scholarly journals An Experimental Investigation of Wake Characteristics and Power Generation Efficiency of a Small Wind Turbine under Different Tip Speed Ratios

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2113 ◽  
Author(s):  
Yu-Ting Wu ◽  
Chang-Yu Lin ◽  
Che-Ming Hsu
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Power Output ◽  
Estimation Method ◽  
Mechanical Power ◽  
Power Coefficient ◽  
Regulation System ◽  
Generation Efficiency ◽  
Blade Rotation ◽  
Wake Characteristics

We carried out a wind tunnel experiment to examine the power generation efficiency of a stand-alone miniature wind turbine and its wake characteristics at different tip speed ratios (TSRs) under the same mean inflow velocity. Resistors in the electrical circuit were adjusted to control the TSRs to 0.9, 1.5, 3.0, 4.1, 5.2, and 5.9. The currents were measured to estimate the turbine power outputs versus the TSRs and then establish the actual power generation coefficient Cp distribution. To calculate the mechanical power coefficient, a new estimation method of the mechanical torque constant is proposed. A reverse calibration on the blade rotation speed was performed with given electrical voltages and currents that are used to estimate the mechanical power coefficient Cp, mech. In the experiment, the maximum Cp,mech was approximately 0.358 (corresponding to the maximum Cp of 0.212) at the TSR of 4.1. Significant findings indicate that the turbine at the TSR of 5.2 produces a smaller torque but a larger power output compared with that at the TSR of 3.0. This comparison further displays that the turbine at the TSR of 5.2, even with larger power output, still produces a turbine wake that has smaller velocity deficits and smaller turbulence intensity than that at the TSR of 3.0. This behavior demonstrates the significance of the blade-rotation control (i.e., pitch regulation) system to the turbine operation in a large wind farm for raising the overall farm power productivity.

scholarly journals Numerical simulation and experimental study of blade pitch effect on Darrieus straight-bladed wind turbine with high solidity: A case study under realistic conditions

2020 ◽  
Author(s):  
Milad Babadi Soultanzadeh ◽  
Alireza Moradi
Keyword(s):  
Wind Turbine ◽  
Numerical Method ◽  
Pitch Angle ◽  
Numerical Results ◽  
Power Coefficient ◽  
Speed Ratio ◽  
Regulation System ◽  
Lower Velocity ◽  
Realistic Condition ◽  
Tip Speed Ratio

Abstract Numerical and experimental studies were performed to examined the influence of pitch angle on the aerodynamic performance of a small Darrieus straight blade vertical axis wind turbine with high solidity and pitch regulation system under a realistic condition. By comparing experimental and numerical results, numerical results were validated. The power coefficient was measured and calculated at different tip speed ratios and for two pitch angles 0 and 5. The results revealed that 5 degrees increase in the pitch angle led to 25% elevation in the maximum value of the power coefficient (performance coefficient). Also, the numerical results showed higher accuracy at lower tip speed ratios for both pitch angles. After numerical method validation, numerical method employed to calculate the coefficient of performance and coefficient of torque function of Azimuth position as well as the flow field in the rotor affected zone and lateral distance. According to the numerical results, vorticity generation increased by the rise in the pitch angle at a constant tip speed ratio; the maximum performance coefficient occurred at a lower tip speed ratio with elevation in the pitch angle; finally, the increment in the pitch angle led to lower velocity profile in lateral distances of the rotor.

Comparison of Various Blade Profiles in a Two-Blade Conventional Savonius Wind Turbine

2020 ◽  
Vol 143 (2) ◽  
Author(s):  
Rahim Hassanzadeh ◽  
Milad Mohammadnejad ◽  
Sajad Mostafavi
Keyword(s):  
Wind Speed ◽  
Wind Turbine ◽  
Power Output ◽  
Urban Areas ◽  
Cost Effective ◽  
Maximum Power ◽  
Power Coefficient ◽  
Total Power ◽  
Wind Speeds ◽  
Savonius Wind Turbine

