JPH08322298A - Wind power generating apparatus - Google Patents

Abstract

PURPOSE: To start a windmill securely and improve the power generating efficiency in a low wind velocity range. CONSTITUTION: A generator 3 which is driven by a windmill 1 is connected to a power system K through a generation controller 4 composed of a converter 41 and an inverter 43. If it is decided that, although a wind velocity is a generation enabling velocity, a rotor revolution N is No (rotor stopping revolution) <=N<=NP (generation starting revolution) by a wind velocity discriminator 421 and a revolution discriminator 422, the output current of the converter 41 is controlled in accordance with the output current characteristics in an output regulator 423, the output current of the converter 41 which is detected by a current detector CT and the rotor revolution N and the power running of the generator 3 is started. When the rotor revolution N reaches the generation starting revolution NP, the operation of the generator 3 is switched to the regenerative operation to start the generation. If the windmill 1 is not started even at the generation enabling wind velocity, the rotor 3a is forcibly turned by the power running to start the generation securely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wind power generator for converting wind energy into electric energy, and more particularly to power generation control for increasing power generation efficiency at low wind speed.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 62-284969, by adjusting the pitch angle of a propeller, the number of revolutions of a rotor can be kept constant regardless of changes in wind speed, and the output can be reduced. There is known a wind speed power generation device that keeps it constant.

FIG. 9 is a characteristic diagram showing the rotor output torque with respect to the rotor speed. As shown in FIG. 9, the rotor output torque has a peak (maximum torque), and the pitch angle β of the propeller increases as it increases. since the rotor rotational speed produces a maximal torque tau _MAX N and a maximum torque tau _MAX is decreased, in the pitch angle can be controlled wind turbine generator,
In general, when the wind turbine is started, the pitch angle β of the propeller is set to a start pitch angle β _S larger than the pitch angle β during operation to improve the start characteristics of the wind turbine.

[0004]

In the conventional wind power generator capable of controlling the pitch angle, the pitch angle β is made large at the time of start-up so that the wind turbine can be started even at a wind speed V as low as possible. When the angle β is increased, the maximum value τ _MAX of the rotor output torque is decreased, so that the wind speed V that can be started has a certain limit (see FIG. 9).

On the other hand, when the wind turbine is started, the frictional resistance of the bearings of the rotor and the gears of the gearbox connected to the rotor becomes maximum at the start of rotation, and the maximum resistance value is not constant, so it is set in advance. It is difficult to reliably start the wind turbine at the wind speed V or higher.

The pitch angle β is set by rotating the propeller support shaft with hydraulic pressure or an electric motor. The method of starting the wind turbine by the starting pitch angle is such that the wind speed V _{S at} which the wind speed V can be started. In the case where the propeller pitch angle β changes, the propeller pitch angle β is frequently switched between the starting pitch angle β _S and the rated pitch angle β _C according to the change in the wind speed V, which is disadvantageous in terms of durability.

It is possible to connect the induction generator directly to the electric power system via a switch and forcibly start the induction generation as a motor in the low wind speed region. However, in this case, the starting current of the induction generator is reduced. Since it is 5 to 6 times the rated current, a large current flows at the time of startup, and excessive startup torque is transmitted from the generator side to the bearings of the rotor, gears of the speed increaser, etc.
In addition to problems with the propeller's durability characteristics, it also violates the basic requirements for stable supply of generated power.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wind turbine generator capable of reliably starting a generator at a wind speed capable of generating electricity.

[0009]

According to the first aspect of the present invention,
An AC generator driven by the rotational force of a wind turbine, a first power conversion unit that controls the AC power output from the AC generator and converts the AC power into DC power, and the first power. A second power source that converts the DC power output from the conversion unit into AC power having a predetermined frequency and supplies the AC power to the power system.
Power conversion means, wind speed detection means for detecting the wind speed, rotation speed detection means for detecting the rotation speed of the rotor of the AC generator, and wind speed determination means for determining whether or not the wind speed is a wind speed at which power can be generated. And a rotation speed determination means for determining whether or not the rotation speed of the rotor has fallen below a preset continuous rotation speed, and a wind speed equal to or higher than a wind speed at which power can be generated and the rotation speed of the rotor. Is less than or equal to the rotational speed at which continuous rotation is possible, the first and second electric power conversion means are subjected to power running, and the rotational speed of the rotor is at least up to a preset self-startable rotational speed for power generation. And an operation control means for forcibly raising.

