JP2009303324A - Main circuit of wind energy conversion system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of a conventional system that the number of revolutions of windmills decreases at large ripple of wind velocity, in a generating set for distributed power sources using a permanent magnet type generator which has many kinds of coils so as to get maximum output from wind power without a PWM converter. <P>SOLUTION: In the main circuit of a wind energy conversion system, which rectifies the AC output of the permanent magnet type generator that is driven by windmills and is constituted of a plurality of coils for generating different induced voltage effective values by individual rectifiers through individual reactors and adds the DC output of the individual rectifiers and outputs it to outside, the individual reactors are provided with taps, and a contactor, which short-circuits the taps of the individual reactors, is provided. This main circuit detects the standard deviation of wind velocity, and in case that the standard deviation of the wind velocity is larger than a certain value, it opens the above contactor, and in case that the standard deviation of the wind velocity is smaller than the certain value, it short-circuits the contactor thereby preventing the decrease of the number of revolutions of the windmills. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a main circuit of a wind power generator that extracts a rough maximum output that can be obtained from a wind from a permanent magnet generator driven by a wind turbine, regardless of the value of wind speed, and in particular, a permanent magnet type. The present invention relates to a main circuit of a wind turbine generator that charges a constant voltage power source without using a PWM converter from a generator.

  In order to obtain an approximate maximum output from a permanent magnet generator connected to a wind turbine, the applicant first converts AC to DC without using a PWM converter. A wind turbine generator is proposed in which each rectifier is connected in series to each other through a reactor to an AC output terminal of a plurality of windings that generate power, and the DC outputs of these rectifiers are connected in parallel and output to the outside (for example, (See Patent Document 1).

This prior application technique will be described in detail with reference to the main circuit diagram of the wind turbine generator connected to the wind turbine of FIG.
In FIG. 8, 1 is a wind power generator of the prior application, 2 is a permanent magnet generator, 31 and 32 are first and second reactors, 41 and 42 are first and second rectifiers, 10 is a windmill, 11 is a positive output terminal, 12 is a negative output terminal, and 13 is a battery.
In FIG. 8, the permanent magnet generator 2 has two types of winding numbers and shows a three-phase case.

In FIG. 8, since the number of turns of the permanent magnet generator 2 is small, the AC output terminal W1 of the first winding having a low induced voltage effective value is connected to the first reactor 31 and further to the first rectifier 41. Connected.
The AC output terminal W2 of the second winding having a large number of turns is connected to the second reactor 32 and further connected to the second rectifier 42.
The direct current sides of the first and second rectifiers 41 and 42 are connected in parallel to the positive output terminal 11 and the negative output terminal 12, and the total output of each winding is charged in the battery 13.

A method for obtaining an approximate maximum wind turbine output from the wind turbine generator 1 configured as described above will be described below.
FIG. 7 is a diagram for explaining the relationship between the peripheral speed ratio β of the windmill and the output coefficient Cp. When the shape of the windmill is determined in this way, the output coefficient Cp with respect to the peripheral speed ratio β (= 2π × windmill speed / wind speed) is uniquely determined. That is, since the peripheral speed ratio β that is the maximum output of the windmill is constant, the rotational speed of the windmill that is the maximum output of the windmill is proportional. Further, since the maximum output of the windmill is proportional to the cube of the wind speed, the maximum output of the windmill has a cube characteristic with respect to the number of rotations of the windmill.

  That is, in order to obtain the maximum output from the wind, once the wind turbine rotation speed N is determined, the output P of the permanent magnet generator 2 at that time may be uniquely set to a value on the maximum output curve Pt. Represents. In practice, the expression of matching the input of the permanent magnet generator 2 and the maximum output of the wind turbine is preferable. However, in this patent specification, the loss of the wind power generator 1 including the permanent magnet generator 2 is ignored. explain.

  FIG. 6 is an explanatory diagram in the case where the direct current output of the wind turbine generator 1 targeted by the prior application technology is connected to a constant voltage power source such as a battery, and the first and second permanent magnet generators 2 of the wind turbine generator 1 are shown in FIG. Each output of the second winding is different from the effective value of the induced voltage of each winding, and the voltage drop due to the internal inductance of each winding and the reactor connected to each output terminal. P1 and P2 shown in FIG.

