The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Arne Hejde Nielsen - One of the best experts on this subject based on the ideXlab platform.
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modelling and transient stability of large wind farms
International Journal of Electrical Power & Energy Systems, 2003Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde Nielsen, Jorgen Kaas Pedersen, Niels Kjolstad PoulsenAbstract:The paper is dealing with modelling and short-term voltage stability considerations of large wind farms. A physical model of a large offshore wind farm consisting of a large number of Windmills is implemented in the dynamic simulation tool PSS/E. Each windmill in the wind farm is represented by a physical model of grid-connected Windmills. The windmill generators are conventional induction generators and the wind farm is ac-connected to the power system. Improvements of short-term voltage stability in case of failure events in the external power system are treated with use of conventional generator technology. This subject is treated as a parameter study with respect to the windmill electrical and mechanical parameters and with use of control strategies within the conventional generator technology. Stability improvements on the wind farm side of the connection point lead to significant reduction of dynamic reactive compensation demands. In case of blade angle control applied at failure events, dynamic reactive compensation is not necessary for maintaining the voltage stability.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
Vladislav Akhmatov - One of the best experts on this subject based on the ideXlab platform.
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modelling and transient stability of large wind farms
International Journal of Electrical Power & Energy Systems, 2003Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde Nielsen, Jorgen Kaas Pedersen, Niels Kjolstad PoulsenAbstract:The paper is dealing with modelling and short-term voltage stability considerations of large wind farms. A physical model of a large offshore wind farm consisting of a large number of Windmills is implemented in the dynamic simulation tool PSS/E. Each windmill in the wind farm is represented by a physical model of grid-connected Windmills. The windmill generators are conventional induction generators and the wind farm is ac-connected to the power system. Improvements of short-term voltage stability in case of failure events in the external power system are treated with use of conventional generator technology. This subject is treated as a parameter study with respect to the windmill electrical and mechanical parameters and with use of control strategies within the conventional generator technology. Stability improvements on the wind farm side of the connection point lead to significant reduction of dynamic reactive compensation demands. In case of blade angle control applied at failure events, dynamic reactive compensation is not necessary for maintaining the voltage stability.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
Hans Knudsen - One of the best experts on this subject based on the ideXlab platform.
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modelling and transient stability of large wind farms
International Journal of Electrical Power & Energy Systems, 2003Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde Nielsen, Jorgen Kaas Pedersen, Niels Kjolstad PoulsenAbstract:The paper is dealing with modelling and short-term voltage stability considerations of large wind farms. A physical model of a large offshore wind farm consisting of a large number of Windmills is implemented in the dynamic simulation tool PSS/E. Each windmill in the wind farm is represented by a physical model of grid-connected Windmills. The windmill generators are conventional induction generators and the wind farm is ac-connected to the power system. Improvements of short-term voltage stability in case of failure events in the external power system are treated with use of conventional generator technology. This subject is treated as a parameter study with respect to the windmill electrical and mechanical parameters and with use of control strategies within the conventional generator technology. Stability improvements on the wind farm side of the connection point lead to significant reduction of dynamic reactive compensation demands. In case of blade angle control applied at failure events, dynamic reactive compensation is not necessary for maintaining the voltage stability.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
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advanced simulation of Windmills in the electric power supply
International Journal of Electrical Power & Energy Systems, 2000Co-Authors: Vladislav Akhmatov, Hans Knudsen, Arne Hejde NielsenAbstract:An advanced model of a grid-connected windmill is set up where the windmill is a complex electro-mechanical system. The windmill model is implemented as a standardised component in the dynamic simulation tool, PSS/E, which makes it possible to investigate dynamic behaviour of grid-connected Windmills as a part of realistic electrical grid models. This means an arbitrary number of wind farms or single Windmills within an arbitrary network configuration. The windmill model may be applied to the study of electric power system stability and of power quality as well. It is found that a grid-connected windmill operates as a low-pass filter, whereby the two following observations are made: (1) interaction between the electrical grid and the mechanical systems of grid-connected Windmills is given by a low frequency oscillation as the result of disturbances in the electric grid; (2) flicker, which is commonly explained by the dynamic wind variation, may also be caused by mechanical eigenswings in the windmill mechanical construction.
Dieter Nagel - One of the best experts on this subject based on the ideXlab platform.
