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  • 1.
    ahmad, waqas
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Development of algorithm for li-ion batteries in electric vehicles, taking into account SOC, charge control, cell balancing and SOF.2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
  • 2.
    Ahmed, Faisal Mahmood
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Estimated Droop Control for Parallel Connected Voltage Source Inverters: Stability Enhancement2013Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Renewable Energy Sources (RES) are considered as the replacement of conventionalenergy sources. These RES can use wind energy, solar light, bio waste and can alsobe in the form of small hydro power units. These RES has very poor power qualityand contains voltage uctuations and variable frequency. These factors make RES astability risk for the main utility grid. As a solution, currently inverters with dierentdesign techniques are being used as an interface between RES and main utility grid. Thecurrent study proposed a new technique "estimated droop control" for inverter design.The conventional droop control technique which was already used in inverter design, hasdiculty in synchronizing parallel connected inverters with dierent droop gains and lineimpedances. The proposed "estimated droop control" does not use any predened droopvalues for inverters and all inverters are responsible for the estimation of their own droopvalues with respect to their output power. Therefore, inverters are not bound to usesame and static droop values which are considered as a vital communication link. Theproposed design methodology has made inverters independent from this only virtual linkof communication due to which the reliability of a system has increased. The proposeddesign technique has given very good results in a simulation run. When the Simulinkmodel was run in parallel connected inverter with dierent line impedances, it was asuccess as both inverters started operating with same droop values as they were sharingan equal load. The most important test was with dierent line impedances because inconventional droop control it is dicult for inverters to keep their synchronism withdierent line impedances and an unequal load sharing make inverters to deviate fromtheir nominal values and to generate dierent tracking signals for each set. This problemhas been successfully solved with estimated droop control as in this method each inverterset its droop gains according to its output power, which helps an inverter to operate atnominal values with dierent droop gains and line impedance.

  • 3.
    Ahmed, Umair
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Racing Driver Model in Dymola Vehicle Dynamics Library (VDL): Steering Controller Design2012Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Racing drivers always want to traverse path at vehicle’s maximum performance limits while keeping the vehicle at its ideal trajectory. The main objective of this report is to elaborate strategy for the path following problem in which driver has to follow the predefined 2D roads. New steering controller design for closed loop racing driver model in Dymola vehicle dynamics library is developed. The methodology proposed by Sharp et al. [2] is followed with the optimal velocity profile that tries to mimic the actions of the real drivers in real time scenarios. Vehicle handling limits i.e. longitudinal and lateral limits are defined before simulation. While travelling in the neighbourhood of optimal velocity on the straight road as well as during the curves, the performance of the steering controller is tested by conducting the test on J turn, Clothoid, Extended chicane and the closing curve path and also tested during the different environment effects e.g. when there is a side wind affecting the vehicle. Performance of existing and new steering controllers discussed and compared in result chapter. It is ensured that the drawbacks in the existing steering controller are eliminated by using the proposed methodology in new implemented steering controller.

    Key Words: Driver Model, Steering Controller, Path following, Velocity profile

  • 4.
    Aimal, Pir
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics.
    Mohsin, Main
    Analyzing Voltage control and reactive power support from full power converter wind turbine2011Independent thesis Advanced level (degree of Master (Two Years)), 80 credits / 120 HE creditsStudent thesis
  • 5.
    Beri, George
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Prediktering och styrning av värmesystem i flerbostadshus: Utvärdering av egenutformad MPC-regulator2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In 2012, 30% of the total energy consumption was used by apartments and buildings. Heating of apartment buildings and commercial buildings represents 60% (79.5 TWh) of that energy consumption. There is thus great potential for reducing energy use in the residential sector. Part of the overall efficiency work is to review the control of heating systems. Today's control often involves simple on / off systems where an upper and lower limit controls when to start and stop a process. This form of control is therefore best suited to systems where the change of state occurs quickly. When it comes to homes with high mass however, it takes time before a change takes effect. In some cases, it can take up to 24h before a change is noticed for buildings with high thermal inertia. An alternative to the traditional temperature based control is the so-called MPC controller which stands for Model Predictive Control. MPC is a control method that can take into account the thermal inertia and the dynamics of buildings. MPC controller also controls the system proactive rather than retroactive, which is the technique most of current control methods use. One problem with the MPC controller thou is that it requires large computational resources and technical knowledge of the building where it will be implemented. The aim of the thesis was to design a simple MPC controller and evaluate its performance. This was done by constructing a bench test model that can evaluate the function of the MPC controller. In addition to constructing a simple MPC-controller, a study has been done on how the current control method can be more energy efficient without having to invest in new equipment. The goal was to reduce the variations in indoor temperature and improve operating economics of the building. The study was conducted at Karlstad Bostads Aktiebolag (KBAB) that owns and manages 7,300 apartments in Karlstad. The Bench test model calculated indoor temperature using the weather conditions as solar radiation, cloud cover, outside temperature and wind speed. The study presents a number of simple MPC controllers that can be used to minimize indoor temperature variations and improving operating economy. It is estimated, however, that the MPC controller that only takes into account the outside temperature in its prediction is the most appropriate. The MPC controller has the potential to reduce heating requirements by 3.12 MWh (-4%) and reduce indoor temperature variations with 96%. The mean annual temperature would be 21.1 ° C and the energy consumption 113 kWh/m2 for the building. The study also presents an alternative to current control method that does not require any additional resources or investments. It has the potential to reduce heating requirements by 8.3 MWh (10%) and reduce indoor temperature variations by 65%. The energy consumption would then be 106 kWh/m2.

