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Browsing by Author "Deldar, Majid"
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Item Analysis of a hydrostatic drive wind turbine for improved annual energy production(AIMS Press, 2018-10-21) Deldar, Majid; Izadian, Afshin; Anwar, Sohel; Department of Mechanical and Energy Engineering, School of Engineering and TechnologyThis paper presents an analysis on ways to improve the annual energy production (AEP) of a wind turbine utilizing a drivetrain that operates based on the hydrostatic transmission. The system configuration of such a drivetrain is explained in details and a comparison of operation and characteristics with existing drivetrains is provided. AEP was estimated for these configurations through appropriate dynamic modeling and operational efficiency optimization. Optimal selection of a number of design variables and system parameters contributed to the improvements in the AEP. Findings of this study demonstrate that the proposed hydrostatic drivetrain improves the AEP of a 750 kW turbine by up to +8% when compared with a geared wind turbine. The AEP improvements of the hydrostatic drive wind turbine were more than 10% for a 1.5 MW system over geared configuration. It is also demonstrated that the efficiency of power generation can be improved under various wind speeds. The suitable selection of synchronous speed of the generator directly improves the efficiency of operation by up to 35% at low wind speeds. An efficiency improvement was also observed under higher operating pressures and longer turbine blades.Item Analysis of a hydrostatic drive wind turbine for improved annual energy production(AIMS, 2018) Deldar, Majid; Izadian, Afshin; Anwar, Sohel; Mechanical Engineering and Energy, School of Engineering and TechnologyThis paper presents an analysis on ways to improve the annual energy production (AEP) of a wind turbine utilizing a drivetrain that operates based on the hydrostatic transmission. The system configuration of such a drivetrain is explained in details and a comparison of operation and characteristics with existing drivetrains is provided. AEP was estimated for these configurations through appropriate dynamic modeling and operational efficiency optimization. Optimal selection of a number of design variables and system parameters contributed to the improvements in the AEP. Findings of this study demonstrate that the proposed hydrostatic drivetrain improves the AEP of a 750 kW turbine by up to +8% when compared with a geared wind turbine. The AEP improvements of the hydrostatic drive wind turbine were more than 10% for a 1.5 MW system over geared configuration. It is also demonstrated that the efficiency of power generation can be improved under various wind speeds. The suitable selection of synchronous speed of the generator directly improves the efficiency of operation by up to 35% at low wind speeds. An efficiency improvement was also observed under higher operating pressures and longer turbine blades.Item Configuration Analysis and Design of a Wind Turbine With Hydrostatic Transmission System(ASME, 2016-11) Deldar, Majid; Izadian, Afshin; Anwar, Sohel; Mechanical Engineering, School of Engineering and TechnologyThis paper presents a methodology for designing and dimensioning of hydrostatic transmission system (HTS) configurations for wind turbines. HTS provides an alternative method to the gearbox in wind power applications. It decouples the turbine and the generator such that the generator can be driven at synchronous speed regardless of wind speed variation. A comparison of different HTS configurations shows that the functionality and performance of the proposed system depends on proper dimensioning of hydraulic components and the circuit configuration. Practical constraints of wind turbine and hydraulic technologies are considered in the design to configure an industrial scale system. The design objectives include obtaining the maximum system efficiency at the rated and high efficiency at partial load. Different hydrostatic systems were designed and simulated to show potentials for improving the overall efficiency of wind power using HTS. It was shown that the larger swept area and moderate speed generator improve efficiency of hydrostatic drivetrain. Optimization of the entire HTSWT can improve output power from a HTSWT to an extent that its annual energy production (AEP) becomes closely equal to AEP of a geared WT.Item Modeling of a Hydraulic Wind Power Transfer Utilizing a Proportional Valve(IEEE, 2015-03) Deldar, Majid; Izadian, Afshin; Vaezi, Masoud; Anwar, Sohel; Department of Mechanical Engineering, School of EngineeringHydraulic circuits can transfer remarkable amounts of energy in the desired direction without taking large space. To implement