RU2210096C1 - Automatic system measuring and computing wind parameters - Google Patents

Abstract

FIELD: weather forecasting. SUBSTANCE: invention can find use at meteorological stations employed in long-term weather forecasting and in design of power windmill installations and their experimental tests. System comprises measurement part incorporating meters measuring speed, pressure and direction of wind with electric pickups structurally arranged on base of weather cock and computing part including two multipliers and one divider meant to compute power of wind flow with cross-section of 1.0 sq m and density of this flow. System provides for metering of specific energy of flow with cross-section of 1.0 sq m with the aid of wind energy meter. EFFECT: increased informativity. 2 cl, 4 dwg

Description

 The invention relates to the field of wind energy, in particular to its information support.

 Known methods and devices for measuring such wind parameters as direction, pressure and speed [1-6]. [4] describes the operation of a weather vane, indicating the direction of the wind, with a device for measuring wind speed, made in the form of a plate that rotates around a fixed axis under the influence of wind force.

The disadvantage of such a device is the nonlinearity of the scale, which analytically can be represented in the form (1)
φ = arctan [ρτ • h • L • V ² : (2G)], (1)
where φ is the scale of the device is the angle of deviation of the plate from the vertical;
ρ is the density of the wind flow, kg / m ³ ;
h is the width of the plate, m;
L is the plate length, m;
V - wind speed, m / s;
G is the weight of the plate, N.

From (1) one can see a pure nonlinearity of the scale φ = f (ρ ₂ V ² ), therefore one can only speak roughly about the accuracy of such devices, although they are used in meteorology [4].

 In [5], methods and devices of pressure gauges are given that can be used for pressures of the order of several atmospheres.

The wind pressure, which analytically can be represented in the form (2), is much less
P = ρ • V ^2/2 (2)
where P is the wind pressure, N / m ² ;
ρ is the wind density, kg / m ³ ;
V is the speed, m / s;
When ρ = 1.3 kg / m ³ ; V = 10 m / s; P = 65 kg / m ² = 6.6 • 10 ^-4 kg / cm ² = 6.6 • 10 ^-4 atm.

 Thus, devices [5] for measuring wind pressure cannot be used.

 The aim of the invention is to increase the information content of wind parameters.

This goal is solved by an automatic system in which such parameters as the direction, speed and pressure of the wind are simultaneously measured, which automatically calculate the density of the medium, the magnitude of the power of the wind flow with a cross-section of 1 m ² and the energy of such a flow during the reading T.

Figure 1 presents the structure of an automatic system, where it is indicated:
1 - pressure meter with electric sensor;
2 - wind speed meter with electric sensor;
3 - the first factor, the output of which is a signal proportional to the power of the cross section flow of 1 m ² ;
4 - the second factor, the output of which is proportional to V ² ;
5 - counter wind energy flow during time T;
6, 7, 8, 10, 11 - indicators;
P is the wind pressure;
ρ is the wind density;
V is the wind speed;
u _p u _v , u _n , u _w - electrical outputs of pressure sensors, speed, power and energy meter;
9 - divider.

 The diagram does not show amplifiers after multipliers 3 and 4, in which the amplification factors decrease by about 100 times.

 If 1 and 2 are located in the wind, then the remaining elements are indoors, to which information from 1 and 2 comes from the cable.

 The information obtained at the output of the automatic system can be used by the weather service for long-term weather forecasting, as well as in the design of power wind turbines and their pilot tests.

 In FIG. Figure 2 shows a design drawing in which pressure, speed and wind direction meters with electric sensors are connected on the basis of a weather vane with an exit through the cable to the control room.

In figure 2, the following notation:
12 - a cable through which information about the pressure, speed and direction of the wind is transmitted from the sensors to the control room;
13 - supports rigidly fixing the stationary pipe 14 through which 12 is carried;
15 - a movable pipe connected through a thrust bearing 20 with a stationary 14;
16 - movable contact of the wind direction sensor;
17 - wings of the weather vane, fixed on 15;
18 - stand, mounted on 15, for the meter and the wind pressure sensor;
19 - stand for measuring and wind speed sensors, fixed at 15;
21 - wires from pressure sensors 22 of speed 13 with the blades of a wind turbine 23 and a wind direction sensor 25.

 Below, the design of the wings of the weather vane 17 and their connection with the pipe 15 and indicating the contact 16 are highlighted.

 The signal from the wind direction sensor 25 can be used in the automatic orientation system of power wind turbines.

 In FIG. 3 shows the design of 2 variants of the sensitive elements of the pressure meter.

In option a), the bellows is the sensitive element and the following notation is accepted:
26 - front cover to which the bellows 30 is attached;
27 — a cylinder to which 26 and a screen 31 are attached to increase sensitivity to wind pressure P;
28 - a back cover that attaches to 27;
29 - a rod that is attached to the bottom of the bellows 30;
X - wind direction and R.

