Control strategy for constant-speed wind turbine in below rated wind speed

The objective of this thesis is to design a control strategy to improve power capture in below rated wind speed for constant speed pitch regulated wind turbines.To achieve the objective of this thesis, it is convenient to model rotor/wind-field interaction by a simple ordinary differential equation. It is also required to use a simple model to represent the dynamic behaviour of a grid connected constant speed horizontal axis wind turbine to assess the performance of the proposed control strategy. Simulink based simulations of the wind model and turbine dynamics combined with the control strategy is performed to analyse its performance and to estimate the extra power capture by using the control system in below rated wind speed in comparison to running the turbine with fixed blade pitch angle (without the use of control strategy) in the same region.The objective of this thesis is to design a control strategy to improve power capture in below rated wind speed for constant speed pitch regulated wind turbines.To achieve the objective of this thesis, it is convenient to model rotor/wind-field interaction by a simple ordinary differential equation. It is also required to use a simple model to represent the dynamic behaviour of a grid connected constant speed horizontal axis wind turbine to assess the performance of the proposed control strategy. Simulink based simulations of the wind model and turbine dynamics combined with the control strategy is performed to analyse its performance and to estimate the extra power capture by using the control system in below rated wind speed in comparison to running the turbine with fixed blade pitch angle (without the use of control strategy) in the same region

Control strategy for variable-speed wind turbine in below rated wind speed

Generating electrical power from renewable sources has increased substantially over the past decades and one of the most capable is wind power. From this energy source, the electrical power is directly generated using wind turbines. The type of the wind turbine used for this project is a variable-speed horizontal-axis wind turbine. Comparing variable speed wind turbines with constant speed wind turbines, variable speed machines have several advantages over constant speed machines, which outweigh the substantial cost of the power electronics necessary to obtain variable speed operations.;The major advantage in below rated wind speed is additional energy capture and in above rated wind speed the frequent mentioned advantage is additional power-train compliance and associated load alleviation.;In variable speed wind turbines, the operational strategy is regularly selected to maximise the energy capture. For this purpose, the operating state of the wind turbine is caused to track the Cpmax curve, which is the maximum aerodynamic efficiency curve. The accuracy of this tracking depends on the controller designed for the wind turbine and the control strategy used. The purpose of this project is to investigate a control strategy for a variable-speed wind turbine in below rated wind speed to improve the power capture. To achieve the objective of this thesis, a controller to track the Cpmax curve is designed in this project.;The controller is validated using a Simulink model developed to the wind turbine. The Simulink model tested for different wind speeds from 4 m/s to 12 m/s with different turbulences from 5% to 20%.Generating electrical power from renewable sources has increased substantially over the past decades and one of the most capable is wind power. From this energy source, the electrical power is directly generated using wind turbines. The type of the wind turbine used for this project is a variable-speed horizontal-axis wind turbine. Comparing variable speed wind turbines with constant speed wind turbines, variable speed machines have several advantages over constant speed machines, which outweigh the substantial cost of the power electronics necessary to obtain variable speed operations.;The major advantage in below rated wind speed is additional energy capture and in above rated wind speed the frequent mentioned advantage is additional power-train compliance and associated load alleviation.;In variable speed wind turbines, the operational strategy is regularly selected to maximise the energy capture. For this purpose, the operating state of the wind turbine is caused to track the Cpmax curve, which is the maximum aerodynamic efficiency curve. The accuracy of this tracking depends on the controller designed for the wind turbine and the control strategy used. The purpose of this project is to investigate a control strategy for a variable-speed wind turbine in below rated wind speed to improve the power capture. To achieve the objective of this thesis, a controller to track the Cpmax curve is designed in this project.;The controller is validated using a Simulink model developed to the wind turbine. The Simulink model tested for different wind speeds from 4 m/s to 12 m/s with different turbulences from 5% to 20%

Iranian Professors’ Attitude toward the Iran-US Relationships in 1408 (2029)