The invention according to claim 2 is, in the wind power generator, provided with current detection means for detecting an output current of the first power conversion means, and the operation control means is provided with a preset output current. The output current of the first power conversion means is controlled on the basis of the characteristics, the detected output current and the rotational speed of the rotor to drive the rotor with a constant torque.

According to a third aspect of the present invention, in the wind turbine generator, there is provided power detection means for detecting the output power of the first power conversion means, and the operation control means has a preset output power. Based on the characteristics, the detected output power, and the rotation speed of the rotor, the output power of the first power conversion means is controlled to drive the rotor at a constant output.

According to a fourth aspect of the present invention, in the wind turbine generator, the operation control means controls the excitation frequency of the first power conversion means based on a preset angular acceleration characteristic, and the rotor is rotated. Is driven by angular acceleration.

[0013]

According to the invention described in claim 1, when the wind speed is higher than the wind speed at which power can be generated, but the rotation speed of the rotor is lower than the rotation speed N _{O at} which continuous rotation is possible, the first and second power conversions are performed. The power generator is operated to drive the AC generator as a motor,
At least self-startable speed N _E (> for power generation
N _O) rotational speed of the rotor is forcibly increased to. Then, when the number of rotations of the rotor increases to N _P (> N _E ), the operation of the first and second power conversion means is switched to the regenerative operation, and the power generated by the AC generator is output to the power system. To be done.

According to the second aspect of the present invention, in the power running operation of the AC generator, the current of the output current of the first electric power conversion means and the rotation of the rotor are set to the target current value based on the preset output current characteristic. The number detection result is fed back to set the current control value, and the first output current is controlled based on this current control value. As a result, the rotor is rotationally driven with a predetermined constant torque characteristic and the number of revolutions N at which continuous rotation is possible.
It is raised to _E.

According to the third aspect of the present invention, in the power running operation of the AC generator, the current output power of the first power conversion means and the rotation of the rotor are set to the target power value based on the preset output power characteristic. The number detection result is fed back to set the power control value, and the first output current is controlled based on the power control value. As a result, the rotor is rotationally driven with a predetermined constant output characteristic and the rotational speed N _E at which continuous rotation is possible.
Is raised up to.

According to the fourth aspect of the present invention, the frequency control value is set based on the preset angular velocity characteristic, and the excitation frequency of the first power conversion means is controlled based on this frequency control value. As a result, the rotor is rotationally driven with a predetermined angular acceleration characteristic and raised to the rotational speed N _E at which continuous rotation is possible.

[0017]

1 is a block diagram of a first embodiment of a wind turbine generator according to the present invention. In the figure, a wind turbine main body 1 is a rotary machine section that converts wind energy into mechanical power, and two or several propellers 1b having a pitch angle β of which are protruded in a direction perpendicular to a rotary shaft 1a can be changed. And this propeller 1b
And a pitch angle changing device 1c for changing the pitch angle β of. The speed increaser 2 increases the rotation speed of the rotary shaft 1a at a predetermined ratio and transmits the rotation speed to the rotor 3a of the generator 3.

The generator 3 (indicated by G1 in the figure) is an energy conversion device composed of an induction machine, and is connected to the power system K via the power generation control device 4.

The power generation control device 4 controls the excitation frequency of the generator 3 and also controls the output power of the converter 41, the converter control circuit 42 which controls the driving of the converter 41, and the DC power output from the converter 41. 43 is reconverted into AC power of commercial frequency (50 Hz or 60 Hz) and supplied to the power system K, an inverter control circuit 44 for controlling the drive of this inverter 43, and an output voltage waveform from this inverter control circuit 44 is sine It is composed of a filter circuit 45 for shaping a wave.

