Journal of Wind Energy The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. Power Quality Investigation of Distribution Networks Embedded Wind Turbines Tue, 12 Apr 2016 11:30:16 +0000 In recent years a multitude of events have created a new environment for the electric power infrastructure. The presence of small-scale generation near load spots is becoming common especially with the advent of renewable energy sources such as wind power energy. This type of generation is known as distributed generation (DG). The expansion of the distributed generators- (DGs-) based wind energy raises constraints on the distribution networks operation and power quality issues: voltage sag, voltage swell, voltage interruption, harmonic contents, flickering, frequency deviation, unbalance, and so forth. Consequently, the public distribution network conception and connection studies evolve in order to keep the distribution system operating in optimal conditions. In this paper, a comprehensive power quality investigation of a distribution system with embedded wind turbines has been carried out. This investigation is carried out in a comparison aspect between the conventional synchronous generators, as DGs are widely in use at present, and the different wind turbines technologies, which represent the foresightedness of the DGs. The obtained results are discussed with the IEC 61400-21 standard for testing and assessing power quality characteristics of grid-connected wind energy and the IEEE 1547-2003 standard for interconnecting distributed resources with electric power systems. A. Elsherif, T. Fetouh, and H. Shaaban Copyright © 2016 A. Elsherif et al. All rights reserved. Long-Term Wind Characteristics at Selected Locations in Mauritius for Power Generation Thu, 29 Oct 2015 08:39:50 +0000 Interests in wind energy have gained impetus in many developed and developing countries worldwide during the last three decades. This is due to awareness of the population about the depletion of fossil fuels as well as Government campaigns and initiatives to encourage the use of renewable sources of energy. This work focuses on the wind energy potential at two selected locations (Plaisance and Vacoas) in Mauritius. The emphasis is to assess whether small-wind turbines have a potential in these regions for generation of power for domestic applications. Such wind turbines can range in size from 400 W to 10 kW depending on the amount of electricity to be generated. The assessment is based on the correlation of the local wind speed data to a two-parameter Weibull probability distribution in order to effectively estimate the average wind power density of the sites. Nearly 40 years of mean wind speed data is utilized. Of the two sites investigated it is found that Plaisance yielded the highest wind velocity (as compared to Vacoas). The study also estimates the energy output of six commercial small-wind turbines of capacity ranging from 1 kW to 3 kW at these two sites, placed at multiple heights. A. Z. Dhunny, M. R. Lollchund, and S. D. D. V. Rughooputh Copyright © 2015 A. Z. Dhunny et al. All rights reserved. MPPT of Magnus Wind System with DC Servo Drive for the Cylinders and Boost Converter Tue, 18 Aug 2015 14:17:01 +0000 This paper presents an algorithm MPPT (Maximum Power Point Tracking) for a Magnus wind system with a DC servo drive system (DC drive and BLDC motor) to rotate the turbine cylinders. The optimal cylinders rotation is the one to deliver the maximum power extracted from the wind tracked by fixed and adaptive step HCC (Hill Climbing Control) acting on the servo drive. The proposed wind system consists of a PMSG (Permanent Magnet Synchronous Generator), a three-phase diode rectifier, a DC/DC (boost) converter, and a resistive load. Furthermore, the boost converter acts with the fixed step HCC algorithm to track the maximum power operating point. Therefore, the MPPT for a Magnus wind system requires both tracking for the optimal cylinder speed and the optimal generator speed. Maro Jinbo, Felix Alberto Farret, Ghendy Cardoso Junior, Daniel Senter, and Marcelo Franklin Lorensetti Copyright © 2015 Maro Jinbo et al. All rights reserved. Separated Pitch Control at Tip: Innovative Blade Design Explorations for Large MW Wind Turbine Blades Tue, 24 Feb 2015 13:02:14 +0000 This paper focuses on the deployment and evaluation of a separated pitch control at blade tip (SePCaT) control strategy for large megawatt (MW) wind turbine blade and explorations of innovative blade designs as a result of such deployment. SePCaT configurations varied from five to thirty percent of the blade length in 5 percentage increments (SePCaT5, SePCaT10, SePCaT15, SePCaT20, SePCaT25, and SePCaT30) are evaluated by comparing them to aerodynamical responses of the traditional blade. For low, moderate, high, and extreme wind speed variations treated as 10, 20, 30, and 40 percent of reference wind speeds, rotor power abatement in region 3 of the wind speed power curve is realized by feathering full length blade by 6, 9, 12, and 14 degrees, respectively. Feathering SePCaT30, SePCaT25, SePCaT20, and SePCaT15 by 14, 16, 26, and 30 degrees, respectively, achieves the same power abatement results when compared to traditional blade at low wind speeds. Feathering SePCaT30, SePCaT25, and SePCaT20 by 18, 26, and 30 degrees on the other