OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

This paper provides a summary of the work done within the OC6 Phase II project, which was focused on the implementation and verification of an advanced soil–structure interaction model for offshore wind system design and analysis. The soil–structure interaction model comes from the REDWIN project and uses an elastoplastic, macroelement model with kinematic hardening, which captures the stiffness and damping characteristics of offshore wind foundations more accurately than more traditional and simplified soil–structure interaction modeling approaches. Participants in the OC6 project integrated this macroelement capability to coupled aero-hydro-servo-elastic offshore wind turbine modeling tools and verified the implementation by comparing simulation results across the modeling tools for an example monopile design. The simulation results were also compared to more traditional soil–structure interaction modeling approaches like apparent fixity, coupled springs, and distributed springs models. The macroelement approach resulted in smaller overall loading in the system due to both shifts in the system frequencies and increased energy dissipation. No validation work was performed, but the macroelement approach has shown increased accuracy within the REDWIN project, resulting in decreased uncertainty in the design. For the monopile design investigated here, that implies a less conservative and thus more cost-effective offshore wind design.US Department of Energy Office of Energy Efficiency and Renewable Energy Wind Energy Technologies Office, Grant/Award Number: DE-AC36-08GO2830

OC6 project phase III : validation of the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure

This paper provides a summary of the work done within Phase III of the Offshore Code Comparison, Collaboration, Continued, with Correlation and unCertainty project (OC6), under International Energy Agency Wind Task 30. This phase focused on validating the aerodynamic loading on a wind turbine rotor undergoing large motion caused by a floating support structure. Numerical models of the Danish Technical University 10-MW reference wind turbine were validated using measurement data from a 1:75 scale test performed during the UNsteady Aerodynamics for FLOating Wind (UNAFLOW) project and a follow-on experimental campaign, both performed at the Politecnico di Milano wind tunnel. Validation of the models was performed by comparing the loads for steady (fixed platform) and unsteady wind conditions (harmonic motion of the platform). For the unsteady wind conditions, the platform was forced to oscillate in the surge and pitch directions under several frequencies and amplitudes. These oscillations result in a wind variation that impacts the rotor loads (e.g., thrust and torque). For the conditions studied in these tests, the system mainly described a quasi-steady aerodynamic behavior. Only a small hysteresis in airfoil performance undergoing angle of attack variations in attached flow was observed. During the experiments, the rotor speed and blade pitch angle were held constant. However, in real wind turbine operating conditions, the surge and pitch variations would result in rotor speed variations and/or blade pitch actuations depending on the wind turbine controller region that the system is operating. Additional simulations with these control parameters were conducted to verify the fidelity between different models. Participant results showed in general a good agreement with the experimental measurements and the need to account for dynamic inflow when there are changes in the flow conditions due to the rotor speed variations or blade pitch actuations in response to surge and pitch motion. Numerical models not accounting for dynamic inflow effects predicted rotor loads that were 9 % lower in amplitude during rotor speed variations and 18 % higher in amplitude during blade pitch actuations

Simulation of a Wind Powered Freshwater and Electricity Production System: Numerical Modeling and Optimization

The rapid growth in world population and increasing demands have led to the lack of fresh water, taking a toll on several of earths reserves, mainly the fresh water supply reserves. Water stress deters economic growth, leads to conflicts and has a direct impact on the health of humans. Studies show the trends in theincrease of water consumption per capita due to increase in higher standards of living over the last years, resulting in the decrease of usable high purity water. 97% of the world’s water supply is locked in the salted, often unusable oceans. In recent times, water stressed countries are using the saline water from the oceans and desalinating it to produce fresh water for domestic, industrial or agricultural use. The state-of-the art method for desalinating saltwater is by Reverse Osmosis (RO). The biggest drawback of this technology is its high energy consumption mostly provided by conventional sources like fossil fuels. Therefore, for a sustainable future, a renewable energy source must be integrated to power the RO system.Delft Offshore Turbine (DOT) is currently developing and testing a new hydraulic drive train solution for fluid power transmission in offshore wind turbines using seawater as the medium. A hydraulic positive displacement pump is driven by the DOT wind turbine creating a flow of sea water under high pressure. This high-pressure flow can be either directed to a RO unit to desalinate seawater or converted into electricity using a spear valve and pelton turbine generator. A major challenge while using wind as an energy source is its intermittency. Reverse osmosis plants are designed to operate at a fixed flow and pressure while due to the uncontrolled, varying nature of the wind, the pump output experiences fluctuations in both pressures and flows.The aim of this thesis is to analyze the steady-state behavior of the integrated system for wind speeds up to the turbine rated wind speed under different operating conditions. This is achieved by simulating the behavior of the DOT500 hydraulic drive train wind turbine coupled to a RO system with pressure exchanger energy recovery device and a nozzle with a pelton turbine generator. The main objective of this research is to build a numerical model in Python using algorithms to solve the system of steady-state equations and optimize the integrated system for maximum water and maximum electricity production at specified locations.The numerical model is simulated for all combinations of wind speeds and nozzle positions and the behavior of the high-pressure pump, RO system, pelton turbine and various system parameters are shown. A sensitivity study is performed for important desalination parameters and their effect on system performance is analyzed.This research has yielded three main conclusions / deliverables:1. Behavior of the wind powered integrated system to produce freshwater and electricity at different operating conditions.2. Steady state control of DOT500 turbine and behavior of the pelton turbine to produce either maximum electricity or maximum water.3. Sensitivity of important desalination system parameters on overall system behavior for future optimization of RO membranes.Electrical Engineering | Sustainable Energy Technolog

Celebrating 75 Years of India’s S&T Journey Major Recent Contributions of DST

16-23DST has played a pivotal role in coordinating and integrating S&T areas across the ministries and associated departments, S&T institutions, academia, and industry, regionally and globally

OC6 Phase II: Integration and verification of a new soil–structure interaction model for offshore wind design

This paper provides a summary of the work done within the OC6 Phase II project, which was focused on the implementation and verification of an advanced soil–structure interaction model for offshore wind system design and analysis. The soil–structure interaction model comes from the REDWIN project and uses an elastoplastic, macroelement model with kinematic hardening, which captures the stiffness and damping characteristics of offshore wind foundations more accurately than more traditional and simplified soil–structure interaction modeling approaches. Participants in the OC6 project integrated this macroelement capability to coupled aero-hydro-servo-elastic offshore wind turbine modeling tools and verified the implementation by comparing simulation results across the modeling tools for an example monopile design. The simulation results were also compared to more traditional soil–structure interaction modeling approaches like apparent fixity, coupled springs, and distributed springs models. The macroelement approach resulted in smaller overall loading in the system due to both shifts in the system frequencies and increased energy dissipation. No validation work was performed, but the macroelement approach has shown increased accuracy within the REDWIN project, resulting in decreased uncertainty in the design. For the monopile design investigated here, that implies a less conservative and thus more cost-effective offshore wind design