  • 6.
    Borregales, Manuel
    et al.
    University of Bergen, Norway..
    Radu, Florin A.
    University of Bergen, Norway..
    Kumar, Kundan
    University of Bergen, Norway.
    Nordbotten, Jan M.
    University of Bergen, Norway.; Princeton University, USA..
    Robust iterative schemes for non-linear poromechanics2018In: Computational Geosciences, ISSN 1420-0597, E-ISSN 1573-1499, Vol. 22, no 4, p. 1021-1038Article in journal (Refereed)
    Abstract [en]

    We consider a non-linear extension of Biot's model for poromechanics, wherein both the fluid flow and mechanical deformation are allowed to be non-linear. Specifically, we study the case when the volumetric stress and the fluid density are non-linear functions satisfying certain assumptions. We perform an implicit discretization in time (backward Euler) and propose two iterative schemes for solving the non-linear problems appearing within each time step: a splitting algorithm extending the undrained split and fixed stress methods to non-linear problems, and a monolithic L-scheme. The convergence of both schemes are shown rigorously. Illustrative numerical examples are presented to confirm the applicability of the schemes and validate the theoretical results.

  • 7.
    Cheema, Umer Ali
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. RWTH Aachen University, Germany..
    Design of a State of Charge (SOC) Estimation Block for a Battery Management System (BMS).2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Battery Management System (BMS) is an essential part in battery powered applications where large battery packs are in use. BMS ensures protection, controlling, supervision and accurate state estimation of battery pack to provide efficient energy management. However the particular application determines the accuracy and requirements of BMS where it has to implement; in electric vehicles (EVs) accuracy cannot be compromised. The software part of BMS estimates the states of the battery pack and takes the best possible decision.

    In EVs one of the key tasks of BMS’s software part is to provide the actual state of charge (SOC), which represents a crucial parameter to be determined, especially in lithium iron phosphate (LiFePO4) batteries, due to the presence of the high hysteresis behavior in the open circuit voltage than other kind of lithium batteries. This hysteresis phenomena appears with two different voltage curves during the charging and discharging process. The value of the voltage that the battery is going to assume during the off-loading operation depends on several factors, such as temperature, loop direction and ageing.

    In this research work, hybrid method is implemented in which advantages of several methods are achieved by implementing one technique combined with another. In this work SOC is calculated from coulomb counting method and in order to correct the error of SOC, an hysteresis model is developed and used due to presence of hysteresis effect in LiFePO4 batteries. An hysteresis model of the open circuit voltage (OCV) for a LiFePO4 cell is developed and implemented in MATLAB/Simulink© in order to reproduce the voltage response of the battery when no current from the cell is required (no load condition). Then the difference of estimated voltage and measured voltage is taken in order to correct the error of SOC calculated from coulomb counting or current integration method. To develop the hysteresis model which can reproduce the same voltage behavior, lot of experiments have been carried out practically in order to see the hysteresis voltage response and to see that how voltage curve change with the variation of temperature, ageing and loop direction. At the end model is validated with different driving profiles at different ambient temperatures.

  • 8.
    Faessler, Florian Markus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Iterative Learning Control of Fast Switching On/Off Valves in Digital Hydraulic Drives2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Time delays in control systems diminish performance or even cause instability. Additionally, inherent model errors occurring in model based control approaches yield undesired system behavior and further reduce performance. An example of such a system is the digital hydraulic radial piston motor where several cylinders actuated by valves contribute to the output torque. The systems complexity makes precise system modeling difficult and valves to actively control in- and outflow of the cylinders cause undesired delays.

