Troels Sørensen

Validation of the Standard Method for Assessing Flicker From Wind Turbines

This paper studies the validity of the standard method in IEC 61400-21 for assessing the flicker emission from multiple wind turbines. The standard method is based on testing a single wind turbine and then using the results of this test to assess the flicker emission from a number of wind turbines. This study is based on the data from two wind farms, one with fixed-speed wind turbines and one with variable-speed wind turbines. The data are: a type test at the terminals of a wind turbine, and measurements at the connection of a collection line to the substation. The type test data are used to assess the flicker emission at the collection line; this assessment is then compared to the actual measurements in order to study the accuracy of the estimation. It was observed in both wind farms, that the assessment based on the standard method is statistically conservative compared to the measurements. The reason for this is the statistical characteristics of flicker emission.

Power Quality Issues on Wind Power Installations in Denmark

This paper introduces the power quality issues of wind power installations in a historic perspective, as the development from a few small wind turbines connected directly to the low voltage grid, to the present system with high penetration on the medium voltage distribution grids and two large offshore wind farms connected at transmission level. In this perspective, the power quality issues are divided into local issues particularly related to the voltage quality in the distribution systems and global issues related to the power system control and stability. Power quality characteristics of wind turbines and wind farms are described according to national and international standards, and measurements from wind farms are presented.

Harmonic modelling, propagation and mitigation for large wind power plants connected via long HVAC cables: Review and outlook of current research

This paper presents a state-of-the-art review on grid connection of large offshore wind power plants (OWPPs) using extra-long high voltage AC (HVAC) cables. The paper describes research by DONG Energy Wind Power in close collaboration with Aalborg University addressing related challenges through an industrial PhD project. The overall goal is to gain a better understanding of extra-long HVAC cable connected OWPPs, in order to ensure reliability and availability of OWPPs. This will reduce the cost of energy, as the risk of costly delays and modifications after the project has been commissioned can be reduced and operational availability and the reliability can be improved. Challenges hereto include lower resonance frequencies due to the long cables, frequency dependent modelling of long submarine cables, passive filtering, and PLL dynamics in the control loops (from a harmonic stability point of view).

Challenges with harmonic compensation at a remote bus in offshore wind power plant

This paper investigates the challenges associated with remote harmonic compensation in offshore wind power plants through long cables and transformers. The interaction between the grid network and the wind power plant network can lead to the amplification of certain harmonics and potentially resonant conditions. Hence, the plant developer is required to maintain the harmonic distortion at the point of common coupling within the planning level limits using harmonic compensation, which is usually done by static filters. In this paper an active damping compensation strategy with a STATCOM using emulation of using emulation of resistance at the harmonic frequencies of concern is analyzed. Finally the results are demonstrated using time domain simulations in PSCAD.

Proceedings of 2016 IEEE International Conference on Environment and Electrical Engineering (EEEIC 2016)

This paper investigates the challenges associated with remote harmonic compensation in offshore wind power plants through long cables and transformers. The interaction between the grid network and the wind power plant network can lead to the amplification of certain harmonics and potentially resonant conditions. Hence, the plant developer is required to maintain the harmonic distortion at the point of common coupling within the planning level limits using harmonic compensation, which is usually done by static filters. In this paper an active damping compensation strategy with a STATCOM using emulation of using emulation of resistance at the harmonic frequencies of concern is analyzed. Finally the results are demonstrated using time domain simulations in PSCAD.

Proceedings of EEEIC 2016 - International Conference on Environment and Electrical Engineering

This paper investigates the challenges associated with remote harmonic compensation in offshore wind power plants through long cables and transformers. The interaction between the grid network and the wind power plant network can lead to the amplification of certain harmonics and potentially resonant conditions. Hence, the plant developer is required to maintain the harmonic distortion at the point of common coupling within the planning level limits using harmonic compensation, which is usually done by static filters. In this paper an active damping compensation strategy with a STATCOM using emulation of using emulation of resistance at the harmonic frequencies of concern is analyzed. Finally the results are demonstrated using time domain simulations in PSCAD.