hand has the same effect at high wind speeds. SePCaT30 feathered to 26 and 30 degrees has the same abatement effects when compared to traditional blade at high and extreme wind speeds. Ranjeet Agarwala and Paul I. Ro Copyright © 2015 Ranjeet Agarwala and Paul I. Ro. All rights reserved. Load Sharing of Wind Based Microgrid in Autonomous Operation Tue, 30 Dec 2014 09:10:59 +0000 Autonomous wind energy conversion systems sharing a common load consist of a number of voltage source converters operating in parallel. A suitable control system should ensure desired load sharing among these as a number of these sources operating in parallel are required to meet the load demand and load excursions should not lead to instability of the system. In absence of the grid there is no reference angle for synchronization. Hence, a control scheme for parallel-connected three-phase converters incorporating the desirable features needs to be developed in order to exploit the renewable energy sources, which are intermittent in nature as effectively as possible in case of an autonomous microgrid. A simple and effective droop control strategy without the use of conventional αβ technique incorporating only dq components has been proposed for load sharing among wind energy conversion systems connected by back to back voltage source converters in autonomous operation. The need for communication link should also be avoided, hence reducing the system cost. The system is modelled using Matlab and the control is authenticated by simulation results. Aarti Gupta, Dinesh Kumar Jain, and Surender Dahiya Copyright © 2014 Aarti Gupta et al. All rights reserved. Comparative Assessment of SVC and TCSC Controllers on the Small Signal Stability Margin of a Power System Incorporating Intermittent Wind Power Generation Thu, 11 Dec 2014 10:43:05 +0000 Wind power is highly variable due to the stochastic behavior of wind speeds. This intermittent nature could excite the electromechanical modes resulting in the small signal instability of a power system. In this study, the performance of static VAR compensation (SVC) and thyristor controlled series capacitor (TCSC) controllers in the damping of electromechanical modes is analyzed and compared. The study employs probabilistic modal analysis method using Monte Carlo simulation and Latin hypercube sampling techniques. Various scenarios are created to get insight into the study. The results obtained from the modal analysis are verified by using the time-domain simulation. Some of the key results show that SVC is more robust in the damping of electromechanical modes compared to TCSC. The result also reveals that allocation of power system stabilizer (PSS) using probabilistic method is more effective and robust compared to deterministic approach. T. R. Ayodele Copyright © 2014 T. R. Ayodele. All rights reserved. Control of Variable Speed Variable Pitch Wind Turbine at Above and Below Rated Wind Speed Wed, 22 Oct 2014 09:13:04 +0000 The paper presents a nonlinear approach to wind turbine (WT) using two-mass model. The main aim of the controller in the WT is to maximize the energy output at varying wind speed. In this work, a combination of linear and nonlinear controllers is adapted to variable speed variable pitch wind turbines (VSVPWT) system. The major operating regions of the WT are below (region 2) and above rated (region 3) wind speed. In these regions, generator torque control (region 2) and pitch control (region 3) are used. The controllers in WT are tested for below and above rated wind speed for step and vertical wind speed profile. The performances of the controllers are analyzed with nonlinear FAST (Fatigue, Aerodynamics, Structures, and Turbulence) WT dynamic simulation. In this paper, two nonlinear controllers, that is, sliding mode control (SMC) and integral sliding mode control (ISMC), have been applied for region 2, whereas for pitch control in region 3 conventional PI control is used. In ISMC, the sliding manifold makes use of an integral action to show effective qualities of control in terms of the control level reduction and sliding mode switching control minimization. Saravanakumar Rajendran and Debashisha Jena Copyright © 2014 Saravanakumar Rajendran and Debashisha Jena. All rights reserved. Combining Wind and Pumped Hydro Energy Storage for Renewable Energy Generation in Ireland Thu, 21 Aug 2014 06:01:44 +0000 Ireland has one of the highest wind energy potentials in Europe. The intermittent nature of wind makes this renewable resource impractical as a sole source of energy. Combining wind energy with pumped hydro energy storage (PHES) can overcome this intermittency, consuming energy during low-demand periods and supplying energy for periods of high demand. Currently Ireland has a number of hydroelectric power plants and wind farms of various scales in operation. A feasibility study was conducted to investigate the potential of securing a reliable source of renewable energy by increasing the penetration of hydroelectric power by means of combined wind-PHES developments. The greatest wind potential is experienced along the western coast of Ireland and a number of sites were identified here which satisfied a minimum mean wind speed criterion of 10.5 ms−1. Each site was then further evaluated according to topographical requirements for PHES. All but