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SDF - MPRF waveform for ground based radars to suppress returns from Windmills and rain clutter
2015 Sensor Data Fusion: Trends Solutions Applications (SDF), 2015Co-Authors: Dieter NagelAbstract:Renewable energy sources such as wind parks are more and more shaping our environment. In the vicinity of radars, however, they often pose a serious problem, due to degradation of radar performance [6]. This paper deals with a new MPRF waveform capable of suppressing returns from wind parks and strong rain clutter and thus mitigating this performance degradation. Most ground based radars use low PRF (LPRF) waveforms with pulse repetition frequencies (PRF) below ~1000Hz, allowing unambiguous range measurements out to more than 150km. The advantage of this waveform for ground based radars is that, assuming a duty ratio of approx. 10%, the near-in ground clutter less than 15km from the radar falls into the eclipsed transmit blind zones. A further advantage is the large unambiguous range measurement interval and the possibility of using Sensitivity-Time Control (STC) [1] to suppress low radar cross section returns. A disadvantage of LPRF is the small unambiguous Doppler velocity interval which, e.g., for S-band radars, is less than ~50m/s. In the case of windmill farms, it is possible that, due to the maximum velocity of the rotor tips of ~50m/s the whole Doppler velocity region for the affected range intervals is occupied by rotor blade returns. Also, in the case of heavy rain, the whole Doppler region over a range interval of several miles could be occupied by rain clutter. This paper presents a MPRF waveform which can mitigate the effects of Windmills and rain clutter on the detectability of true targets.
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MPRF waveform for ground based radars to suppress returns from Windmills and rain clutter
2015 Sensor Data Fusion: Trends Solutions Applications (SDF), 2015Co-Authors: Dieter NagelAbstract:Renewable energy sources such as wind parks are more and more shaping our environment. In the vicinity of radars, however, they often pose a serious problem, due to degradation of radar performance. This paper deals with a new MPRF waveform capable of suppressing returns from wind parks and strong rain clutter and thus mitigating this performance degradation. Most ground based radars use low PRF (LPRF) waveforms with pulse repetition frequencies (PRF) below ~1000Hz, allowing unambiguous range measurements out to more than 150km. The advantage of this waveform for ground based radars is that, assuming a duty ratio of approx. 10%, the near-in ground clutter less than 15km from the radar falls into the eclipsed transmit blind zones. A further advantage is the large unambiguous range measurement interval and the possibility of using Sensitivity-Time Control (STC) to suppress low radar cross section returns. A disadvantage of LPRF is the small unambiguous Doppler velocity interval which, e.g., for S-band radars, is less than ~50m/s. In the case of windmill farms, it is possible that, due to the maximum velocity of the rotor tips of ~50m/s the whole Doppler velocity region for the affected range intervals is occupied by rotor blade returns. Also, in the case of heavy rain, the whole Doppler region over a range interval of several miles could be occupied by rain clutter. This paper presents a MPRF waveform which can mitigate the effects of Windmills and rain clutter on the detectability of true targets.
I. Safari - One of the best experts on this subject based on the ideXlab platform.
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The effect of the windmill's parameters on the capacity factor
IEEE Transactions on Energy Conversion, 1995Co-Authors: Z.m. Salameh, I. SafariAbstract:In this paper a methodology to study the effect of the windmill's parameters on the capacity factor is presented. The study is based on finding the capacity factors (CF) of the identically rated available Windmills. This is done by using long term wind speed data recorded at different hours of the day for many years. This data is then used to generate mean wind speeds for a typical day in a month. Probability density functions for the mean wind speeds for the different hours of the day are generated and used to calculate the capacity factors for the Windmills taking into account the manufacturer's parameters of the Windmills. The study shows that although the Windmills have the same rating they have different capacity factors. The windmill with the highest average capacity factor for the specific site is to be recommended.
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Optimum windmill-site matching
IEEE Transactions on Energy Conversion, 1992Co-Authors: Z.m. Salameh, I. SafariAbstract:A methodology for the selection of the optimum windmill for a specific site is developed. The selection is based on finding the capacity factors of the available Windmills. This is done by using long-term wind speed data recorded at different hours of the day for many years. These data are then used to generate mean wind speeds for a typical day in a month. Probability density functions for the mean wind speeds for the different hours of the day are generated with the manufacturer's specifications on the Windmills used to calculate the capacity factors for the Windmills. The windmill with the highest average capacity factor for the specific site is the optimum one and should be recommended. >
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Optimum windmill - Site matching. Discussion
1992Co-Authors: Z.m. Salameh, I. Safari, SöderAbstract:In this paper a methodology for the selection of the optimum windmill for a specific site is developed. The selection is based on finding the capacity factors (CF) of the available Windmills. This is done by using long term wind speed data recorded at different hours of the day for many years. This data is then used to generate mean wind speeds for a typical day in a month. Probability density functions for the mean wind speeds for the different hours of the day are generated with the manufacturer's specifications on Windmills used to calculate the capacity factors for the Windmills