Abstract Savonius turbines are one of the old and cost-effective turbines which extract the wind energy by the drag force. Nowadays, they use in urban areas to generate electricity due to their simple structure, ease of maintenance, and acceptable power output under a low wind speed. However, their efficiency is low and the improvement of their performance is necessary to increase the total power output. This paper compares four various blade profiles in a two-blade conventional Savonius wind turbine. The ratios of blade diameter to the blade depth of s/d = 0.3, 0.5, 0.7, and 1 are tested under different free-wind speeds of 3, 5, and 7 m/s and tip speed ratios (TSRs) in the range from 0.2 to 1.2. It is found that the profile of blades in a Savonius rotor plays a considerable role in power characteristics. Also, regardless of blades profile and free-wind speed, the maximum power coefficient develops in TSR = 0.8. In addition, increasing the free-wind speed enhances the rotor performance of all cases under consideration. Finally, it is revealed that the rotor with s/d = 0.5 provides maximum power coefficients in all free-wind speeds and TSR values among the rotors under consideration, whereas the rotor with s/d = 1 is the worth cases.

Study of the Energy Consumption Characteristic of a 1000MW Ultra-Supercritical Unit

2013 ◽  
Vol 860-863 ◽  
pp. 629-633
Author(s):  
Feng Ping Pan ◽  
Shi He Chen ◽  
Ya Qing Zhu ◽  
Zhi Qiang Pang ◽  
Shu Mei Wu ◽  
...  
Keyword(s):  
Power Generation ◽  
High Pressure ◽  
Energy Consumption ◽  
Temperature Control ◽  
Power Output ◽  
Superheated Steam ◽  
Unit Operation ◽  
Steam Temperature ◽  
Generation Efficiency ◽  
Superheated Steam Temperature

A 1000MW ultra-supercritical unit was studied to gain the energy consumption characteristics by means of thermodynamic analysis. Comparing with the designed conditions, the power generation efficiency under real operation is much less; especially under 50% and 100% rated loads. The higher superheated steam temperature and lower reheat temperature were found to explain that. At the real running, the higher superheated steam temperature induced more attemperation water, while reheat temperature lower than the designed point would decrease the power output. Aiming at solving issues about temperature control in unit operation, several details could be paid extra attention to. For instance, attemperating water comes from outlet of the high-pressure heaters would have a much slighter influence on generating efficiency.

scholarly journals Development of Flapping Panel Vertical Axis Wind Turbine

2019 ◽  
Vol 9 (1) ◽  
pp. 2119-2122
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Power Output ◽  
Renewable Energy Sources ◽  
Electrical Energy ◽  
Vertical Axis ◽  
Vertical Axis Wind Turbine ◽  
Considerable Part ◽  
Ansys Fluent ◽  
Generation Capacity

In a developing nation like India, electricity has become one of the most important basic needs nowadays. Coal and gasoline based power generation capacity stands at 71% in India, which contributes to a considerable part of air pollution. There are various renewable energy sources which are pollution free, one among them is the wind energy. So the main objective of the project is to facilitate pollution free power generation for individual purpose. In order to understand the problem and working, a flapping panel vertical axis wind turbine was designed. The main advantage of using a vertical axis wind turbine is that it need not pointed towards the wind and also vertical axis wind turbine is more comfortable to erect for domestic purposes. The flapping panel wind turbine is designed using solidworks software and analysed using Ansys Fluent. By making use of the wind, the flapping panels attached to the shaft rotate and the rotor is connected to the permanent magnet electricity generator (PMG). The PMG converts the Kinetic energy of the rotor shaft into electrical energy. The PMG we have used has the capacity of producing maximum power at 1200rpm. On calculating theoretically, the power output is found to be 8W for the rotation of 76.39 rpm and for 1200rpm the power output is calculated to be 125W. The entire wind turbine setup is compact in size and can be easily mounted and erected.

scholarly journals Optimum Power Output Control of a Wind Turbine Rotor

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
S. Wijewardana ◽  
M. H. Shaheed ◽  
R. Vepa
Keyword(s):  
Equilibrium Point ◽  
Wind Turbine ◽  
Power Output ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
Power Coefficient ◽  
Output Control ◽  
The Stability ◽  
Lift And Drag ◽  
Wind Turbine Rotor

An active and optimum controller is applied to regulate the power output from a wind turbine rotor. The controller is synthesized in two steps. The first step defines the equilibrium operation point and ensures that the desired equilibrium point is stable. The stability of the equilibrium point is guaranteed by a control law that is synthesized by applying the methodology of model predictive control (MPC). The method of controlling the turbine involves pitching the turbine blades. In the second step the blade pitch angle demand is defined. This involves minimizing the mean square error between the actual and desired power coefficient. The actual power coefficient of the wind turbine rotor is evaluated assuming that the blade is capable of stalling, using blade element momentum theory. This ensures that the power output of the rotor can be reduced to any desired value which is generally not possible unless a nonlinear stall model is introduced to evaluate the blade profile coefficients of lift and drag. The relatively simple and systematic nonlinear modelling and MPC controller synthesis approach adopted in this paper clearly highlights the main features on the controller that is capable of regulating the power output of the wind turbine rotor.

