The Design Of Turbine Blade Of A Wind Power Generator Research Paper

The development of contemporary technologies opens wider opportunities for the introduction of innovations in the energy industry. In this regard, the focus on renewable sources of energy is particularly prospective because conventional sources of energy, such as oil and natural gas, are scarce resources. In addition, they have a negative environmental impact. This is why the development of alternative sources of energy emerges. In this regard, the use of wind power is particularly attractive for investors due to the availability of winds and existing technologies which allow generating electricity from the power of wind. Today, wind turbines comprise the core of the wind power industry because they are used for the generation of electricity. In this regard, features and technical characteristics of wind turbines determine, to a significant extent, the effectiveness of the generation of electricity from the wind power. In actuality, it is possible to distinguish different types of wind turbines which vary depending on their blades and overall construction. Therefore, the development of new technologies in the field of the construction of wind turbines and, especially turbine blades, is particularly important because it determines the overall effectiveness of wind turbines and productivity of wind power stations.

In actuality, researchers (Skamarock, et al., 2008) distinguish multiple technologies and different types of turbine blades used in the wind turbines. At the same time, they point out that the different type of blade is needed for the generation of electricity from the wind power based on different types of generation of electricity. According to differences in generation technology, wind turbines have been classified into four basic types: first, fixed-speed wind turbines; second, variable-slip wind turbines; third, doubly-fed induction generator (DFIG) wind turbines; full-converter wind turbines (Li, et al., 2004). The difference between types of generation of electricity requires considerable technological changes including the adaptation of the turbine blade to specific technical characteristics that the turbine should meet to maximize the effectiveness of its performance and increase the generation of electricity. 

One of the most widely-spread types of wind turbines is the fixed-speed wind turbine. Fixed-speed wind turbines (popularly known as the “Danish concept”) are the most basic utility scale wind turbines in operation. They operate with very little variation in turbine rotor speed and employ squirrel-cage induction machines directly connected to the grid. External reactive power support is necessary to compensate for the reactive power consumed by the induction machine. Because of the limited speed range in which these turbines operate, they are prone to torque spikes that may damage the mechanical subsystems within a turbine and cause transients in the electrical circuitry. These turbines may employ stall regulation, active stall regulation, or blade pitch regulation to regulate power at high wind speeds. Despite being relatively robust and reliable, there are significant disadvantages of this technology, namely that energy capture from the wind is suboptimal and reactive power compensation is required.

Another type of wind turbines includes variable-speed wind turbines (the broad category into which the other three dominant technologies fall) are designed to operate at a wide range of rotor speeds. These turbines usually employ blade pitching for power regulation. Speed and power controls allow these turbines to extract more energy from a given wind regime than fixed-speed turbines can. Variable-slip turbines employ wound-rotor induction machines that allow access to both the stator and the rotor of the machine. The rotor circuit of the machine is connected to an alternating current (AC)/direct current (DC) converter and a fixed resistance. The converter is switched to control the effective resistance in the rotor circuit of the machine to allow a wide range of operating slip (speed) variation (up to 10%). However, power is lost as heat in the external rotor circuit resistance. A controller may be employed to vary the effective external rotor resistance for optimal power extraction. Reactive power compensation is still required. Vestas OptiSlip turbines, such as the Vestas V66 (1.65 MW), were the most successful turbines to employ this technology. In fact, such turbines are quite productive, especially compared to fixed-speed wind turbines.

Furthermore, another type of DFIG turbines remedy the problem of power loss in the rotor circuit by employing a back-to back AC/DC/AC converter in the rotor circuit to recover the slip power. Flux-vector control of rotor currents allows decoupled real and reactive output power as well as maximized wind power extraction and lowered mechanical stresses. Also, these turbines usually employ blade pitching for power regulation. Because the converter handles only the power in the rotor circuit, it does not need to be rated at the machine’s full output power. The disadvantages of this technology — namely, higher cost and complexity — are offset by the ability to extract more energy from a given wind regime than the preceding technologies. The General Electric 1.5-MW turbine is an example of a successful DFIG implementation; more than 15,000 have been installed. In such a way, the development of DFIG turbines opens new prospects for the development of wind power industry. In this regard, it is worth mentioning the fact that DFIG turbines use different types of turbine blades compared to fixed-speed turbines and variable-speed turbines. DFIG turbines require the development of more complicated and technologically more advanced turbine blades that can maintain the higher efficiency of the turbine performance. 

Finally, there is one more type of wind turbines which use the most advanced turbine blades, which are full-converter turbines. In full-converter turbines, a back-to-back AC/DC/AC converter is the only power flow path from a wind turbine to the grid. Thus, there is no direct connection to the grid, and the converter has to be rated to handle the entire output power. These turbines usually employ high-pole-count, permanent magnet, synchronous generators to allow low-speed operation, thus allowing the elimination of the gearbox to increase reliability. Nonetheless, using induction generators is also possible (McNerney, et al., 1992). Also, full-converter turbines offer independent real and reactive power control, and they typically employ blade pitching for power regulation. A schematic for this technology is shown in Figure 4. Although these turbines are relatively expensive, the increased reliability and simplicity of the control scheme vis-à-vis DFIG turbines are attractive features, especially in offshore installations where maintenance is costly. Enercon manufactures turbines based on this technology, such as the popular E82 2-MW turbine.

The effectiveness of turbine blades is high. At this point, it is possible to refer to the case of HOMER turbine blades, which have proved their efficiency (See App.) the high level of this type of turbine blades, contribute to the effective performance of turbines due to the lighter weight and higher durability of such turbine blades. In addition, HOMER turbine blades have the advanced shape and they require the use of specific technologies that maximize their effectiveness (Nehrir, et al., 2000). In actuality, the effectiveness of their performance is high and HOMER is considered to be a highly advanced and successful design of turbine blades.