Option b) presents the design of a spring piston type with a screen, where it is indicated:
32 - cylinder;
33 - spring, which is attached at one end to the cover 34, and the second to the movable piston 35;
36 is a screen in the form of a hollow truncated cone to increase sensitivity to wind pressure P;
X - wind direction.

 The difference between the options is only that in a) the bellows is stretched, and in b) the spring is removed in the presence of wind pressure R.

The analytical expression for the scale of both options is the same and can be represented as (2)
X = K _p • S • P, (2)
where X is the displacement of the flow in option a) or piston in b) under the action of pressure P;
To _p - the transfer coefficient of the sensing element, equal to the reciprocal of the stiffness of the bellows or spring;
S is the area of the bellows or piston.

If there is a screen (2) it will take the form (3)
X = K _p • S _e • sos2α • P, (3)
where S _e - the area of the input section of the screen;
α is the angle between the generatrix and the axis of the screen cone.

Since the value of P is several orders of magnitude less than atmospheric, for example, with ρ = 1.3 kg / m ³ , V = 10 m / s; p = 65 n / m ³ ≅ 6.6 kg / m ² = 6.6 • 10 ^-4 atm, then the necessary sensitivity to P according to (3) can be achieved due to the product K _p • S _e • cos2α, i.e. . by reducing the stiffness of the bellows or the spring, due to the area S _e and the choice of α.
With small limiting values of X _pr you can use differential inductive or capacitive sensors of small displacements, and for large - potentiometric.

 Figure 4 presents 3 options for measuring schemes for switching differential inductive, capacitive and potentiometric sensors.

The designations adopted in the options are as follows:
a) L ₁ and L ₂ - self-induction coefficients for decreasing and increasing gaps;
U ₀ - AC supply voltage;
U _o - output voltage proportional to the offset X and, respectively, R.

 R is the constant resistance.

b) C ₁ and C ₂ are capacitances, C ₁ is for an increasing gap, and C ₂ is for decreasing, at X = 0, P = 0, C ₁ = C ₂ .

c) R ₁ + R ₂ = R _n is the resistance of the potentiometer;
R ₁ is the resistance for the increasing gap equal to (R _n : 2) • (1 + K • X);
R ₂ is the resistance for a decreasing gap equal to (R _n : 2) • (1-K • X);
U _o - output voltage equal to U ₀ • K • X, where U ₀ - DC or AC power voltage.

 The device for measuring wind speed is a conventional paddle wind turbine, and as a sensor - a direct current microgenerator with excitation from permanent magnets.

 The device for measuring the direction of the wind is a conventional weather vane with an angular displacement sensor.

Thus, to increase the information content of wind parameters, which is important both for weather stations for long-term weather forecasting and design of wind turbine power plants and their experimental tests, an automatic system is proposed for measuring and calculating wind parameters, in which parameters such as direction are measured, wind speed and pressure are automatically transmitted to the control center, where the density, power and energy of the specific wind flow with a cross-section of 1 m ² are calculated.

 The obtained information on the parameters of direction, speed, pressure, density, power and energy for the specific wind flow significantly increases the information content about the energy side of the wind.

Sources of information
1. M.S.E., v. 7, p. 227, SE, 1959

 2. Ed. J.J. Traskel. Reference book on the technique of automatic regulation. M .: SEI, 1962, p. 17, 672-734.

 3. M.S.E., vol. 8, p. 477, G.N. SE, 1960.

 4. M.S.E., vol. 9, p. 1046, G.N. SE, 1960.

 5. Fundamentals of automatic regulation, t.2, ed. V.V. Solodovnikov. Elements of automatic control systems, part 1. Sensitive, amplifying and actuating elements. M .: GK-TIML, 1959, p. 51-54.

 6. V.A. Harutyunov. Electrical measuring instruments and measurements. M.-L. : SEI, 1958, p.137.

Claims (3)

1. An automatic system for measuring and calculating wind parameters, comprising measuring and computing units connected by a cable, while the measuring unit contains pressure meters, wind speed and direction, and a wind energy meter of the wind flow with a cross-section of 1 m ² , each meter and wind meter the energy of the wind flow with a cross section of 1 m ^{2 is} equipped with electric sensors, the computing unit contains a first multiplier for receiving a signal proportional to the power of the wind flow, by multiplying the signals from pressure and wind speed sensors, a second factor for squaring the speed sensor signal and a divider for receiving a signal proportional to wind density by dividing the signal of the wind pressure sensor by a value proportional to the square of the wind speed.  2. An automatic system for measuring and calculating wind parameters according to claim 1, characterized in that the wind pressure meter comprises a screen for increasing sensitivity to wind pressure, made in the form of a hollow truncated cone. 3. An automatic system for measuring and calculating wind parameters according to claim 1, characterized in that the wind energy counter of the wind flow with a cross-section of 1 m ² contains an electric micromotor with permanent magnets, the input of which receives a signal proportional to the wind power.

Images