RU2353799C1 - Method for operation of autonomous wind-electric station - Google Patents

Abstract

FIELD: engines and pumps. ^ SUBSTANCE: invention may be used for power supply of autonomous consumers. Method includes transformation of windwheel energy with uncontrolled angle of wings installation into electric energy, its accumulation in accumulator battery, DC inversion into AC with further supply to consumer. The angle of wings installation is calculated for rated rotation frequency of windwheel. In process of operation at wind speeds that differ from design speed, rated frequency of windwheel rotation is stabilized under load, for that purpose windwheel is able to automatically control coefficient of wind energy extraction with the help of electrodynamic braking of generator by accumulator battery charging current, by rated value of which capacitance of accumulator battery is selected. Battery voltage is accepted by means of experimental selection of accumulators number in battery, which provides for rated frequency of windwheel rotation. ^ EFFECT: increased efficiency, reliability and durability of wind-electric station operation, and also expansion of used wind speeds range.

Description

The invention relates to wind energy and can be used to power autonomous consumers.

A known method of controlling a wind power installation (application No. 2005112903), including orienting the blades of the wind wheel relative to the plane of its rotation in the range of angles from structurally minimal to the vane in the mode of acceleration, working or stopping the wind wheel, keeping the blades at the installation angle, at which the rotation of the wind wheel is stabilized in the nominal range angular speed of the operating mode, on / off load and / or brake. To implement this method requires a complex control system and a special mechanism for adjusting the angle of installation of the blades. In addition to complicating the design and control system, the disadvantage of this method is the occurrence of self-oscillation of the blades that occur when the angle of their installation during operation, which reduces the durability of the wind wheel and worsens the operating conditions.

Known wind power (application No. 2003103190), containing a wind wheel connected to a generator, a voltage regulator, the input of which is connected to the stator windings of the generator, a rectifier, the input of which is connected to the output of the voltage regulator, a battery and a payload block connected to the output of the rectifier, a ballast unit resistances connected to the voltage regulator, as well as the ballast power regulator, the input of which is connected to the voltage regulator, and the output is connected to the input of the ballast resistor block s. This device allows you to implement a method of stabilizing the charge current of the battery by regulating the voltage at the input of the rectifier. However, the presence of ballast resistances leads to a loss of energy on them, which reduces the efficiency of the wind farm.

Known wind turbine and a method of regulating its power (application No. 95110147). The windmill contains two wind wheels with unregulated angles of installation of the wings, and power regulation consists in the selective connection of the wind wheels to the electric generator. This wind turbine has a bulky design that reduces the reliability of its operation.

The present invention solves the problem of increasing the efficiency, reliability and durability of the wind farm, as well as expanding the range of wind speeds used.

To achieve the specified technical result, the wing angle is calculated at the nominal rotational speed of the wind wheel and made unchanged, and during operation at wind speeds different from the calculated one, the nominal speed of the wind wheel is stabilized under load by giving the wind wheel the ability to automatically adjust the wind energy selection coefficient due to electrodynamic braking generator by the charge current of the battery, the nominal value of which selects the battery capacity batteries, and its voltage is taken by experimental selection of the number of batteries in the battery, providing the nominal frequency of rotation of the wind wheel.

A distinctive feature of the proposed method is the stabilization of the nominal frequency of rotation of the wind wheel under load by giving the wind wheel with unregulated angles of wing installation the ability to automatically adjust the coefficient of selection of wind energy by electrodynamically braking the generator with the battery charge current.

As a result of a search by sources of patent and scientific and technical information, a sign characterizing the proposed method of operation of an autonomous wind farm was not found. Thus, the present invention meets the criterion of novelty.

Based on a comparative analysis of the proposed technical solution with the prior art, it can be argued that between the totality of signs, including distinctive, and their functions and goals achieved, there is an unobvious causal relationship. From this we can conclude that the technical solution in the proposed method does not follow explicitly from the prior art and, therefore, meets the criterion of "inventive step".

The proposed technical solution has application in the working methods and designs of autonomous wind power stations produced by NPO Vetrotechnika CJSC, and, therefore, meets the criterion of “industrial applicability”.

The proposed method is as follows.

In the kinematic calculation of a wind turbine, wind power sets:

power N _{g of the} generator, the nominal frequency of rotation ω _{n of the} wind wheel, the preliminary value of the nominal coefficient ξ _{p of the} selection of wind energy, the preliminary value of the nominal speed V _{p of the} wind at which the power N _g is generated. Based on the given values, the well-known formula determines the required radius R of the wind wheel

where η is the efficiency of the transmission between the wind wheel and the generator;

ρ _n - air density under normal atmospheric conditions.

Using the well-known formula, the nominal speed Z _{n of the} wind wheel is determined

Using the value of Z _n , according to the well-known method of aerodynamic calculation of a wind wheel for characteristic wing sections along its axis, installation angles φ of profiles, width b and thickness δ are determined.

The data obtained using the method of aerodynamic calculation of a wind wheel are used to determine the actual value of the nominal coefficient ξ _p selection of wind energy. Then, using the formula (1), the actual value of the nominal wind speed V _n is calculated, at which the power N _g

Manufactured taking into account the above calculations, the wind farm is supplied with a storage battery (AB), the parameters of which are assigned as follows. The capacity C _{a is} set based on the value of the rated current In of the battery charge, which is determined by the formula

where k _cx is the coefficient of the rectifier circuit;

U _D is the rated voltage of the generator.