The present research was performed to evaluate the Iran-US relationships in 2029 from the Iranian Professors’ point of view. Investigations were perfumed via future studies in two parts: The first part is based on library studies, and the second part is questionnaire-based field surveys, with the acquired data analyzed using MicMac and Scenario Wizard software tools. Based on the results of the analysis in the MicMac software, a total of 20 driver forces for the Iran-US relationships were identified. Considering the driver forces as descriptors of the Iran-US relationships, the most significant driver forces were found to be the government institutions context followed by the relationship-interfering countries, the role of the two countries’ leaders, future of the international system, think tanks, lobbies and pressure groups, nuclear capabilities and missile program of Iran, the role of geography, and historical records of the relationships between the two countries. Based on the outputs of the Scenario Wizard software, five scenarios were identified, including highly favorable, favorable, moderate, unfavorable, and highly unfavorable, with the development of the Iran-US relationships under the moderate scenario being highly probable

Reconstruction of Missing Daily Streamflow Data using the MissForest Algorithm in Southern Baluchestan Basin, Iran

Extended Abstract Background: Long-term hydrometeorological variables can be used for planning and managing water resources at the basin level using different physical models, such as hydrological and hydraulic models. However, such variables are often accompanied by missing data, which makes analysis difficult or sometimes impossible. Data gaps cause problems in interpretation, model calibration, and biased statistics. In this study, the validity of a non-parametric random learning machine algorithm, called MissForest, has been evaluated to fill the gap of daily streamflow series in a region with scarce data and strong climate variability. Methods: The daily streamflow data in the gauge stations of the Southern Baluchestan catchment were analyzed in a long-term hydrological period (09/23/1972 to 09/22/2018). First, the missingness percentage was selected based on a conventional criterion (less than 50%) as an acceptable ratio of the missing rate in the streamflow data, followed by investigating the mechanisms and patterns of the missing data. Accordingly, the number of gauge stations was reduced to seven samples. Then, the temporal distribution of the missing daily streamflows during the months of the year and the relative frequency of gap length were investigated during the period. Next, the performance of the missing data reconstruction algorithm was challenged with two different artificial missing data scenarios. Two types of artificial gaps were generated, namely a) Removed contiguous segments: at each gauge only a segment (having lengths of 7, 14, 21, 30, 60, 180, and 365 days) was randomly removed from the entire record (1972–2018); b) Removed single data points: observed values (30, 60, 90, 120, 180, and 365 days) were randomly removed from the entire record (1972–2018) at each of the gauges. MissForest was applied to fill the gaps contained in the records together with the artificial gaps. Our analysis includes reconstructions of the 1972–2018 period at each of the streamflow gauges. Finally, the performance of MissForest in infilling daily streamflow data was tested by comparing the filled series with the observed data using goodness-of-fit (GoF) indicators, coefficient of determination (R2 ), the percent bias (PBIAS), and the Kling-Gupta efficiency (KGE). Results: The MissForest algorithm generally performed satisfactorily, allowing for accurately and reliably simulating lost data quickly and automatically. The performance of the MissForest algorithm is highly dependent on the number of predictor records, record length, and streamflow type. Finally, the reconstruction of real gaps in streamflow data was possible by applying this intelligent algorithm. The river flow time series were simulated with the natural flow regime with good performance; however, this performance dropped slightly for flow rate changes as a result of water storage and diversion for irrigation, especially downstream of dams. The performance of this algorithm in filling the daily time series of flow with severe changes in the flow regime, such as peak discharge, was not evaluated optimally. This drop in performance is more related to the hydroclimatic conditions of the studied watershed than the structure of the algorithm. The reconstructed hydrographs allow for analyzing flow variability and their interaction with key climate variables. Conclusion: The MissForest algorithm is introduced as one of the imputation methods based on machine learning with high credibility and performance in reconstructing the missing data of the daily streamflow. It can also be used automatically and intelligently in the reconstruction of the statistical defects of the river flow in the scale used daily. Future studies are suggested to analyze the effects of different watersheds with specific hydro-physical-climatic characteristics on the performance of the MissForest algorithm. The other issues that need to be addressed in future studies include the investigation of the proposed method of this study in other climatic and geographical regions, the sensitivity measurement to the rainfall and flow regime, and finally, the investigation of its performance compared to other common methods