The converter 41 is a three-phase converter using switching elements such as switching transistors and thyristors, and the inverter 43 is a three-phase inverter having the same structure as the converter 41. Converter 41 and inverter 43 are connected in parallel, and a smoothing capacitor C0 for smoothing a DC output is connected in parallel between the output terminals of converter 41.

The converter control circuit 42 includes a wind speed discriminator 421, a rotation speed discriminator 422, an output adjusting circuit 423, and P.
I (Proportional Integral) adjuster 424 (P in the figure)
Shown as I. ) And a current control circuit 425.

The wind speed discriminator 421 discriminates whether or not the wind speed V is within a wind speed range (V ₁ ≤V≤V ₂ ) at which power can be generated. The wind speed V detected by the wind speed detector 5 and the wind speed V are preset. The determined threshold values V ₁ and V ₂ are compared, and if the wind speed V is outside the wind speed range, a low level determination signal is output, and if it is within the wind speed range, a high level determination signal is output.

The rotation speed discriminator 422 is the rotor 3 of the generator 3.
It determines whether or not the rotation speed N of a is equal to or higher than the rotation speed N _{P at} which power can be generated (hereinafter referred to as the power generation start rotation speed N _P ). The angular velocity ω detected by the angular velocity detector 6 is determined.
(N) is compared with a preset power generation start angular velocity ω _P (N _P ), and if the angular velocity ω is lower than the power generation start angular velocity ω _P , a low level determination signal is output and the power generation start angular velocity ω
If it is _P or more, a high-level discrimination signal is output.

The wind speed discriminator 421 and the rotation speed discriminator 4
The discriminating signal output from 22 is converted into a logical product signal by the AND circuit 426, and the logical product signal is input to the output adjusting circuit 423. The logical product signal, in wind speed V power generation can wind velocity range, and, in determination of whether or not the signal speed N of the rotor 3a is power generation start rotation speed N _P above, V ₁ ≦
If V ≦ V ₂ and N ≧ N _P , a high level determination signal is input to the output adjustment circuit 423, and the wind speed V <V ₁ or V ₂ <
If V and N <N _P , the low level determination signal is input to the output adjustment circuit 423.

The output adjusting circuit 423 adjusts the output of the generator 3. The output adjustment circuit 423 uses the rotor 3a.
Of the DC current command value i _dc ^* with respect to the angular velocity ω of
Current angular velocity ω of the rotor 3a input from
The DC current command value i _dc ^* is output based on the determination signal input from the D circuit 426.

When the rotor angular velocity ω reaches the powering operation start angular velocity ω _O (powering operation start rotation speed N _O ), the above-mentioned function program is executed until the generator 3 reaches the powering operation stop angular velocity ω _E.
Is driven as a motor, and when the rotor angular velocity ω further increases to the power generation start angular velocity ω _P , the regenerative operation of the generator 3 is started. Then, a allows constant velocity ratio operation by the frequency control slip between the rated angular speed omega _C the rotor angular velocity omega is possible power generation of the power generation start angular velocity omega _P and the rated output P1, the rotor angular velocity omega is more the nominal angular velocity omega _C Then, the rated output operation is performed by controlling the pitch angle of the propeller 1b of the wind turbine body 1.

Therefore, the output adjusting circuit 423 instructs the pitch angle changing device 1c to set the propeller 1 when ω <ω _C.
A control value for fixing the pitch angle of b to a predetermined rated pitch angle β _C is output, and when ω _C ≦ ω, the rotor angular velocity ω is maintained at the rated acceleration ω _C in order to keep the output of the generator 3 at the rated output. As described above, the control value of the predetermined pitch angle corresponding to the variation of the rotor angular velocity ω is output.