Then, for example, when using acid batteries according to the standards - With _a = 5 · I _n . The preliminary value of the voltage U _{A of the} battery (the number of series-connected batteries) is set equal to

Example. Given: N _g = 30 kW, U _D = 380 V, k _cx = 1.355. Then

I _n = 30 · 10 ³ / (1.355 · 380) = 58.3 A, _Ca = 5 · 58.3 = 291.5 Ah (the closest typical value is 300 Ah), and U _A = 1.355 · 380 = 514, 9 V (the closest typical value for acid batteries, the rated voltage of each of which is 2 V, is 516 V).

A wind farm for implementing the method necessarily contains a wind speed sensor, a normally closed electric brake that keeps the wind wheel from rotating, and a control controller.

The operation of a wind farm, the parameters of which are assigned taking into account formulas (1) - (6), is carried out as follows. In the event of a wind having a speed of the operating range (3-25 m / s), the controller opens the brake pads by the signal of the wind speed sensor. Having obtained a degree of freedom, the wind wheel accelerates the generator rotor to an angular velocity corresponding to the start of the generator self-excitation. The rectified voltage of the generator stator is supplied to the AB terminals. At that moment in time, when the rectified voltage of the generator begins to exceed the value of the emf AB, the generator receives an electric load corresponding to the charging power of the AB. From this moment, the generator, as a source of electricity, and AB, as a receiver of electricity, are in a stable interaction. This interaction is to maintain a balance between the produced and consumed capacities. The specified balance leads to stabilization of the angular velocity of the generator at a strictly defined value, which does not depend on changes in wind speed. This is due to the fact that a change in wind speed leads to an increase in the power produced by the generator, according to expression (3). Moreover, according to expression (2), an increase in the angular velocity of the wind wheel and the kinematically associated generator should occur. However, an increase in the angular velocity of the generator is accompanied by an increase in its voltage and, consequently, an increase in the charge current of the battery. Since the internal resistance of the battery is much less than the resistance of the generator stator, an increase in the charge current of the battery and, consequently, the current of the stator winding of the generator creates an electrodynamic braking of the generator and the kinematically associated wind wheel. Since the wind wheel is driven into rotation by a progressively moving stream of air having elastic properties, the braking of the wind wheel leads to a partial stall of the flow on the wings. At the same time, part of the volume of air involved in the rotation of the wind wheel is passed through it, reducing the coefficient of selection of wind energy by the wind wheel. Therefore, according to the formula (2), the speed value Z of the wind wheel decreases from its nominal value. Thus, despite the increase in wind speed above the nominal value, the power of the wind wheel and, accordingly, the power of the generator is maintained at a constant level.

When the wind speed decreases from the nominal value, the angular velocity of the generator gradually decreases (due to the inertial properties of the wind wheel), the voltage of the generator decreases, the battery stops charging and the wind wheel switches to idle mode. Having lost the load, the wind wheel begins to increase the angular velocity to the nominal value, which again leads to the appearance of a charging current. This transition process continues until the equality of the generation and charging capacities of the batteries is established. Consequently, at wind speeds less than the nominal value, the charging power of the battery always corresponds to the power produced by the wind wheel with the generator, with a constant value of the angular speed of the wind wheel.

The pre-selected voltage value U _A AB (the number of batteries connected in series) is adjusted for each new wind farm using a special experiment. The need for such an experiment is due to the fact that when equipping a wind power station with an AB, the internal resistance of a charged AB is not known in advance, and its direct measurement is fraught with certain difficulties and does not guarantee an accurate result. Since the value of the internal resistance of the battery affects the value of the charging current of the battery when a certain voltage is applied to its terminals, in the proposed method, the required value of the angular velocity of the generator (and therefore the wind wheel) is proportionally dependent on this resistance.

The experiments show that the selection of the number of batteries in the battery, providing the nominal frequency of rotation of the wind wheel, occurs by adding or decreasing 2 ÷ 3 batteries from the initially specified amount, providing a pre-selected voltage value U _A AB.

The experimental selection of the number of batteries in the battery, providing the rated frequency of rotation of the wind wheel, is as follows.

The wind turbine transmission is equipped with a tachometer showing the angular speed of the wind wheel and, accordingly, of the generator. AB with a pre-selected voltage value U _{A is} connected to the output of the rectifier of the electric system of the wind farm, the input of which is connected to the stator windings of the generator. A wind farm is being commissioned. With the steady-state charging mode, the AB measures the actual value of the angular velocity ω _{d of the} wind wheel, which is compared with the nominal value ω _n . If ω _d <ω _n , then the wind wheel is braked and 1, 2 or 3 batteries are sequentially added to the battery, and the wind power station is put into operation again and the value of ω _{d is} measured. These actions are carried out until the equality ω _d = ω _{N is established} .

If the initial measurement shows that ω _d > ω _n , then 1, 2 or 3 batteries are sequentially disconnected from the battery during shutdown of the wind farm, the wind farm is commissioned and the value of ω _{d is} measured. These actions are carried out until the equality ω _d = ω _{N is established} .

The proposed method of operation of an autonomous wind power station has been repeatedly tested on products and is effectively used in most practical developments of NPO Vetrotechnika CJSC.

Claims (1)

The method of operation of an autonomous wind power station, according to which a wind wheel with an unregulated angle of wing installation is used, which includes converting the energy of the wind wheel into electrical energy, accumulating it in a battery, inverting direct current into alternating current and then supplying it to the consumer, characterized in that the wing installation angle is calculated at the nominal the frequency of rotation of the wind wheel, and during operation at wind speeds other than the calculated one stabilize the nominal frequency of rotation the wind wheel under load, for which the wind wheel is given the opportunity to automatically adjust the coefficient of selection of wind energy by electrodynamically braking the generator with the battery’s charge current, the nominal value of which selects the capacity of the battery, and its voltage is taken by experimental selection of the number of batteries in the battery, providing the nominal frequency of rotation of the wind wheel .