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Delegates are invited to meet and discuss with the poster presenters during the poster presentation sessions between 10:30-11:30 and 16:00-17:00 on Thursday, 19 November 2015.

Lead Session Chair:
Stephan Barth, ForWind - Center for Wind Energy Research, Germany
vanya ignatova Schneider Electric, France
Co-authors:
Vanya Ignatova (1) F Christophe Littaye (1) Sylvain Ratel (1)
(1) Schneider Electric, Eybens, France

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Presenter's biography

Biographies are supplied directly by presenters at EWEA 2015 and are published here unedited

Vanya Ignatova is currently an Electrical architect for co-generation and renewables at Schneider Electric. Vanya received her PhD from Institut National Polytechnique de Grenoble. She joined Schneider Electric in 2006 as an Electrical Engineering Expert for low voltage electrical installations sizing and calculation, then as Offer Creation Manager for energy management and power quality offers, dedicated to the Industrial segments. Since 2015, Vanya is in charge of the electrical reference design for projects integrating gensets and renewable energies


Poster

Poster Download poster (7.39 MB)

Abstract

Overview on power quality issues when connecting wind turbines to the grid

Introduction

In the last years the use of renewable energies (Wind turbines, solar farms and others) has drastically increased. Those new generation systems have specific power quality characteristics that should be considered when integrating them to the grid.

Approach

The purpose of this paper is to provide an overview of the power quality problems coming up when connecting wind turbines to the grid, the standards requirements and guidelines, as well as the available solutions to improve the power quality and network reliability. Reference design examples for wind turbines generator systems integration into the grid are provided at the end of this paper.

Main body of abstract

In an ideal three phase power system, voltages are at nominal magnitude and frequency, perfectly balanced and with a perfect sinusoidal waveform. Any disturbance on one parameter (magnitude, frequency, waveform, or symmetry) is classified as a power quality problem. There are a variety of power quality disturbances – voltage dips, harmonics, transients, etc. – all of which can have negative impacts on the electrical system and equipment, such as power outage, device damage, failure, overheating, degraded performance and reduced equipment life.

Grid connected wind turbines do affect the power quality. They are highly variable sources of energy and may lead to power quality issues, such as voltage sags, transients, harmonics, voltage variations and flicker.

The voltage variations are the most common power quality issue linked to the use of renewable energy. All kind of turbines cause voltage variations. They are usually generated during the normal wind turbines operation, but can be also caused during switching operations.

Voltage dips are another frequent issue coming up from wind turbines starting and switching operations. However the voltage dips generated by wind turbines are usually characterized by low magnitude and to not affect the grid reliability.

Harmonics can be also generated, specifically from variable speed wind turbines, equipped with power quality equipment.

Frequency variations and flicker are common issues as well, coming up from both speed-fixe and variable speed wind turbines.

The final paper presents an overview of these and other disturbances in regards with the wind turbines, provides the limits recommended by standards and explains the potential poor power quality impact on the grid and the connected equipment.

On the other side, wind turbines operation can be affected by the poor power quality of the grid. This is specifically the case when wind turbines are connected to weak grids. Those are characterized by large voltage and frequency variation that can lead to wind turbines generation system malfunction and under performance

Different type of equipment can be used to improve the power quality and stabilize the delivered power. Main solutions include STATCOM, reactive power compensation, active filters and power quality conditioning system. These solutions are analyzed and compared in the final version of this paper.

Also common electrical designs for the connection of wind farms to the grid are provided at the end of this paper.


Conclusion

The paper explains in a simple way and with concrete examples the power quality issues that are facing today the wind turbines generation systems. It gives recommendation for power quality mitigation solutions and grid integration guidelines and reference design.


Learning objectives
This paper relates on one of the main challenges regarding the integration of wind energy into the power systems - the interaction between the grid and the wind turbines, the quality of the delivered power and the impact on wind turbines generation systems of poor grid power quality.