Turbulence influence on wind energy extraction for a medium size vertical axis wind turbine

Abstract

The relation between power performance and turbulence intensity for a VAWT H-rotor is studied using logged data from a 14 month (discontinuous) period with the H-rotor operating in wind speeds up to 9 m/s. The turbine, designed originally for a nominal power of 200 kW, operated during this period mostly in a restricted mode due to mechanical concerns, reaching power levels up to about 80 kW. Two different approaches are used for presenting results, one that can be compared to power curves consistent with the International Electrotechnical Commission (IEC) standard and one that allows isolating the effect of turbulence from the cubic variation of power with wind speed. Accounting for this effect, the turbine still shows slightly higher efficiency at higher turbulence, proposing that the H-rotor is well suited for wind sites with turbulent winds. The operational data are also used to create a C p (λ) curve, showing slightly lower C p compared with a curve simulated by a double multiple streamtube model.

Performance and wake comparison of horizontal and vertical axis wind turbines under varying surface roughness conditions

“…In the case of the VAWT, a minor influence of the surface condition in the obtained C P is noticed. Similar results were obtained in the experimental work of Möllerström et al, which showed a slightly higher efficiency of a VAWT at higher turbulence, proposing that the H‐rotor is appropriate for wind sites with turbulent winds.…”

Noise Emission of a 200 kW Vertical Axis Wind Turbine

“…Only one 200 kW turbine was ever built by vertical wind AB, making the T1-turbine unique. The turbine, which is located at Thorsholm (56°56ʹ29ʺN, 12°30ʹ38ʺE) just outside of Falkenberg at the west coast of Sweden, is today owned by Uppsala University and it is the subject of research in a variety of fields [20][21][22][23]. The T1-turbine has a direct drive permanent magnet synchronous generator mounted at the bottom of the tower and connected to the rotor by a steel shaft.…”

Location of aerodynamic noise sources from a 200 kW vertical-axis wind turbine

“…For the full-Darrieus turbine, the blade works in the stall region for parts of the cross-section area, decreasing the contribution from these parts. Since the power coefficient of the T1 turbine is measured to peak at about C p ¼0.33 [41], we may assume a power-coefficient loss of Δ = C 0.07 p due to the presence of the struts. The corresponding power loss at hub-height wind speed u ¼6 m/s amounts to: …”