Thus, the development of new turbine blades and the improvement of their form and features contribute to the consistent improvement of the productivity of wind turbines and make them more efficient. Therefore, the focus on the development and improvement of turbine blades is one of the priorities in the development of the contemporary wind power industry and manufacturers of wind turbines invest substantial resources into the improvement of turbine blades.

References:

Ani, V. A. and A. N. Emetu, “Simulation and optimization of photovoltaic/diesel hybrid power generation system for health service facilities in rural environments,” Electronic Journal of Energy and Environment, vol. 1, no. 1, 2013

Li, P.; Banakar, H.; Keung, P-K.; Far, H.G.; Boon-Teck, O. (2004). “Macromodel of Spatial Smoothing in Wind Farms.” IEEE Transactions on Energy Conversion (22:1)

McNerney, G.; Richardson, R. (1992). “The Statistical Smoothing of Power Delivered to Utilities by Multiple Wind Turbines.” IEEE Transactions on Energy Conversion (7:4).

Nanahara, T.; Asari, M.; Sato, T.; Yamaguchi, K.; Shibata, M.; Maejima, T. (2004). “Smoothing Effects of Distributed Wind Turbines: Part 1—Coherence and Smoothing Effects at a Wind Farm.” Wind Energy (7:2).

Nehrir, M. H., B. J. LaMeres, G. Venkataramanan, V. Gerez, and L. A. Alvarado, (2000).  “An approach to evaluate the general performance of stand-alone wind/photovoltaic generating systems,” IEEE Transactions on Energy Conversion, vol. 15, no. 4, pp. 433–439

Skamarock, W.C.; Klemp, J.B.; Dudhia, J.; Gill, D.O.; Barker, D.M.; Duda, M.G.; Huang, X.Y.; Wang, W.; Powers, J.G. (2008). A Description of the Advanced Research WRF Version 3. NCAR Tech Notes-475+STR. Boulder, CO: National Center for Atmospheric Research

Appendix

Figure 1 Fixed –speed turbine

Figure 2 Variable slip wind turbine

Figure 3 DFIG wind turbine

Figure 4 Full-converter wind turbine

 Power consumption rating for HOMER
Power consumption Power 
(Watts) Qty Load
(watt qt) Vaccine refrigerator/freezer 60 1 60 Small refrigerator (nonmedical use) 300 1 300 Centrifuge 575 1 575 Hematology mixer 28 1 28 Microscope 15 1 15 Security light 10 4 40 Lighting 10 2 20 Sterilizer oven (laboratory autoclave) 1,564 1 1,564 Incubator 400 1 400 Water bath 1,000 1 1,000 Communication via VHF radio   1   Stand-by 2   2 Transmitting 30   30 Desktop computer 200 2 400 Printer 65 1 65

The electrical load (daily load demands) data for a health facility for HOMER.

Time Daily load demands Total/hr
1 2 3 4 5 6 7 8 9 10 11 12 13 14
0.00–0.59 60 40 400 2 502
1.00–1.59 60 40 400 2 502
2.00–2.59 60 40 400 2 502
3.00–3.59 60 40 400 2 502
4.00–4.59 60 40 400 2 502
5.00–5.59 60 40 400 2 502
6.00–6.59 60 400 2 462
7.00–7.59 60 400 2 462
8.00–8.59 60 400 2 462
9.00–9.59 60 15 20 400 2 30 400 65 992
10.00–10.59 60 300 28 15 20 400 2 30 400 1255
11.00–11.59 60 300 28 15 20 400 2 30 400 1255
12.00–12.59 60 300 575 15 20 1564 400 2 30 400 3366
13.00–13.59 60 300 575 15 20 400 2 400 65 1837
14.00–14.59 60 300 20 400 1000 2 65 1847
15.00–15.59 60 20 400 2 482
16.00–16.59 60 400 2 462
17.00–17.59 60 400 2 462
18.00–18.59 60 40 400 2 502
19.00–19.59 60 40 400 2 502
20.00–20.59 60 40 400 2 502
21.00–21.59 60 40 400 2 502
22.00–22.59 60 40 400 2 502
23.00–23.59 60 40 400 2 502
Total 1440 1500 1150 56 75 480 140 1564 9600 1000 48 120 2000 195 19368

1: Vaccine refrigerator/freezer, 2: Small refrigerator (nonmedical use), 3: Centrifuge, 4: Hematology mixer, 5: Microscope, 6: Security light, 7: Lighting, 8: Sterilizer oven (laboratory autoclave), 9: Incubator, 10: Water bath, 11: Communication via VHF radio stand-by, 12: Communication via VHF radio transmitting, 13: Desktop computer, 14: Printer.

HOMER Simulation results of the electricity production (kWh/yr), battery and inverter losses, and excess energy of the energy system configuration (PV/wind).
System operation PV/wind system Consumption kWh/yr % DC primary load 7,082 100 The total load to be supplied 7,082 100 Production kWh/yr % PV array 9,138 55 Wind turbine 7,490 45 Total energy generated 16,628 100 Losses kWh/yr Battery 460 Inverter 1,250 Total losses 1,710 Excess energy going to dump load 7,836 Total energy supplied to the load 7,082

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"The terms offer and acceptance." freeessays.club, 17 May 2016

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"The terms offer and acceptance." freeessays.club, 17 May 2016

[Accessed: February 4, 2023]

"The terms offer and acceptance." freeessays.club, 17 May 2016

[Accessed: February 4, 2023]

"The terms offer and acceptance." freeessays.club, 17 May 2016

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