That is, when the wind turbine rotational speed N is low, the voltage generated in the first and second windings in the permanent magnet generator 2 is lower than the battery voltage Vb, so the battery 13 is not charged.
However, when the wind turbine rotational speed N increases and becomes near N2, the voltage generated by the second winding becomes equal to or higher than the battery voltage Vb, so that current starts to flow through the second winding, and the wind turbine rotational speed N increases. At the same time, the current rises and the output by the second winding becomes P2.
At this time, even if the wind turbine rotation speed N is increased and the induced voltage is increased, the battery voltage is substantially constant, but the internal inductance of the second winding and the impedance by the second reactor 5 are proportional to the frequency. Therefore, the output P2 only increases gradually.
As for the first winding, output begins to be obtained as the rotational speed N further increases, but a large output can be obtained because the internal inductance of the first winding and the first reactor 4 are small.

FIG. 5 is a diagram illustrating an output to a constant voltage source such as a battery of a wind turbine generator targeted by the prior application.
The total output obtained by adding the outputs P1 and P2 of the first and second windings in the permanent magnet generator 2 is an approximate output curve Ps.
JP 2004-64928 (FIG. 1)

Since the windmill has a large moment of inertia, even if the wind speed fluctuates greatly, the windmill rotation speed hardly changes, and the average torque generated by the windmill decreases. This relationship will be described with reference to FIG. In FIG. 4, when the wind speed fluctuates with respect to the average value, the rotational speed of the windmill hardly changes, so the peripheral speed ratio β changes in inverse proportion to the wind speed. As shown by the correlated circumferential speed ratio fluctuation range in FIG. 7, the output coefficient becomes small and the torque becomes small at locations where the circumferential speed ratio is extremely large and small within the range of the circumferential speed ratio variation range. Therefore, in particular, as shown at time point A in FIG. 4, when the wind speed increases, the torque usually increases. However, the peripheral speed ratio decreases and the wind turbine torque decreases. .
In this way, the average value of the wind turbine torque is reduced, and the wind turbine rotation speed is reduced. Therefore, there is a problem that the output of the wind turbine generator is also reduced. When the wind turbine rotational speed is decreased, the lower limit of the peripheral speed ratio fluctuation range in FIG. 7 is lowered, and a vicious circle is further formed in which the wind turbine torque is further decreased.

  The present invention has been made in view of the above circumstances. The main object of the present invention is to perform PWM control from a permanent magnet generator without decelerating the rotational speed of the windmill even when the wind speed changes greatly. It is to provide a main circuit of a wind turbine generator that charges a constant voltage power source without using a converter.

  Therefore, in the present invention, the alternating current output of a permanent magnet generator that is driven by a wind turbine and includes a plurality of windings that generate different induced voltage effective values is rectified by individual rectifiers through individual reactors, In the main circuit of the wind turbine generator that adds the direct current output of the individual rectifier and outputs it to the outside, the standard deviation of the wind speed is detected, a tap is provided in the individual reactor, and the standard deviation of the wind speed is larger than a certain value. In some cases, the taps of the individual reactors are opened, and when the standard deviation of the wind speed is smaller than a certain value, a contactor for short-circuiting the taps of the individual reactors is provided.

  When the fluctuation of the wind speed is large, by opening the contactor, the approximate output curve Ps is shifted to the right side of the maximum output curve Pt, and the maximum output cannot be obtained from the windmill. A main circuit of a wind turbine generator that obtains the maximum output from the windmill by making the maximum output curve Pt and the approximate output curve Ps substantially coincident by short-circuiting the contactor when the wind speed fluctuation is small is provided. it can.

  In the present invention, the AC output of a permanent magnet generator composed of a plurality of windings driven by a wind turbine and generating different induced voltage effective values is rectified by individual rectifiers through individual reactors, In the main circuit of the wind turbine generator that adds the DC output of the rectifier and outputs it to the outside, a tap is provided on the individual reactor, and a contactor that short-circuits the tap of the individual reactor is provided to detect the standard deviation of the wind speed When the standard deviation of the wind speed is larger than a certain value, the contactor is opened, and when the standard deviation of the wind speed is smaller than a certain value, the contactor is short-circuited.

FIG. 1 is a diagram for explaining a main circuit of a wind turbine generator that obtains a DC output from a windmill according to the present invention.
In the figure, 51 and 52 are first and second tapped reactors, 61 and 62 are first and second contactors, 7 is a wind speed deviation calculating circuit, 8 is a contactor control circuit, and FIG. The same number represents the same component. Hereinafter, FIG. 1 will be described with reference to FIGS. 2 and 3 illustrating the principle of the present invention.

A first tapped reactor 51 and a first rectifier 41 are connected in series to the AC output terminal of the first winding W1 having a small number of turns. A first contactor 61 is connected to the first tapped reactor 51 in parallel. A second tapped reactor 52 is connected in series to the AC output terminal of the second winding W2 having a large number of turns, and a second rectifier 42 is further connected. A second contactor 62 is connected in parallel to the second tapped reactor 52.
The outputs of the first rectifier 41 and the second rectifier 42 are connected in parallel, and the total DC output is charged in the battery 13.