two of the identified sites are immediately unsuitable due to the presence of areas protected under European legislation; this highlights the nonenergy related obstacles in the path of renewable energy generation in Ireland and suggests that a compromise should be researched which could facilitate both renewable energy generation and species and habitat protection in Europe. Alice Coburn, Eilín Walsh, Patrick J. Solan, and Kevin P. McDonnell Copyright © 2014 Alice Coburn et al. All rights reserved. A New Hybrid Forecasting Strategy Applied to Mean Hourly Wind Speed Time Series Thu, 12 Jun 2014 00:00:00 +0000 An alternative electric power source, such as wind power, has to be both reliable and autonomous. An accurate wind speed forecasting method plays the key role in achieving the aforementioned properties and also is a valuable tool in overcoming a variety of economic and technical problems connected to wind power production. The method proposed is based on the reformulation of the problem in the standard state space form and on implementing a bank of Kalman filters (KF), each fitting an ARMA model of different order. The proposed method is to be applied to a greenhouse unit which incorporates an automatized use of renewable energy sources including wind speed power. Stylianos Sp. Pappas, Dimitrios Ch. Karamousantas, George E. Chatzarakis, and Christos Sp. Pappas Copyright © 2014 Stylianos Sp. Pappas et al. All rights reserved. Observation of the Starting and Low Speed Behavior of Small Horizontal Axis Wind Turbine Thu, 05 Jun 2014 08:48:51 +0000 This paper describes the starting behavior of small horizontal axis wind turbines at high angles of attack and low Reynolds number. The unfavorable relative wind direction during the starting time leads to low starting torque and more idling time. Wind turbine models of sizes less than 5 meters were simulated at wind speed range of 2 m/s to 5 m/s. Wind turbines were modeled in Pro/E and based on the optimized designs given by MATLAB codes. Wind turbine models were simulated in ADAMS for improving the starting behavior. The models with high starting torques and less idling times were selected. The starting behavior was successfully improved and the optimized wind turbine models were able to produce more starting torque even at wind speeds less than 5 m/s. Sikandar Khan, Kamran Shah, Izhar-Ul-Haq, Hamid Khan, Sajid Ali, Naveed Ahmad, Muhammad Abid, Haider Ali, Ihsanullah, and Mazhar Sher Copyright © 2014 Sikandar Khan et al. All rights reserved. On the Deflexion of Anisotropic Structural Composite Aerodynamic Components Mon, 20 Jan 2014 13:57:19 +0000 This paper presents closed form solutions to the classical beam elasticity differential equation in order to effectively model the displacement of standard aerodynamic geometries used throughout a number of industries. The models assume that the components are constructed from in-plane generally anisotropic (though shown to be quasi-isotropic) composite materials. Exact solutions for the displacement and strains for elliptical and FX66-S-196 and NACA 63-621 aerofoil approximations thin wall composite material shell structures, with and without a stiffening rib (shear-web), are presented for the first time. Each of the models developed is rigorously validated via numerical (Runge-Kutta) solutions of an identical differential equation used to derive the analytical models presented. The resulting calculated displacement and material strain fields are shown to be in excellent agreement with simulations using the ANSYS and CATIA commercial finite element (FE) codes as well as experimental data evident in the literature. One major implication of the theoretical treatment is that these solutions can now be used in design codes to limit the required displacement and strains in similar components used in the aerospace and most notably renewable energy sectors. J. Whitty, T. Haydock, B. Johnson, and J. Howe Copyright © 2014 J. Whitty et al. All rights reserved. Influences of Wind Energy Integration into the Distribution Network Mon, 11 Nov 2013 13:42:41 +0000 Wind energy is one of the most promising renewable energy sources due to its availability and climate-friendly attributes. Large-scale integration of wind energy sources creates potential technical challenges due to the intermittent nature that needs to be investigated and mitigated as part of developing a sustainable power system for the future. Therefore, this study developed simulation models to investigate the potential challenges, in particular voltage fluctuations, zone substation, and distribution transformer loading, power flow characteristics, and harmonic emissions with the integration of wind energy into both the high voltage (HV) and low voltage (LV) distribution network (DN). From model analysis, it has been clearly indicated that influences of these problems increase with the increased integration of wind energy into both the high voltage and low voltage distribution network; however, the level of adverse impacts is higher in the LV DN compared to the HV DN. G. M. Shafiullah, Amanullah M. T. Oo, A. B. M. Shawkat Ali, and Alex Stojcevski Copyright © 2013 G. M. Shafiullah et al. All rights reserved. Electric Control Substituting Pitch Control for Large Wind Turbines Wed, 18 Sep 2013 11:58:52 +0000 A completely electrical