    In this work an iterative learning control(ler) (ILC) approach is presented to compensate model uncertainties of the higher level optimal controller and delays caused by the valves. Due to the use of on/off valves discrete inputs are considered. First a detailed valve model is derived for a solenoid on/off valve for the use in simulations. Missing parameters are estimated. The derived model and the estimated parameters accurately describe the valve response. Comparing the model response with measurement data shows this. Iterative learning control is then used to compensate delays and model errors of the system with binary control inputs, varying iterations length and changing reference trajectories. Simulations and hardware-in-the-loop (HIL) experiments show that the method can reliably compensate valve delays and to some extend model uncertainties.

  • 9.
    Irshad, Yasir
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Mossberg, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    A comparison of estimation concepts applied to networked control systems2012In: 19th International Conference on Systems, Signals and Image Processing (IWSSIP), 2012, Piscataway: IEEE Press, 2012, p. 114-117Conference paper (Refereed)
    Abstract [en]

    A continuous-time description of networked control systems is considered and the parameters are estimated. The discrete-time description is time-varying due to the random time-delays in the wireless links and therefore difficult to work with. Off-line as well as on-line situations are considered for parameter estimation. In the off-line situation, a linear regression is formed and then the parameters are estimated by the least squares method. In the on-line situation, the estimates of the parameters are recursively updated for each time instance. A comparative study of two different parameter estimation approaches is presented. In the first approach, the parameters are estimated by a simple linear regression. In the second approach, transformation of the differentiation operator to another casual and stable linear operator is made in linear regression to estimate the parameters. A numerical study of these approaches is also presented for comparison.

  • 10.
    Johansson, Alexandra
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Lagring av industriell överskottsvärme hos Bharat Forge Kilsta i Karlskoga: Simulering av värmeförluster och regleringsundersökning2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    When the population increases also the energy use will rise. At the same time the nuclear power plants is decommissioned and the use of coal-fired power plants increases, which leads to large amount of mainly carbon dioxide emissions.

    Many industries get a lot of excess heat that is released in the nature instead of being reused. One way to reuse excess heat could be to store the heat in a suitable storage for later use. If the excess heat can be stored and be used at a different time it can replace other energy sources and decrease the emissions. Today there is three ways to storage heat, they are sensible heat, latent heat, and chemical heat. In each method there are different systems, these will be described further in this report.

    Bharat Fore is a large forging company in Karlskoga, Sweden. From their furnace a lot of heat is emitted, some of the heat is used to heat the buildings, but still a lot of excess heat goes to waste.  The aim of this report is to compare different heat storage systems and see which one is best suited to industrial excess heat. The goal is to investigate if there is any heat storage method that is effective and cost-saving that fits a larger industry.

    The purpose of this work is to do a literature study to account and compare different heat storage methods to find the best suitable system for the case with Bharat Forge Kilsta. The goal is to present different storage methods and the different system for each method with respect of cost and storage capacity. From simulation and regulation find the best fitting method for the real case with respect of cost, efficient and storage capacity.

    The most developed and commercially used method is the sensible heat. Latent heat and chemicals are very costly and still in the research and development stage. Geographic location, using area and operating temperature is parameters that need to be considered when choosing heat storage system. Sensible heat is best suited for long-term storage, at lower temperatures and when the storage capacity needs to be large to a small cost. Latent and chemical heat is best suited for higher temperatures because the heat losses are small and the energy density is high and they are only applied in small scale for now.

    The result of the literature study showed that storage tanks and cavern storage is most fitting for the case with Bharat Forge Kilsta.

    The cavern has much larger heat loss compared to the total energy, however the storage capacity is much larger. To guarantee that the heat requirements when there are extreme days it is most appropriate to use the cavern as heat storage. From a coast view it is most fitting to use the already existing tanks, however they could only cater the heat requirement for six hours of heat peak when the production is not running.

    If the existing tanks is used as heat storage, and the 200 m3 tank will be additional insulated, if the heat loss, in the winter, is replaced with purchased district heating as much as 100 000 SEK per year could be spared.

    The payback time is shortest for the existing tanks, 1.4 years and almost 3.2 years for the new storage tank.