Further, the output adjusting circuit 423 outputs a direct current command value i _dc ^* for powering the generator 3 to ω _O ≦ ω ≦ ω _E , and ω _P ≦ ω ≦ ω
_{At O} , the DC current command value i _dc ^* for performing the constant peripheral speed ratio operation of the generator 3 is output, and at ω _O ≤ω, the DC current command value for performing the constant output operation of the generator 3 is output. Output i _dc ^* .

In the constant peripheral speed ratio control, the excitation frequency of the converter 41 (that is, the slip frequency of the induction generator 3) according to the wind speed V so that the output coefficient C _P becomes the maximum output coefficient C _PMAX for each wind speed V. The control is based on the following principle.

That is, the output P and the peripheral speed ratio T _SR of the propeller-type wind turbine are expressed by the following equations (1) and (2). When the wind speed V is deleted from both equations, the output P shown in the following equation (3) is obtained.
And a relational expression of the rotation speed N of the wind turbine is obtained.

[0031]

[Equation 1]

[0032]

[Equation 2]

If the pitch angle β of the propeller is constant, the output coefficient C _P becomes maximum at a certain peripheral speed ratio T _SR0 , so the wind speed V
If the rotational speed N of the wind turbine is controlled so that the peripheral speed ratio becomes T _SR0 in accordance with the change of, the output P is always the maximum output P _MAX (= K · C _PMAX · N) at the wind speed V from the above equation (3). _f ³ / T
_SR0 ³ ) can be used.

On the other hand, at a certain pitch angle β, the peripheral speed ratio T _SR0 and the maximum output coefficient C _PMAX are constant values, respectively. Therefore, the relational expression of P _MAX = K · C _PMAX · N _f ³ / T _SR0 ³ More specifically, the maximum output P _MAX for each rotational speed N of the wind turbine is uniquely determined, and the maximum output P _MAX can be calculated as a function of the rotational speed N _f ³ . Therefore, the constant frequency is equivalently controlled by controlling the excitation frequency of the converter 41 so that the output P with respect to the rotational speed N _{f of the} wind turbine, that is, the rotational speed N of the rotor 3a is always the maximum output P _MAX with respect to the rotational speed N. Speed ratio control can be performed.

In the present embodiment, a function of the output current i _dc ^* of the converter 41 corresponding to the maximum output P _MAX with respect to the rotation speed N of the rotor 3a is preset and the angular velocity ω of the rotor 3a of the generator 3 is detected. At the same time, the current output current i _dcf of the generator is detected, and the current control target value i _dc ^* is calculated from the above function based on the above detection result ω. Then, the excitation frequency (synchronous speed) of the generator 3 is adjusted so that there is no deviation between the calculated current control target value i _dc ^* and the detected output current i _dcf, and the angular speed ω (rotation speed N) of the rotor 3a is adjusted. Is controlled to control the constant peripheral speed ratio.

On the other hand, in the constant output control, the pitch is changed according to the change of the rotation speed N so that the rotation speed N of the rotor 3a of the generator 3 is maintained at the rated rotation speed N _C capable of outputting the rated output P1. The propeller 1b of the wind turbine body 1 via the angle changing device 1c
The pitch angle β is controlled.

The PI controller 424 is a signal controller for stabilizing the operation of the feedback system, and is a current detector CT.
The deviation signal Δi _dc ^* (= i _dc ^* -i _dcf ) obtained by negatively feeding back the output current i _dcf of the converter 41 detected by 1 to the DC current command value i _dc ^* is adjusted to the PI operation control signal. It is a thing.

The deviation signal Δi _dc ^* is a signal corresponding to the slip angular velocity, and the PI operation control signal output from the PI controller 424 (hereinafter referred to as the slip angular velocity signal ω _S ) is the torque current generation circuit of the current control circuit 425. On the other hand, the frequency control signal ω1 (= ω−ω) corresponding to the control target value of the excitation frequency of the converter 41 is input from the slip angular velocity signal ω _S and the angular velocity ω of the rotor 3a detected by the angular velocity detector 6 while being input to 425D. _S ) is generated, and the frequency control signal ω1 is generated by the exciting current generation circuit 42 of the current control circuit 425.
Input to 5C.