Integrated Overtopping Wave Energy Converter in a Hybrid Offshore Wind Turbine Power Generation System

2014 ◽  
Author(s):  
Artemis Ioannou ◽  
Anestis I. Kalfas ◽  
Theofanis V. Karambas
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Power Output ◽  
Fossil Fuel ◽  
Integrated Design ◽  
Offshore Wind ◽  
Offshore Wind Turbine ◽  
Generation System ◽  
Micro Gas Turbine ◽  
Generation Unit

Marine construction technologies could be designed to offer power generation in addition to their sea defence and coastal erosion prevention function. This paper aims to evaluate and optimize the performance of an Overtopping Wave Energy Converter (OWEC) as part of a hybrid generation system integrated into an offshore wind turbine. For that purpose, two configurations have been investigated. A 100kW OWEC was combined with a micro-gas turbine of 80kW at the first configuration and the same OWEC with a wind turbine (WT) of 200kW at the second. The preliminary design of an integrated offshore OWEC/WT is presented. The findings of the present investigation have been applied to a specific test case of a small, off–grid island, in the Aegean archipelago. Regarding its power requirement, Donoussa island currently relies exclusively on fossil fuel. At the same time, a high wave and wind power potential is available. A representative set of wind data have been obtained and numerically analyzed. A wave simulation, overtopping prediction and power output has been carried out. Moreover, a techno-economic and environmental assessment of the proposed offshore integrated design is presented. The stand alone coastal OWEC, and a single offshore wind turbine have been evaluated versus the proposed offshore hybrid power generation scheme. The OWEC is expected to generate 320MWh per year, thus covering half of the island’s estimated power demand. Using both wave and wind power generation, energy autonomy of the island could be achieved. In order to cover the requirements of extreme cases, a micro gas-turbine power generation unit has been considered, in parallel to the existing fossil fuel power generation unit. From the techno-economic assessment point of view, the coastal OWEC construction has a shorter return on investment time of 11 years as compared to 13 years of the proposed integrated design but lower profitable investment. Besides providing sufficient electrical power for the island, the additional environmental benefit of the proposed system is that it can be used to counter coastal erosion. The integrated offshore OWEC/WT design could potentially double the power output of each and every offshore wind turbine installation. This result could therefore be interpreted either as halving of the required number of offshore wind turbines erections or as doubling of the power output of an offshore wind park.

Variable Speed Direct Drive Wind Controller for a Rim Driven Wind Turbine

2012 ◽  
Author(s):  
Chase Hubbard ◽  
Rob Hovsapian ◽  
Srinivas Kosaraju
Keyword(s):  
Power Generation ◽  
Control System ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Aerodynamic Force ◽  
Rotor Blades ◽  
Power Coefficient ◽  
Variable Speed ◽  
Direct Drive ◽  
Significant Difference

Multi-blade shaft driven wind turbines depend greatly on the angle of attack as an important factor that the control system monitors such that a maximum amount of aerodynamic force is seen by the rotor blades. This is one significant difference when controlling a Rim Driven Wind Turbine (RDWT). The controller for a RDWT is required to simply point the tower such that it is facing the wind for maximum power generation. This is achieved by incorporating a Variable Speed Direct Drive (VSDD) wind operation control system to control the power production and safe operation of the RDWT. Another consideration for the control system is its integration with the generator. Since the power generation is rim driven, thus operating at a higher variable speed. With information related to the wind turbine’s diameter and the wind speed at any given time it can be calculated how much power can be potentially generated. This can then be in turn relayed to the generator from the wind turbine controller. This information can be relayed using controller-controller communication (such as an analog voltage signal or protocol based communication such as MODBUS RTU or TCP/IP) representing the power coefficient from Betz’ Law. A feasibly controllable system implements a signal from the overall wind turbine controller that in turn supplies the generator with how much power is available in the system to maximize power generation for a broad range of traditionally unrealizable wind conditions (3 m/s to 30 m/s). Rim Driven Wind Turbines represent an evolution in fundamental design of how the wind can be harnessed for power. This paper will discuss the VSDD’s unique design and aspects of maintaining controllability thorough out the overall system operation.