  • 11.
    Johansson, Simon
    Institutionen för ingenjörsvetenskap och fysik.
    Reglering av drönare vid viktbelastning2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This project tested how a drone can be controlled when loads are applied to it. First four different control methods were analyzed, two model based and two non-model based. The two model based were linear quadratic regulator and model predictive control. The two non-model based were cascade control and PID regulator. The PID regulator were chosen and three different methods to tune the PID was tested. Ziegler-Nichols, lambda and AMIGO method, all used the step response from the system to determine the parameters. These different methods gave different setup of parameters and the best result came from the AMIGO method. The different loads that were applied to the system was 4.7, 6.1 and 10.8 gram. The AMIGO method were able to tune the PID up to 6.1 grams, then the system lost to much of its linear behavior. To summarize the work a PID tuned by the AMIGO method using the step response were able to control a drone with a load up to about six grams. 

  • 12.
    Khalid, Areeb
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics. RWTH Aachen University Germany.
    Design of an Aging Estimation Block for a Battery Management System (BMS):  2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 13.
    Magnusson, Sven
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Bladh, Henrik
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Framtagning av reglerparametrar i badvattenreningsanläggningar2012Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
  • 14.
    Mossberg, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Spectral density based estimation of continuous-time ARMAX process parameters2012In: Asian journal of control, ISSN 1561-8625, E-ISSN 1561-8625, Vol. 14, no 2, p. 548-552Article in journal (Refereed)
    Abstract [en]

    The continuous-time ARMAX model is a standard model that can be used for describing continuous-time stochastic dynamic systems for control purposes. In this note, the problem of estimating the parameters in such a model from discrete-time data is considered. In the proposed solution, the parameters in the denominator polynomial are estimated using a continuous-time Yule-Walker equation. Thereafter, the parameters in the numerator polynomials are estimated using an approach based on the spectral density of the output signal and regularized least squares. The method is sub-optimal but easy to apply and the given estimates can be used directly or as initial values for the maximum likelihood method

  • 15.
    Mossberg, Magnus
    et al.
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Mossberg, Eva
    Karlstad University, Faculty of Technology and Science, Department of Mathematics.
    A Note on Parameter Estimation in Lamperti Transformed Fractional Ornstein-Uhlenbeck Processes2012In: IFAC Proceedings Volumes / [ed] Kinnaert, Michel, Elsevier, 2012, Vol. 45/16, p. 1067-1072Conference paper (Refereed)
  • 16.
    Rust, Josefine
    Karlstad University, Faculty of Health, Science and Technology (starting 2013).
    Testsystem för processtyring2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Målet med det här arbetet var att implementera och bygga ett komplett testsystem för reglering som efterfrågades av företaget Prevas AB i Karlstad. De önskade ett testsystem som reglerar en vattentemperatur som de kan använda på kontoret för att genomföra egna tester, analyser samt lära nyanställda medarbetare mer om automation. Testsystemet har även ett tillhörande HMI (Machine Human Interface) som användaren styr regleringen ifrån.

    Regleringen i testsystemet använder PID(Proportional–integral–derivative)-reglering och är inställd med lambdametoden. PID-reglering är den vanligaste använda metoden inom tillverkningsindustrin för reglering, men trots det är det många av dagens PID-regleringar som underpresterar. En anledning är slitage i mekaniska ställdonen som finns i processerna. För att utvärdera att testsystemet fungerar samt för att visa vad det kan användas till, har en mindre analys av ett mekaniskt ställdon genomförts, där antalet tillslag för ett ställdon i det byggda systemet undersökts.

    Testsystemet som byggdes uppfyller de krav som ställts från Prevas och de är nöjda med resultatet. Analysen som genomfördes visade att testsystemet fungerade och kan användas till den typen av test. Analysen i sig visade att simulationen som implementerats i testsystemet inte fungerade som den skulle och därmed är några testresultat ogiltiga.

    Rapporten presenterar hur ett testsystem för reglering kan implementeras och sedan vad det kan användas till.

  • 17.
    Söderström, Torsten
    et al.
    Uppsala University.
    Irshad, Yasir
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Mossberg, Magnus
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering. Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Physics (from 2013).
    Zheng, Wei Xing
    University of Western Sydney.
    Accuracy analysis of a covariance matching method for continuous-time errors-in-variables system identification2012In: : IFAC Proceedings Volumes, Elsevier, 2012, Vol. 45, p. 1383-1388Conference paper (Refereed)
  • 18.
    Teshome, Teshome Delellegn
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    3-D Gesture Based Module for an Intelligently Controlled Service Robot Using a Motion Sensor2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The study of gesture recognition based sensing modalities for the purpose of Human-Robot Interaction (HRI) has had favorable success as of late - but most often at the expense of loss of naturalness on used gestures due mostly to use of awkward and bulky recognition system, lack of real-timeliness, and static condition requirements. However, some recent advancements in Natural User Interfaces by the industry and research community has helped produce new and interesting products, like the Kinect from Microsoft, that have captivated the attention of roboticits in its intended use for HRI. Coupled with the advent of artificial intelligence and machine learning that have bases in soft computing paradigms, the potential of these natural user interfaces is even more amplified.