The current control circuit 425 controls the speed of the generator 3 by vector control, and is a 3-phase / 2-phase converter 4
25A, a phase generator 425B that generates a phase command value θ ^* of a vector control parameter, a magnetizing current generator 425C that generates a magnetizing current command value i _d ^* of the same parameter, and a torque current command value i _q ^* of the same parameter. Vector control PW for generating a gate pulse signal for each switching element of the torque current generator 425D and converter 41
It is composed of an M circuit 425E.

The 3-phase / 2-phase converter 425A is a current detector C.
3-phase generator 3 detected by T2 (u, v, w) conversion in, for example, the excitation current (i _u, i _w) of the u-phase and w-phase of the magnetizing current i _d and a torque current i _q ( Rotational coordinate conversion). 3-phase / 2-phase converter 425A is three-phase excitation currents (i _u, i _w) from orthogonal two-phase currents (i.alpha = (i
_{u + 2i w) / √ (} 3), iβ = i u) is calculated, and further the two-phase currents (i.alpha, i.beta) and the phase command value generated by the phase generator 425B theta ^* and the magnetizing current i _d ( = -Iα ・ si
nθ ^* + iβ · cosθ ^*) and the torque current i _q (= iα · cosθ
^* + Iβ · sin θ ^* ) is calculated.

Further, the phase generator 425B and the magnetizing current generator 425C respectively generate the phase command value θ ^* and the magnetizing current command value i _d ^* based on the frequency control signal ω1, and the torque current generator 425D. Generates the torque current command value i _q ^* based on the slip angular velocity signal ω _S.

The phase command value θ ^* is calculated by the three-phase / two-phase converter 4
25A and the vector control PWM circuit 425E, and the magnetizing current command value i _d ^* and the torque current command value i _q ^* are input ^.
Command command value ^{_{Δi d (= i d * -i}} d) and the torque current of the magnetizing current as a difference by the magnetizing current i _d and a torque current command value i _q calculated in 3-phase / 2-phase converter 425A, respectively It is converted into a value Δi _q (= i _q ^* −i _q ) and input to the vector control PWM circuit 425E.

The vector control PWM circuit 425E controls the voltage command value v in the magnetization axis direction based on the control signals Δi _d and Δi _q.
calculates the _d ^* and the torque-axis voltage command value v _q ^*, the voltage command values v _d ^*, v _q ^* and the phase command value theta ^*
The three-phase voltage command value (V _u , V _v , W _w ) is calculated based on
Furthermore, based on this three-phase voltage command value (V _u , V _v , W _w ), P
A gate pulse signal composed of a WM signal is generated and output to the converter 41.

In the converter 41, the excitation circuit is driven based on the gate pulse signal input from the vector control PWM circuit 425E, and the slip frequency is equivalently controlled to control the output current i _dcf of the generator 3 to the target current value. i
Adjust to _dc ^* (current value corresponding to maximum output).

The inverter control circuit 44 includes an output voltage detector 441 and a PID (Proportional Integral Derivativ).
e) Adjuster 442, system voltage detector 443, phase adjuster 444, multiplier 445 and PWM circuit 446 (P in the figure)
Indicated by WM. ), And properly controls the interconnection between the generator output by the inverter 43 and the electric power system K.

That is, the converter 41 is affected by the generator 3 side, while the inverter 43 is affected by the power system K and the load R, and the power conversion characteristics of both are different.
The output voltage of the converter 43 may increase or decrease due to an error between the output current of the converter 41 and the output current of the inverter 43.
4 is an inverter 4 so that the error of the output current is zero.
3 is controlled to hold the output voltage of the converter 41 at a predetermined voltage V _O.

Further, the inverter control circuit 44 controls the drive of the inverter 43 based on the phase information of the AC power of the power system K, so that the power generated by the generator 3 is effectively synchronized with the power system K. It is regenerated to the power system K.

