FI118744B - Wind turbine wind measurement method - Google Patents

Description

118744

FIELD OF THE INVENTION FIELD OF THE INVENTION

The invention relates to a method for measuring wind power in a wind turbine as defined in the preamble of claim 1.

BACKGROUND OF THE INVENTION

Nowadays, at least one, often two, wind gauges are usually used to control wind turbines. In most cases, these are conventional cup anemometers or ultrasonic anemometers. The measured wind speed is used to control the power plant, especially during start-up and shut-down, but also for continuous comparison of rated power 15 and actual power to reveal any problem with power or an inaccurate measurement value of the anemometer.

Wind direction sensors are usually used as Wind Blades with an electrical output signal. 20 The ultrasonic anemometer also provides wind direction.

9 9 ϊ / .ϊ Wind direction signals serve the direction of the plant direction: **; and a very sudden and sudden change in wind direction.

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The problem with the current wind power f · · 25 mills where the rotor is located in front of the tower is that • · 1 ** \ I1

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placed on the outer side of the engine room behind the rotor »« 1 •• ί, supported by it, act as an exhaust rotor *. · ♦ 1 ·.

·· 30 Rotor exhaust flow does not match actual • 4 1 lii. the rotor blades are affected by the wind, but they are both · 1 "·?, with varying speed and direction and turbulent flow. · In particular, each rotor blade causes • 1 l | to emit an exhaust vortex that hits the measuring device ϊ 1ί · 35 immediately after passing the platform.

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Repeated long-term deviations in measurement results are corrected by a calibration curve obtained from measurements of a separate wind measurement mast by comparing its results with the plant anemometer and 5 windbars.

PURPOSE OF THE INVENTION

The object of the invention is to reduce the aforementioned inaccuracies.

In particular, it is an object of the present invention to provide a novel method of measuring which allows both the direction and the velocity of the wind acting on the wind turbine rotor to be measured as smoothly and without error as possible.

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SUMMARY OF THE INVENTION

The measuring method according to the invention is characterized in what is set forth in claim 1.

The wind turbine wind measurement method according to the invention is directed to a wind turbine comprising a ge.,.? * · Rotated horizontally at the end of the mast. a machine room equipped with a generator and a generator * · # ·· connected to and arranged to rotate the shaft of the generator * · # ·· 25 · vertically rotating two or more! * pressurized rotor. In addition, • · • «* is equipped with a measuring device for measuring the direction and velocity of the wind ····. In accordance with the invention- *** # ·· * ·. ··! ti determines the blade angle areas of the rotor blades, ·· * 30 where the blades affect the measurement signal, ·· · ϊ »ti and leaves the measurement signal from the measuring device · * · * ?. without regard to defined blade angles.

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In other words, according to the invention, the measurement signals obtained from the abnormal flow conditions caused by the blades ϊ * iJ 35 are not taken into account in the wind power control, but such momentarily erroneous signals are discarded.

In one embodiment of the invention, the measurement signal is locked to its instantaneous value during said blade angle region before the onset of the Ia-5 angle region. Thus, with the rotor blade in front of the measuring device and affecting the flow of air into the measuring device, the new measuring signal is not taken from the measuring device, but is replaced by previously obtained information.

Because interference-free airflow can be relatively variable and uneven, it is also possible that the measurement signal is not locked to its instantaneous value prior to the onset of the paddle area, but to a suitable average value determined over a period of time prior to locking.

In another embodiment of the invention, at least two separate measuring devices are disposed at a distance from each other such that the said blade angle areas do not overlap, i.e. overlap in the direction of the air flow. In this case, the measured signal ϊ / .ϊ will be received intermittently, always varying *: 1 · outside of said blade angle range. *. ·? 1 '. of the airflow. In other words • f · · • ♦ ·· 25, when there are two or more measuring devices and I * ·, ♦ ·· „·. properly spaced • 1 · there is always a measuring device in the undisturbed air flow so that it can be measured correctly

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···· knowledge. Thus, the measurement · 2 ·· * 'used to control the wind turbine is assembled from two or more signals from different measuring devices.

M · • The wind power Λ * measurement method of the invention has significant advantages over the known * ·· · u technique. The adjustment of the wind turbine is obtained by • «·» • · M «2 *. 35 more accurate and faster because the control · ·, '*! the information is always correct and uninterrupted.

: 2: The benefit of the method is especially significant in sudden • · 4 118744 wind deviations, as the directional signal becomes more reliable, allowing for steeper observation limits when dealing with rapid changes in wind direction.

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LIST OF FIGURES

The invention will now be described in more detail by way of example with reference to the accompanying drawing, in which Figure 1 shows a wind turbine using the measuring method according to the invention, Figure 2 schematically shows an embodiment of the invention and Figure 3 schematically shows another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 shows a wind turbine comprising an engine room 2 containing a generator at the end of the mast 1. The Ko-20 room 2 is arranged horizontally relative to the mast: rotatable. The generator shaft is connected to rotate the generator in a substantially vertical plane • •. row rotor 3 with three blades 6 at even intervals, ie • ··· · 'J r * I **. Every 120 degrees. Above the machine room 2, two measuring devices 4 and 5 are mounted on its outer surface [e # 1 * 25], which are located as far apart as possible, i.e. at the extreme edges of the engine room in the plane of rotation of the blades.