control of a variable speed wind turbine is experimentally verified. A vertical axis wind turbine with a direct driven generator and an electrical system with diode rectification and full inverter connected to the electric grid is presented. This is the first paper that presents this novel 200 kW wind power plant erected at the west coast of Sweden. The turbine has fixed pitch and is only controlled electrically accommodated by passive stall of the blades. By electrically controlling the generator rotational speed with the inverter, passive stall regulation is enabled. The first results on experimental verification of stall regulation in gusty wind speeds are presented. The experiments show that the control system can keep the turbine rotational speed constant even at very gusty winds. It is concluded that electrical control accommodated by passive stall is sufficient as control of the wind turbine even at high wind speeds and can substitute mechanical control such as blade pitch. Jon Kjellin, Sandra Eriksson, and Hans Bernhoff Copyright © 2013 Jon Kjellin et al. All rights reserved. Prospects of Wind-Diesel Generator-Battery Hybrid Power System: A Feasibility Study in Algeria Mon, 26 Aug 2013 13:11:34 +0000 The present work analyses the feasibility of a wind-diesel generator-battery hybrid system. The wind energy resource data are collected from the weather station at the Renewable Energy Development Center of Bouzareah in Algeria. The recorded values vary from 5.5 m/s to 7 m/s at 25 m. The hybrid system analysis has shown that for a household consuming 1,270 kWh/yr, the cost of energy is 1.205 USD/kWh and produces 2,493 kWh/yr in which 93% of electricity comes from wind energy. From this study, it is clear that the optimized hybrid system is more cost effective compared to the diesel generator system alone where the NPC and COE are equal, respectively, to 19,561 USD and 1.205 USD/kWh and 47,932 USD and 2.952 USD/kWh. The sensitivity analysis predicts that the grid extension distance varies from 1.25 to 1.85 km depending on wind speed and fuel price which indicate a positive result to implement a stand-alone hybrid power system as an alternative to grid extension. In addition to the feasibility of this system, it can reduce the emission of the CO2, SO2, and NOx, respectively, from 4758 to 147, from 9.45 to 0.294, and from 105 to 3.23 kg/yr. Investments in autonomous renewable energy systems should be considered particularly in remote areas. They can be financed in the framework of the National Energy Action Plan of Algeria. Djohra Saheb-Koussa, Mustapha Koussa, and Nourredine Said Copyright © 2013 Djohra Saheb-Koussa et al. All rights reserved. Power Generation Expansion Planning Including Large Scale Wind Integration: A Case Study of Oman Wed, 17 Jul 2013 10:27:05 +0000 Many options can be effectively used to meet the future power needs of a country in ways which would be more economically viable, environmentally sound, and socially just. A least-cost generation expansion planning study is conducted to find the economic feasibility of large scale integration of wind farms in the main interconnected transmission system of Oman. The generation expansion planning software used is WASP which is restricted in its ability to model intermittent nature of wind. Therefore, a wind turbine is modeled as a thermal plant with high forced outage rate related to its capacity factor. The result of the study has shown that wind turbines are economically viable option in the overall least-cost generation expansion plan for the Main Interconnected System of Oman. Arif S. Malik and Cornelius Kuba Copyright © 2013 Arif S. Malik and Cornelius Kuba. All rights reserved. Statistical and Spectral Analysis of Wind Characteristics Relevant to Wind Energy Assessment Using Tower Measurements in Complex Terrain Wed, 10 Jul 2013 11:11:13 +0000 The main objective of the study was to investigate spatial and temporal characteristics of the wind speed and direction in complex terrain that are relevant to wind energy assessment and development, as well as to wind energy system operation, management, and grid integration. Wind data from five tall meteorological towers located in Western Nevada, USA, operated from August 2003 to March 2008, used in the analysis. The multiannual average wind speeds did not show significant increased trend with increasing elevation, while the turbulence intensity slowly decreased with an increase were the average wind speed. The wind speed and direction were modeled using the Weibull and the von Mises distribution functions. The correlations show a strong coherence between the wind speed and direction with slowly decreasing amplitude of the multiday periodicity with increasing lag periods. The spectral analysis shows significant annual periodicity with similar characteristics at all locations. The relatively high correlations between the towers and small range of the computed turbulence intensity indicate that wind variability is dominated by the regional synoptic processes. Knowledge and information about daily, seasonal, and annual wind periodicities are very important for wind energy resource assessment, wind power plant operation, management, and grid integration. Radian Belu and Darko Koracin Copyright © 2013 Radian Belu and Darko Koracin. All rights reserved.