EPE Journal Volume 18-3 
 You are here: EPE Documents > 02 - EPE Journal Papers > EPE Journal Volume 18-3 
EPE Journal Volume 18-3 - Editorial
EPE Journal Volume 18-3 - Papers
EPE Journal Volume 18-3 - Seminars



 EPE Journal Volume 18-3 - Editorial 

Wind Turbines will Provide the Energy Needed in the Future, and Create a Lot of Jobs  [Details]
By T. Undeland

Papers in this Journal were selected from the first EPE Seminar on Wind Energy that took place in Delft on 27 and 28 March this year… Enjoy the reading. Now the call for papers for the 2nd EPE Wind Energy Chapter Seminar in Stockholm on 23 and 24 April 2009 is out, deadline for the synopsis is 14 November 2008.


 EPE Journal Volume 18-3 - Papers 

Promising Direct-Drive Generator System for Large Wind Turbines  [Details]
By Deok-je Bang; Henk Polinder; Ghanshyam Shrestha; Jan Abraham Ferreira

The aim of this paper is to review direct-drive generators and to propose promising direct-drive generator concepts for large wind turbines. Different large direct-drive generators are compared based on the mass and the torque rating. Features of different PM machines are investigated to find a suitable machine type for direct-drive. Some promising solutions are proposed for both electromagnetic and mechanical design.

Experiment of a Wind Generator Participation to Frequency Control  [Details]
By Vincent Courtecuisse, Jonathan Sprooten, Benoît Robyns, Jacques Deuse

This paper presents a hardware implementation of the participation of a wind turbine to network primary frequency control. The increase of renewable production of electricity requires the participation of these generators to ancillary services. The proposed method, by actions on the pitch angle and the generator torque through fuzzy logic controllers, creates a power reserve. This reserve is regular on a large range of wind speeds and is constituted without any wind speed measurement. Furthermore, the proposed strategy uses this reserve in case of frequency deviation to provide additional active power to stabilise the electrical grid. The implementation of such strategy on a 2.2 kW test bench representing a wind turbine and its generator validates the practical feasibility of the method. Finally, the regularity of the reserve is shown to be weakly dependant on the dynamics of the wind turbine controls.

Loss and Rating Considerations of a Wind Energy Conversion System with Reactive Compensation by Magnetic Energy Recovery Switch (MERS)  [Details]
By Jan Arild Wiik; Arkadiusz Kulka; Takanori Isobe; Kazuhiro Usuki; Marta Molinas; Taku Takaku; Tore Undeland; Ryuichi Shimada

Electrical conversion system for permanent magnet wind generators is challenging due to the large rating of power semiconductor devices needed and the associated costs and losses. This motivates the search for new configurations improving these relationships. Additionally, due to the large inductance present in the generator (synchronous reactance), voltage drops results with resistive load and the generator output power is limited. Traditionally, a conventional active rectifier is used, with a 3-level type illustrated in Fig. 1a. The main challenges with this solution are the costs and also increased losses resulting from high speed switching and filter operation.
A solution utilizing an active series compensation device combined with a diode bridge is investigated in this paper as shown in Fig. 1b. The series compensator supplies only reactive power with a resulting good generator utilization. This also means that the VA capability of the active semiconductor part can be reduced compared to an active rectifier since the active rectifier also needs to supply the full active power.
The use of an active series compensator called Magnetic Energy Recovery Switch (MERS) is studied. MERS is a simple configuration with low switching losses and simple control acting as a variable capacitor. Due to the special characteristics of this configuration, a new IGBT with low on-state voltage has been developed. The performance of the configuration has been confirmed with experiments on a 50 kW multi-pole permanent magnet generator. Numerical investigations on large scale system indicate potential for loss reductions and power semiconductor rating reduction compared to using an active rectifier solution.

Resonance in the 132 MW Wind Farm With Long High Voltage Cable and its Compensation  [Details]
By Juriy Plotkin; Uwe Schaefer; Rolf Hanitsch

The origin for the low power quality at the output of a 132 MW wind farm has been investigated. A resonant circuit formed by the wind farm components is found to be responsible for a high level of the 7th current harmonic. The structure of the investigated wind farm is similar to those of offshore wind farms with AC cable connection. The same resonance problem is expected to occur in offshore installations with long high voltage AC cables. Various compensation strategies are proposed and analyzed.

Energy Storage, a Condition for Integrating Natural Energy Sources into the Electrical Grid  [Details]
By Werner Leonhard

Sustainability by using regenerative sources is a longterm political goal, the reasons are the finite fossil resources and the avoidance of emissions and waste. Of the natural energy sources, wind is considered in Europe to offer best promise for contributing in the coming decades a substantial portion of the electrical supply. It is discussed, how the environmentoriented policy in Germany of feeding with priority large quantities of privileged wind power into the supply affects the stability of the grid and whether it can relieve the dependence on fossil and nuclear fuels. Generation of storable secondary energy carriers such as hydrogen for decoupling the fluctuating supply and demand may be a preferable alternative. The possibility of processing the CO2-emissions of coal power stations with regenerative hydrogen, similar to natural photosynthesis, is briefly discussed.


 EPE Journal Volume 18-3 - Seminars 

2nd EPE Wind Energy Chapter Seminar - Call for Papers  [Details]
By B. Sneyers

As wind has become the most technically and commercially advanced as well as most promising source of renewable energy, the European Power Electronics and Adjustable Speed Drives Association (EPE) dedicated a special chapter on this issue: the EPE Wind Energy Chapter. After the successful gathering at the 1st EPE Wind Energy Chapter Seminar held in Delft on 27 and 28 March 2008, it has been decided to organize a second EPE Wind Energy Chapter seminar where experts can discuss various electrotechnical aspects related to the development of wind energy. This seminar will take place on 23 and 24 April 2009 in Stockholm, Sweden. The aim is to meet, discuss and get acquainted with the latest development of this fast developing technology, in an informal and friendly atmosphere.

8th International Symposium on Advanced Electromechanical Motion Systems - Call for Papers  [Details]
By B. Robyns

ELECTROMOTION 2009, the 8th International Symposium on Advanced Electromechanical Motion Systems, and the EPE Chapter “Electric Drives”, will take place on 1- 3 July 2009 in Lille, France, on the HEI Graduate School site created in 1885 in the centre of the City. It is organized jointly by L2EP, Laboratory of Electrotechnics and Power Electronics

ELECTROMOTION Symposium is a major biennial event bringing together scientists, engineers, manufacturers and users from all over the world in order to provide an exchange of information and creative ideas concerning recent developments and future trends in analysis, design and applications of:
- Electromechanical energy converters
- Advanced electric motors
- Electric vehicles and traction drives
- Electromechanical actuators
- Electromechatronic components and systems
- Electric transducers for mechanical quantities
- Renewable sources of energy and cogeneration
- Electric power systems