Browsing by Author "Marjan, Ali"

Now showing 1 - 4 of 4
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    Evaluation of wind resources and the effect of market price components on wind-farm income: a case study of Ørland in Norway
    (MDPI, 2019-10-29) Marjan, Ali; Shafiee, Mahmood
    This paper aims to present a detailed analysis of the performance of a wind-farm using the wind turbine power measurement standard IEC61400-12-1 (2017). Ten minutes averaged wind data are obtained from LIDAR over the period of twelve months and it is compared with the 38 years’ data from weather station with the objective of determining the wind resources at the wind-farm. The performance of one of the wind turbines located in the wind-farm is assessed by comparing the wind power potential of the wind turbine with its actual power production. Our analysis shows that the wind farm under study is rated as ‘good’ in terms of wind power production and has wind power density of 479 W/m2. The annual wind-farm’s income is estimated based on the real-data collected from the wind turbines. The effect of price of electricity and the spot prices of Norwegian-Swedish green certificate on the income will be illustrated by means of a Monte-Carlo Simulation (MCS) approach. Our study provides a different perspective of wind resource evaluation by analyzing LIDAR measurements using Windographer and combines it with the lesser explored effects of price components on the income using statistical tools.
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    Impact of design parameters on the dynamic response and fatigue of offshore jacket foundations
    (MDPI, 2022-09-18) Marjan, Ali; Hart, Phil
    The lifetime of offshore foundations is governed by a combination of harsh environmental conditions and complex service loads. The fatigue limit state (FLS) analysis needs to be performed in the time domain to capture the complex phenomenon. This study aims to investigate different parameters and design modifications that can impact the design life of an offshore jacket foundation. An OC4 jacket foundation is designed in industrial software from DNV and reduced to a super-element model. The super-element model is connected to an NREL 5-MW wind turbine designed in Bladed. The time-series loads are used to compute the fatigue damages faced by the foundation during the service life. The impact of soil non-linearity, marine growth, scour size, the mass of the transition piece, and the grouted connection’s design on the dynamic response and fatigue damages are compared. A 30% increase in life was observed by replacing the concrete transition piece with a lightweight steel configuration. The fatigue damages were considerably greater for the inclined pile in the leg grouted connection than for the leg in the pile concept. The study provides a different perspective by analysing the effect of design parameters and design changes in the complex and computationally expensive time-series domain.
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    Structural fatigue assessment and optimisation of offshore wind turbine jacket foundations.
    (Cranfield University, 2023-08) Marjan, Ali; Huang, Luofeng; Hart, Phil
    Offshore Wind Turbine (OWT) is an expensive type of renewable energy system, and there is a continuous effort to lower the capital and operational costs. Jacket foundations are increasingly used in offshore wind due to their relatively light weight and adaptability in deep waters. However, the contemporary jacket designs are based on conservative practices from the oil and gas industry. There is still substantial room to optimise the jacket designs for offshore wind usage. This research aims to generate innovative jacket designs by applying a topology optimisation algorithm. The research demonstrates the use of advanced computational techniques to improve existing designs by enhancing structural integrity and fatigue life whilst reducing the mass. The research presents a comprehensive investigation of different parameters and design modifications that impact the design life of an existing jacket. An OC4 jacket foundation is employed, modelled in industrial software from DNV, and transformed into a super element model. The time-series loads obtained from Bladed are used to assess fatigue damages experienced during the foundation's service life. Furthermore, the research presents a topology optimisation method to retrofit an existing jacket foundation design by finding the optimum load path on the structure to enhance fatigue life and lower costs. The jacket's structural optimisation is performed by considering its dynamic response while adhering to the relevant international design standards. In particular, time-domain fatigue simulations were performed to assess the structural integrity of the topology- optimised jacket for the first time. As a result, a range of optimised models with various thickness and diameter options are presented, which are shown to be rational and verify the optimisation procedure. The research contributes a unique integrated topology optimisation framework, dynamic analysis, and time-domain fatigue simulations using industry-standard software tools, and achieved a mass reduction of 35.2% and simultaneously realized a 37.2% better fatigue life compared to the baseline model. The overall environmental load calculation, optimisation procedure and results provide useful practicalities for designing offshore wind turbine foundations and potentially facilitate the relevant industry's structural integrity and cost reduction.
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    Topology optimisation of offshore wind turbine jacket foundation for fatigue life and mass reduction
    (Elsevier, 2023-11-06) Marjan, Ali; Huang, Luofeng
    Offshore wind turbines are frequently regarded as a pricey source of electricity, and efforts are being made to lower both capital and operational costs by developing lighter and more robust structures. This paper presents a topology optimisation method to obtain a novel jacket foundation design by finding the optimum load path on the structure. The OC4 jacket model was computationally simulated considering the Aero-Hydro-Servo-Elastic loads, and the topology optimisation method was used to obtain a series of new designs. The structural optimisation is performed based on the dynamic response of the jacket, whilst restrained by relevant international design standards. In particular, time-domain fatigue simulations were performed to assess the structural integrity of the topology-optimised jacket for the first time. As a result, a range of optimised models with various thickness and diameter options are presented, which are shown to be rational and verify the optimisation procedure. The structural performance of the optimised geometry demonstrates the original jacket foundation is conservative, and the selection of optimised geometry achieved a mass reduction of 35.2% and simultaneously realised a 37.2% better fatigue life. The overall optimisation procedure and results provide useful practicalities for the design of offshore wind turbine foundations and potentially facilitate the structural integrity and cost reduction of the relevant industry.