Improvement in Solar Chimney Power Generation by Using a Diffuser Tower

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Shinsuke Okada ◽  
Takanori Uchida ◽  
Takashi Karasudani ◽  
Yuji Ohya
Keyword(s):  
Power Generation ◽  
Wind Turbine ◽  
Static Pressure ◽  
Solar Chimney ◽  
Generation Efficiency ◽  
High Rise ◽  
Pressure Region ◽  
Computational Fluid Dynamics Cfd ◽  
Inner Diameter ◽  
Power Generation Systems

The solar chimney prototype, operated in Spain from 1982 to 1989, verified the concept of the solar chimney. The power generation mechanism in this system is to turn the wind turbine placed inside a high rise cylindrical hollow tower by an induced thermal updraft. As long as the thermal updraft is induced inside the tower by the solar radiation, this system can produce electricity. The disadvantage of this system is the low power generation efficiency compared to other solar energy power generation systems. To overcome this disadvantage, we improved the mechanism in order to augment the velocity of the air which flows into the wind turbine. By applying a diffuser tower instead of a cylindrical one, the efficiency of the systems power generation is increased. The mechanism that we investigated was the effect of the diffuser on the solar chimney structure. The inner diameter of the tower expands as the height increases so that the static pressure recovery effect of the diffuser causes a low static pressure region to form at the bottom of the tower. This effect induces greater airflow within the tower. The laboratory experiment, as does the computational fluid dynamics (CFD) analysis of the laboratory sized model, shows that the proposed diffuser type tower induces a velocity approximately 1.38–1.44 times greater than the conventional cylindrical type. The wind power generation output is proportional to the cube of the incoming wind velocity into the wind turbine; therefore, approximately 2.6–3.0 times greater power output can be expected from using the diffuser type tower.

scholarly journals Evaluation of Photovoltaic Power Generation by using Deep Learning in Solar Panels Installed in Buildings

Energies ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 3564 ◽  
Author(s):  
Wei
Keyword(s):  
Neural Network ◽  
Power Generation ◽  
Deep Learning ◽  
Power Output ◽  
Solar Panel ◽  
Second Phase ◽  
Solar Panels ◽  
Generation Efficiency ◽  
Southern Taiwan ◽  
Pv Power Generation

Southern Taiwan has excellent solar energy resources that remain largely unused. This study incorporated a measure that aids in providing simple and effective power generation efficiency assessments of solar panel brands in the planning stage of installing these panels on roofs. The proposed methodology can be applied to evaluate photovoltaic (PV) power generation panels installed on building rooftops in Southern Taiwan. In the first phase, this study selected panels of the BP3 series, including BP350, BP365, BP380, and BP3125, to assess their PV output efficiency. BP Solar is a manufacturer and installer of photovoltaic solar cells. This study first derived ideal PV power generation and then determined the suitable tilt angle for the PV panels leading to direct sunlight that could be acquired to increase power output by panels installed on building rooftops. The potential annual power outputs for these solar panels were calculated. Climate data of 2016 were used to estimate the annual solar power output of the BP3 series per unit area. The results indicated that BP380 was the most efficient model for power generation (183.5 KWh/m2-y), followed by BP3125 (182.2 KWh/m2-y); by contrast, BP350 was the least efficient (164.2 KWh/m2-y). In the second phase, to simulate meteorological uncertainty during hourly PV power generation, a surface solar radiation prediction model was developed. This study used a deep learning–based deep neural network (DNN) for predicting hourly irradiation. The simulation results of the DNN were compared with those of a backpropagation neural network (BPN) and a linear regression (LR) model. In the final phase, the panel of module BP3125 was used as an example and demonstrated the hourly PV power output prediction at different lead times on a solar panel. The results demonstrated that the proposed method is useful for evaluating the power generation efficiency of the solar panels.

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