  FIGS. 2 and 3 show the AC output of the permanent magnet generator 2 when the first and second contactors 61 and 62 are turned OFF and the inductance values of the first and second tapped reactors 51 and 52 are increased. Show. A current smaller than the output P2 of FIG. 6 flows through the AC output terminal of the second winding W2 having a large number of turns, and becomes the output P2 ′ of FIG. The output of the first winding W1 having a small number of turns is smaller than that of P1 in FIG. 6, and becomes an output P1 ′ in FIG. As shown in FIG. 2, the total DC output of the second winding W2 having a large number of turns and the first winding W1 having a small number of turns becomes an approximate output curve Ps' and is shifted to the right side of the maximum output curve Pt. Can be obtained. That is, the output of the wind power generator 1 decreases.

  When the first and second contactors 61 and 62 are turned ON, since the impedance connected to the AC output of the permanent magnet generator 2 is reduced, a large current flows, as shown in FIG. 5 and FIG. In addition, the maximum output curve Pt and the approximate output curve Ps can be substantially matched to obtain the maximum output from the windmill. Such approximate output is the same as that of the conventional invention.

The wind speed deviation calculation circuit 7 detects the wind speed around the wind turbine 10 to obtain the standard deviation σ of the wind speed. As for the standard deviation σ of the wind speed, for example, the wind speed is measured at intervals of one second by an anemometer (not shown) to obtain an average wind speed for 10 minutes, and the standard deviation σ of the wind speed is calculated at any time to the contactor control circuit 8. Output. The contactor control circuit 8 outputs a contactor control signal S for turning off the first and second contactors 61 and 62 when the standard deviation σ of the wind speed becomes a large value greater than a certain value. The inductance values of the second tapped reactors 51 and 52 are increased. The output at this time is an approximate output curve Ps ′ as shown in FIG.
When the standard deviation σ of the wind speed falls below a certain value, the contactor control signal S for turning on the first and second tapped reactors 51 and 52 is output, and the first and second tapped reactors 51 are output. And the inductance value of 52 is made small. The output at this time is an approximate output curve Ps as shown in FIG.

Thus, when the standard deviation value σ of the wind speed is large, by increasing the first and second tapped reactors 51 and 52, the load applied to the windmill is reduced, and the average torque of the windmill 10 due to the wind speed fluctuation is reduced. Even if it falls, the stable output can be taken out from the windmill 10 without the windmill rotation speed N decreasing.
Here, the same output increase / decrease effect can be obtained even if the inductance value of the second tapped reactor 52 is appropriately selected and the second contactor 62 is turned ON / OFF by the contactor control signal S. .

It is a figure for demonstrating the main circuit of the wind power generator driven by the windmill of this invention. It is a figure for demonstrating the total output in the Example at the time of reducing the output of the wind power generator which this application makes object. It is a figure for demonstrating the output of each coil | winding in the Example at the time of reducing the output of the wind power generator which this application makes object. It is a figure for demonstrating an output of the windmill torque when a wind speed fluctuates. It is a figure for demonstrating the total output of the wind power generator which a prior application makes object. It is a figure for demonstrating the output of each coil | winding of the wind power generator which a prior application makes object. It is a figure for demonstrating the relationship between the output coefficient of a windmill, and a circumferential speed ratio. It is a main circuit diagram of the wind power generator of the prior application.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wind power generator 2 Permanent magnet generator 31, 32 1st, 2nd reactor 41, 42 1st, 2nd rectifier 51, 52 1st, 2nd reactor with a tap 61, 62 1st, 2nd 7 Contactor control circuit 10 Contactor control circuit 10 Windmill 11 Positive output terminal 12 Negative output terminal 13 Battery

Claims (1)

The AC output of a permanent magnet generator composed of a plurality of windings driven by a wind turbine and generating different induced voltage effective values is rectified by an individual rectifier through an individual reactor, and the direct current of the individual rectifier In the main circuit of the wind turbine generator that adds the output and outputs to the outside, the individual reactor is provided with a tap, a contactor that short-circuits the individual reactor tap is provided, a standard deviation of the wind speed is detected, and the wind speed A main circuit of a wind turbine generator, wherein the contactor is opened when a standard deviation of the wind speed is larger than a certain value, and the contactor is short-circuited when the standard deviation of the wind speed is smaller than a certain value.

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