In the inverter control circuit 44, the output voltage V of the converter 41 detected by the output voltage detector 441 is compared with the DC voltage command value (corresponding to the above predetermined voltage) V _0, and the difference signal ΔV ( = V- _VO )
Is adjusted to the PID operation signal by the PID adjuster 442. The deviation signal ΔV output from the PID controller 442 is the direct current command value i _dc output from the output adjustment circuit 423.
^* Positive feedback to the DC current command value variation in the output voltage of the converter 41 is compensated by i _dc ^* is generated, the DC current command value i _dc ^* is input to the multiplier 445.

On the other hand, the system voltage detector 443 detects the AC voltage of the power system K and the phase adjuster 44
The phase of this AC voltage is detected by 4, and the detection result is input to the multiplier 445.

Then, the multiplier 445 multiplies the DC current command value i _dc ^* by the phase information to generate the current instantaneous command value i ^* synchronized with the power system K, and further, the current instantaneous command value i ^* Inverter 4 detected by detector CT3
The instantaneous value i _ac of the output current of 3 is negatively fed back to generate a control signal Δi (= i ^* -i _ac ) as a difference, and the control signal Δi is input to the PWM circuit 446.

The PWM circuit 446 generates a gate pulse signal composed of a PWM signal based on the control signal Δi, and the gate pulse signal causes the inverter 43 to output the control signal Δ.
Feedback control is performed so that i becomes 0.

Next, the power generation control of the wind turbine generator will be described with reference to the flowchart of FIG.

FIG. 2 is a flow chart showing power generation control from a wind speed of 0 (m / s) to a wind speed at which rated operation is possible.

In the operation standby mode (# 2), the rotation speed determination circuit 422 determines whether or not the rotation speed N of the rotor 3a exceeds the power generation start rotation speed N _P (#
4) When the rotation speed N rises above the power generation start rotation speed N _P (YES in # 4), power generation by the generator 3 is started (#
6), the generator 3 is operated at a constant peripheral speed ratio by the converter control circuit 42 in accordance with a preset function program (function program in the output adjustment circuit 423) (#
8).

In this constant peripheral speed ratio operation, the rotational speed N of the rotor 3a is the rotational speed N _{S at} which the power generation operation of the generator 3 should be stopped.
(<N _P. Hereinafter, referred to as power generation stop rotation speed N _S ) When the rotation speed is reduced to a lower speed (NO in # 10), the power generation operation is stopped and returns to # 2, and the rotation speed N of the rotor 3a is stopped. If it is between the rotation speed N _S and the rated rotation speed N _C (YES in # 10, #
12 is NO), the constant peripheral speed ratio operation is continued (# 8 to # 1).
2 loops).

On the other hand, when the rotation speed N of the rotor 3a rises to the rated rotation speed N _C (YES in # 12), the operation of the generator 3 is switched from the constant peripheral speed ratio operation to the constant output operation (# 1).
4). In this constant output operation, if the rotation speed N is equal to or higher than the rated rotation speed N _C (YES in # 16), the constant output operation of the generator 3 is continued (# 14, # 16 loop), and the rotation speed N is When the speed drops below the rated speed N _C (# 1
(NO in 6), returning to # 8, the operation of the generator 3 is switched from the constant output operation to the constant peripheral speed ratio operation.

On the other hand, in # 4, the rotation speed N is the power generation start rotation speed N.
If the rotation speed is lower than _P (NO in # 4), the rotation speed N of the rotor 3a further determines the rotation speed N _O (<N _S <N _P. called N _O.) whether decreased is determined in the following (# 1
8).

If the rotation speed N of the rotor 3a is lower than the rotor stop rotation speed N _O (NO in # 18), the operation returns to # 2 and the operation is in standby state, and the rotation speed N is the rotor stop rotation speed N _O. If it is above (YES in # 18), the wind speed V further detected by the wind speed detector 5 is a wind speed (V ₁ ≦ V _1).
It is determined whether or not V ≦ V ₂ ) (# 20).