this technology for harvesting the energy of wind appropriately, models of the system are required. Hydraulic wind power technology has the benefits of eliminating expensive and bulky variable ratio gearbox and its costly maintenance, while enabling the integration of multiple wind turbines in a single generation unit. In this paper, the dynamics of different hydraulic elements are studied, nonlinearities are taken into account, pressure dynamics in different parts of the system are studied, and the motor load effects are considered. Based on these considerations, a novel nonlinear state-space representation of the system is introduced. Results of the mathematical model and the experimental data are compared to verify the proposed model. The comparison demonstrated that the mathematical model captures all major characteristics of the hydraulic circuit and can model the system behavior under different operating conditions.Item Nonlinear State Space Model of a Hydraulic Wind Power Transfer(Office of the Vice Chancellor for Research, 2013-04-05) Vaezi, Masoud; Deldar, MajidGearless hydraulic wind power systems are considered as nonlinear models because of some discrete elements such as check valves, proportional and directional valves, and leakage factor of hydraulic pumps and motors. These Nonlinearities will result in behavioral change in the system. This poster introduces nonlinear governing equations for the elements in the proposed hydraulic wind power configuration. Nonlinear state space representation of a hydraulic wind energy transfer for a single wind turbine system is presented. Simulation results are in good agreement with the experimental verifications obtained from prototype. The simulation response demonstrates accurate modeling of the system operation and close tracking of the reference for all states, pressure and pelocity profiles.Item Optimal Control of Hydrostatic DriveWind Turbines for Improved Power Output in LowWind-Speed Regions(MDPI, 2021) Ali, Ammar E.; Deldar, Majid; Anwar, Sohel; Mechanical and Energy Engineering, School of Engineering and TechnologyWorld wind energy output is steadily increasing in both production scale and capacity of harvesting wind. Hydrostatic transmission systems (HTSs) have been used mostly in offshore wind turbine applications. However, their potential has not been fully utilized in onshore wind turbines, partially due to concerns related to hydraulic losses. In our prior work, it was shown that the annual energy production from a hydrostatic wind turbine can match or exceed that of a mechanical drive wind turbine with appropriate optimal control techniques. In this paper, we present an optimal control technique that can further improve energy production of a hydrostatic wind turbine, particularly in low speed regions. Here, the overall loss equation of the HTS is developed and used as a cost function to be minimized with respect to system model dynamics. The overall loss function includes the losses due to both the aerodynamic efficiencies and the hydrostatic efficiencies of the motor and pump. A nonlinear model of HST is considered for the drive train. Optimal control law was derived by minimizing the overall loss. Both unconstrained and constrained optimization using Pontryagin’s minimum principle were utilized to derive two distinct control laws for the motor displacement. Simulation results showed that both the controllers were able to increase power output with the unconstrained optimization offering better results for the HTS wind turbine in the low speed regions (3–8 m/s).Item Reconfiguration of a Wind Turbine with Hydrostatic Drivetrain to Improve Annual Energy Production(IEEE, 2015-09) Deldar, Majid; Izadian, Afshin; Anwar, Sohel; Department of Mechanical Engineering, School of Engineering and TechnologyAbstract: Hydrostatic transmission systems (HTS) have shown potential in replacing gearbox in conventional wind turbines. However, the general perception about these systems is that they suffer from low efficiencies, specifically at low wind speeds. This paper presents a novel technique that can improve the annual energy production (AEP) beyond that of a conventional wind turbine. By optimizing the operating conditions and the design of the wind turbine, the performance and efficiency of a HTS can be improved. A side-by-side comparison with the conventional wind turbines is provided to highlight the benefits of the proposed methodology. One of the findings of this research is that, rotor, hydrostatic pump, motor and their operations' planning must be optimized together to achieve higher AEP. The reconfigured turbines are shown to provide up to 8 percent AEP increase for a 750 kW plant and up to 10 percent increase for 1500 kW plants using the proposed drivetrain configurations.