ϊ * # 1ίί · Measuring devices 4 and 5 are located downstream of rotor 3 in the wind direction 1 *** 1 30, i.e., in the main rotation of the rotor ··· JV1. Measuring instruments have sensors for wind · 1 · ** for both speed and direction.

• TT φ * ·· 1 Airflow on blade 6 causes rotation

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* <\ j rotation while the shoulder affects the subsequent • 1 · * \ 1 '\\ 35 exhaust air flow, so that the exhaust flow rate. is less than the velocity of the front flow of the blade • · · 5 118744 and the direction of the exhaust flow is different from that of the front flow. At the same time, there is irregular turbulence in the exhaust flow. However, the distance between the measuring devices 4 and 5 is so great that the exhaust flow leaving the single blade of the y-5 is never simultaneously applied to both measuring devices. In this way, one of the measuring devices 4 and 5 always receives an undisturbed flow of air between the two blades having the original direction and velocity.

Figure 2 shows a method according to the invention when only one measuring device 4 is used. The upper curve of Figure 2 shows the wind speed measured by the measuring device as a function of time. The wind speed is relatively steady, but the measurement signal 15 has an interference 7 whenever the blade passes the measuring device. This is eliminated by determining the blade angles between which interference occurs and replacing the signal from the measuring device during that time t1 to t2 with a constant signal 8 equal to the instantaneous value of the signal prior to the beginning of the blade angle range in question.

# · Φ. Another embodiment of the invention is illustrated in Figure · ··· 3 and achieves continuous, uninterrupted control. The method Me-: 1 ·,? 1 employs two measuring devices, from which • · 1 ·. ·. '· £ · .1 25 obtain corresponding measurement signals 9 and 10, • · ·. ··'. 1 which illustrate the wind speed at the rotor exhaust flow. Both signals 9 and 10 have similar · ·%.

* i ## s blade interference 11, but the measuring devices are positioned in the exhaust flow so that the interferences * · 1 ···· 30 are never simultaneously but alternately • · · ·

Gum. Thus, in accordance with the invention, the signals 9 and 10 provided by the measuring devices are combined with the resultant signal.

Vv1 [1 lix 12 such that the interference point of the signal cor .'V ** is always matched with the interference signal of the other signal.

• § · 35 The substitution can be made by first 9 of the first 1 · · · · 1.φ signals being considered as the main signal and only • · · · · 118744 e its interference part t1 - t2 is always replaced by the corresponding part of the second signal 10.

Another possibility is that the resultant signal 12 is formed half of both signals 5 9 and 10 by always changing the signal to be received to the resultant signal just before interference 11, i.e. signal 10 between tl-t3, signal 9 between t3-t5, signal 10 between t5-tl, etc. In this way, the interference will surely be able to level off the signal before it is again incorporated into the resultant signal and the interfering and correct measurement of the wind impinged on the rotor is obtained.

The above examples illustrate the measurement of wind speed, but in the same way the measurement of the wind direction is carried out by the method according to the invention.

The invention is not limited to the above examples only, but many modifications are possible within the scope of the inventive idea defined in the claims.

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Claims (4)

A method of measuring the wind in a wind turbine, comprising a wind turbine at the end of a mast (1), a machine room (2) arranged to be rotatable in the horizontal plane and provided with a generator, and a two- or multi-blade rotor (3). ) which essentially rotates in a vertical plane and is coupled to the axis of the generator and is arranged to rotate it, a measuring device (4, 5) providing a measurement signal is arranged in the outflow current of the rotor for measuring the direction of the wind and speed, characterized in that the blade angle regions of the blades (6) of the rotor (3) within which the blades interfere with the measurement signal and within these determined blade angle ranges are taken into account the measurement signal (4, 5). Measurement method according to claim 1, characterized in that the measurement signal is read during the time of said blade angle range at the instantaneous value which occurred before the start of the blade angle range. 20 3. Measurement method according to claim 1, characterized in that the measurement signal is read during the time of said blade angle range at the mean value which occurred before the start of the blade angle range. # · Φ · 4. Measurement method according to claim 1, characterized in - • · * In the drawing thereof, at least two separate measuring devices (4, • 1 * ··· [5) are placed in the outflow Current of the rotor (3) at a distance from one another says that their said ** 1 blade angle ranges do not overlap, whereby the measurement signal to be used is periodically varied, always always outside said blade angle range with a measuring device in an undisturbed air flow. ·· • ♦ • ·· ··· • · · · · · ♦ ♦ · · · ·· · · · · · · · · ♦ ♦ ♦ ♦ · ·