If the wind speed V is not a wind speed at which power generation is possible (V <
V ₁ or V ₂ <V, NO in # 20), the process returns to # 2, the operation standby state is reached, and the wind speed at which power generation is possible (V ₁ ≦ V ≦
V _2, YES at # 20), a power running operation of the generator 3 is started, the rotor 3a is forcibly rotated (# 22).

In the power running operation of the generator 3, the rotation speed N _E of the rotor 3a stops the power running operation N _E (N _O <N _E <
N _S. Hereinafter, the power running operation stop rotation speed N _E is referred to. ) Is continued (# 22, # 24 loop), and the rotor 3
When the rotation speed N of a rise in the power-running operation stop rotational speed N _E (YES at # 24), a power running operation of the generator 3 is stopped (# 26).

It should be noted that the power running operation stop rotation speed N _E is a rotation speed at which the rotation can continue to rise to the power generation start rotation speed Np due to inertia even when the power running operation of the rotor 3a is stopped, and self-starting for power generation. It is a possible rotation speed. The power running stop speed N _E is set in advance based on the configurations of the wind turbine body 1 and the generator 3.

In this flowchart, the generator 3 is rotated at the rotational speed N _E at which continuous rotation is possible, which is lower than the power generation start rotational speed N _P.
The power running operation of FIG. 2 is stopped, but as shown in the flow chart of FIG.
And the step of # 26 are deleted, and the rotation speed N of the rotor 3a is
The power running operation of the generator 3 may be continued until increases to the power generation start rotational speed N _P (see the loop of # 28 in FIG. 3).

In this way, immediately after the power running of the generator 3 starts, the rotation speed N of the rotor 3a decreases due to the decrease in the wind speed V, and the forced start for the power running is repeatedly performed without performing the regenerative operation. It is possible to prevent the unstable driving operation of being disturbed.

Returning to FIG. 2, after stopping the powering operation, the rotor 3
When the rotation speed N of a increases to the power generation start rotation speed N _P (# 3
If YES in 0), the process proceeds to # 6, the regenerative operation of the generator 3 is started, and if the rotation speed N of the rotor 3a does not rise to the power generation start rotation speed N _P (NO in # 30), the process returns to # 2. , Goes into a standby state.

FIG. 4 is a diagram showing the output characteristics of the rotor with respect to the rotational speed of the rotor during the power running operation of the wind turbine generator.

In the figure, the vertical axis represents the output of the rotor 3a, and the horizontal axis represents the rotation speed N of the rotor 3a. The output characteristic indicated by the solid line corresponds to the flow chart shown in FIG. 2, and the output characteristic indicated by the dotted line corresponds to the flow chart shown in FIG. The arrow indicates the direction of change of the rotor speed N. The path at the start of power generation by increasing the wind speed (power generation starts at the speed N _P ) and the path at power generation stop by the wind speed decrease (power stop at the speed N _S). ) Is different because of the hysteresis characteristics of the wind turbine generator.

In the output characteristic shown by the solid line, the wind speed is 0 (m / m /
When the wind speed V increases from (s), the rotation speed N of the rotor 3a of the generator 3 is changed to the rotor stop rotation speed N according to the increase in the wind speed V.
When _O to rise, power operation of the generator 3 is started, the power running operation is continued until the rotational speed N of the rotor 3a is raised to the power running operation stop rotational speed N _E.

In the power running operation, the converter control circuit 42 adjusts the magnetizing current i _d to keep the magnetic flux of the exciting circuit of the generator 3 constant, and the torque current i _q is adjusted to generate the rotor 3a. The torque is held constant, and constant torque control (constant slip control) is performed. Therefore, the rotor output P between the rotational speed N _O and the rotational speed N _E decreases in proportion to the rotor rotational speed N in the negative region.