    The aim of this thesis is to design and implement a 3-D gesture based recognition system capable of working on a mobile platform, and incorporate this interface as part of a mobile service robot that is able to navigate its environment reasonably well, while interacting and putting into action commands made by its human user. The fundamental distinction of this work as compared to the previous related works is the ability to recognize 3-D pose and motion gestures made in static and dynamic condition; at the same time being used for HRI by a service robot.

    The gesture recognition module is implemented by Time Delay Neural Network (TDNN) that has been trained to recognizing 3-D motion patterns from gesture sequences captured via the motion sensor, Kinect. The design of navigation control system of the service robot is undertaken using a Layered Behavior-based Control Architecture consisting of three layers, namely supervision layer, Behavioral layer, and locomotion layer. Fuzzy logic is used for designing robust individual behaviors as well as for behavior arbitration and fusion, while a two-degree-of-freedom PID control takes care putting into action desired locomotion commanded.

    Experiments aimed at verifying the performance of the gesture recognition module show an average recognition rate of 94.45% for a training dataset, where as a 91.06% average recognition rate for a previously unseen testing dataset. For gestures performed under both static and dynamic conditions, such results are as expected and deemed satisfactory as per the design specifications. In an attempt to showcase the application of the implemented 3-D gesture recognition perceptual module and its integration into the layered behavior-based control architecture, a series of tests were performed that serve as navigation and task execution examples. The results show the service robot interacting and performing simulated task scenarios to varying degrees of success; but all in all, the results were encouraging based on design specifications and the work scope put forth at the onset of the project work.

  • 19.
    Theocharis, Andreas
    et al.
    University of Patras, Patras, Greece.
    Zacharias, Thomas
    University of Patras, Patras, Greece.
    Tsanakas, Dimitrios
    University of Patras, Patras, Greece.
    Milias-Argitis, John
    University of Patras, Patras, Greece.
    Μodeling of a Grid Connected Photovoltaic System Using a Geometrical Transformer Model2009In: Zeszyty Problemowe – Maszyny Elektryczne, Katowice: Komel , 2009, Vol. 84Conference paper (Refereed)
  • 20.
    zafar, syed hammad
    Karlstad University, Faculty of Technology and Science, Department of Physics and Electrical Engineering.
    Modelling and control of large wind turbine2013Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In order to make the wind energy an economical alternative for energy production, upscaling of turbine to 10 - 15MW may be necessary to reduce the overall cost of energy production. This production target requires a considerable increase in the turbine size and placing the turbines at high wind speed locations. But increase in turbine size also increases the uneven load distribution across the turbine structure. Therefore an efficient load reduction technique is necessary to increase the turbine reliability in high wind speed locations. Variable speed wind turbine offers most desirable load reduction through actively pitch angle control of turbine blades. Research has shown that the Individual Pitch Control (IPC) is most promising option for turbine load reduction.

    This thesis work is focused on modelling of a large wind turbine and implementation of a new mutlivariable control concept for turbine load reduction. A detailed mathematical model is designed which includes turbine blade and tower dynamics and a proposed Linear Quadratic Gaussian (LQG) algorithm is implemented for Individual Pitch Control (IPC) loop of wind turbine. Proposed model in this thesis work is derived from the previous turbine model used in ECN with additional tower dynamics. My contribution in turbine modelling portion is to linearize the equations of motion to form a statespace model and to implement LQG algorithm for turbine active load reduction. This proposed method is compared with the previous control technique used in ECN for turbine fatigue load reduction to measure the overall efficiency of the proposed technique.

    Fatigue load has major effect on the turbine working age. In quantitative way, proposed LGQ design offers 8-10% approx. more fatigue load reduction in comparison with the previous design. In simple convention, decrease in turbine fatigue load increases the turbine age. This 8 - 10% fatigue load reduction offers 8 - 10% minimum increase in turbine working age which means that if a turbine works for 20 years in total for energy production, this proposed technique will add 2 extra years into the turbine working life. This age increase has major economic impact to make the wind turbine a viable alternative for energy production.

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