper aims to provide a permanent magnet synchronous generator (PMSG) wind turbine, which feeds electric power (AC) to the power grid. The converter, located on the machine side, is used to produce the full amount of wind power. Research on wind energy conversion system (WECS) is carried out in this study using a direct wind turbine in MATLAB with constant and variable speeds.

This paper is about WECS using PMSG and is connected to a grid of two serial converters with common DC connections.

This paper aims to provide the value of DC connection voltage at its base, regardless of the wind speed alterations, the inverter's output ac voltage can be kept constant.

This paper aims to provide a Hill Climb Search maximum power point tracking (MPPT) algorithm is an effective control system for extracting maximum energy, also called voltage control, pitch control, phase-locked loop (PLL) controls, from a wind turbine. Using the Fuzzy controller, the grid side converter is controlled.

The purpose of this paper is to consider both sides of a back‐to‐back AC‐DC‐AC interface.

The paper presents a mathematical analysis, simulation, laboratory test in scaled model.

The two main findings comprised concept of control methods for grid AC‐DC‐AC converter applied in renewable energy sources with variable speed operation under distorted grid. Active filtering functionality in case of non‐linear current of a parallel load. Second, a control algorithm dedicated for two‐level AC‐DC converter applied in industrial networks with high‐order harmonics compensation working under hard conditions – balanced and unbalanced voltage dips.

The paper shows preliminary results for AC‐DC‐AC converter and active filter (AF) during voltage dips and for harmonics compensation. Control methods and/or topology should be improved and tested in scale and after at high‐power system.

Power quality supplied/received to/from the grid can be increased. In case of low‐cost system only AF can be applied to existing non‐linear receivers. Moreover, in case of full AC‐DC‐AC converter energy saving and production is possible.

Presented control methods give satisfactory results. Paper presents laboratory results for grid and machine side two different power circuits during steady states and transients. Moreover, active filtering operation during voltage dips is presented.

This article seeks to present the simple and easy to manufacture design of a permanent magnet generator based on coreless windings. An example is shown of basic calculations based on an equivalent magnetic circuit. Finally, a description of a 20 kW prototype of PMSG is presented based on rectangular magnets which contains mechanical design and experimental results.

The analysis presents flux dependence using several parameters such as: magnet's grade and size in comparison with coil and air‐gap dimensions. The second part of the article concentrates on simulation results of Finite Element Method analysis (FEM) that clearly shows the flux distribution for different magnet shapes – trapezoidal and rectangular.

The presented topology of the machine has several advantages, e.g. there is no starting and cogging torque which is very important especially for wind power systems because of the start up point of the turbine. Moreover, it is cheap and easy to manufacture because of ironless technology in stator. The generator can be produced in the range of single watts up to hundreds of kilo watts of power in multi disk operation.

The ironless technology applied to the stator, results in the need for using stronger magnets in comparison with a classic iron‐core permanent magnet machine.

This axial‐flux machine seems to be very interesting for low speed power generation systems such as wind and water turbines. Cost effective permanent magnet generator can be used for local power generation (e.g. heating). The generator can also be connected to the main grid through a special grid‐tie‐inverter.

The article presents the simple and rarely presented topology and describes a few methods of optimisation of the parameters to achieve maximum power.

This paper aims to deal with the problem of the global stabilization for a class of tension leg platform (TLP) nonlinear control systems.

It is well-known that, in general, the global asymptotic stability of the TLP subsystems does not imply the global asymptotic stability of the composite closed-loop system.

An effective approach is proposed to control chaos via the combination of fuzzy controllers, fuzzy observers and dithers.

If a fuzzy controller and a fuzzy observer cannot stabilize the chaotic system, a dither, as an auxiliary of the controller and the observer, is simultaneously introduced to asymptotically stabilize the chaotic system.

Thus, the behavior of the closed-loop dithered chaotic system can be rigorously predicted by establishing that of the closed-loop fuzzy relaxed system.

The purpose of this study is to develop a theoretical model for examining how innovation speed mediates the relationship between knowledge management (KM) and performance and empirically tests the proposed model using data collected in the USA and China over three years.

To avoid common method bias and increase ability to draw causal effects of KM on performance, data were collected over three years. KM data were collected by survey; innovation speed data were collected in the following year; and sales growth and gross margin data were collected over the next three years. After merging the three data sets, the final empirical data used for this study contained data from 354 USA and 647 Chinese firms. Multiple regression analyses were used to test the research hypotheses. Sobel mediation tests were performed to test the mediating effects of innovation speed on the relationship between KM and performance.

Innovation speed has a U-shaped relationship with performance in both US and Chinese firms. Knowledge generation has an inverted U-shaped relationship with innovation speed in both US and Chinese firms. Knowledge dissemination increases innovation speed in US firms but not in Chinese firms. While knowledge application increases innovation speed in the US firms, it decreases innovation speed in Chinese firms.

This study is among the first to propose and empirically test the KM-innovation speed-performance relationship. This paper advances the KM literature by demonstrating that there is an inverted U-shaped relationship between knowledge generation and innovation speed and that there is a U-shaped relationship between innovation speed and performance. In addition, this study contributed to the cross-national study of KM.

It has been argued that innovation speed has been inappropriately absent in models of market orientation. The present study seeks to provide new insights into whether and how market orientation's three main components: intelligence generation, intelligence dissemination, and responsiveness affect innovation speed and new product performance, and about the mediating role of innovation speed.

Data were collected from a sample of 247 firms in a variety of manufacturing industries. A mail survey was developed to collect the data.

The results indicate that intelligence generation has an indirect positive effect on innovation speed via intelligence dissemination and responsiveness. Intelligence dissemination influences innovation speed positively, both directly and indirectly through responsiveness. Findings report a curvilinear (J‐shaped) relationship between responsiveness and innovation speed. With regard to the effect of the market orientation's components on new product performance, the findings indicate a positive relationship between responsiveness and new product performance. The parameter estimates for the direct paths linking intelligence generation and intelligence dissemination with new product performance were found to be not significant. Instead, the findings show that intelligence generation and intelligence dissemination influence new product performance indirectly through responsiveness. Finally, a positive relationship was found between innovation speed and new product performance.

The research makes three important contributions to the marketing strategy and new product development literatures. First, by splitting market orientation into the components of intelligence generation, intelligence dissemination and responsiveness, the study provides a closer examination into the effect of market orientation on innovation speed and new product performance. Second, the results indicate that the effects of intelligence generation and intelligence dissemination on innovation speed and new product performance are mediated by responsiveness to market intelligence. Third, findings support the argument that innovation speed partially mediates the effect of market orientation's three main components on new product performance.