When the rotational speed N of the rotor 3a rises to the rotational speed N _E for stopping the power running operation due to the power running operation, the power running operation of the generator 3 is stopped and the rotor output P becomes zero.
After that, when the rotation speed N of the rotor 3a rises to the power generation start rotation speed N _P , power generation by the constant peripheral speed ratio operation of the generator 3 is started, and the output of the generator 3 increases as the rotation speed N increases. To do.

On the other hand, when the wind speed V decreases from the wind region where power can be generated, when the rotation speed N of the rotor 3a decreases to the power generation stop rotation speed N _S , the power generation operation of the generator 3 is stopped and the rotor output P is It becomes 0. Then, when the rotation speed N of the rotor 3a decreases to the rotor stop rotation speed N _O , it is determined that the rotation of the rotor 3a has stopped, and the power running operation of the generator 3 is restarted.

When the power running operation is continued after the start of the power running operation until the rotation speed N of the rotor 3a rises to the power generation start rotation speed N _P , the rotor output P is in the negative region as shown by the dotted line. When the rotation speed N of the rotor 3a increases in proportion to N and the rotation speed N of the rotor 3a rises to the power generation start rotation speed N _P , the operation of the generator 3 is switched from the power running operation to the regenerative operation. In addition,
In the control for continuing the powering operation up to the power generation start rotation speed N _P , as shown by the alternate long and short dash line in FIG.
_The torque may be gradually reduced from the rotation speed before _P.

As described above, in the region where the rotation speed N of the rotor 3a is equal to or lower than the power generation start rotation speed N _P , the generator 3 is operated in the power running mode so that the rotor 3a is forcibly driven to rotate. When the rotation speed N of the rotor 3a rises to the power generation start rotation speed N _P , the generator 3 is surely regenerated,
Electric power can be supplied to the power grid K.

FIG. 5 shows a second wind power generator according to the present invention.
It is a block diagram of an Example. The first embodiment is based on the converter 41.
The power running operation of the generator 3 is performed with the preset torque characteristic by controlling the output current of the second embodiment, but the second embodiment has the preset output characteristic by controlling the output power of the converter 41. The power running of the generator 3 is performed.

Therefore, in FIG. 5, the function program of the output adjustment circuit 423 in FIG. 1 is changed to the function program of the DC power command value (target value) p _dc ^* for the angular velocity ω of the rotor 3a, and the current detector CT1 is changed. A converter circuit 427 for converting the output current i _dcf of the converter 41 detected by the above into the output power p _dcf and negatively feeding back the direct current power command value p _dc ^* output from the output adjustment circuit 423, and further converting the current PWM circuit 428 instead of control circuit 425
And a V / F conversion circuit 429 is provided.

In the wind turbine generator shown in FIG. 5, the output power p _dcf of the converter 41 is negatively _fed back to the DC power command value p _dc ^* output from the output adjustment circuit 423, and the output deviation signal Δp _dc ^* (= p _dc ^* −p _dcf ) is obtained, and this deviation signal Δp _dc ^* (corresponding to the slip angular velocity signal ω _S ) is the PI controller 4
At 24, the PI operation control signal is adjusted.

Then, from the PI operation control signal output from the PI adjuster 424 and the angular velocity ω of the rotor 3a detected by the angular velocity detector 6, the frequency control signal ω1 (=
ω−ω _S ) is generated, and the frequency control signal ω1 is PW
It is inputted to the M circuit 428, and at the same time the F / V conversion circuit 4
The voltage control signal V1 ^* (= Kv · ω1) is converted by 29 and input to the PWM circuit 428.

The frequency control signal ω1 and the voltage control signal V1 ^* are signals for controlling the primary frequency and the primary voltage of the generator 3, respectively. The PWM circuit 428 controls the frequency control signal ω1.
Also, a gate pulse signal composed of a PWM signal is generated based on the voltage control signal V1 ^* , and the gate pulse signal is output to the converter 41 to power-operate the generator 3 with a predetermined constant output characteristic.

The wind turbine generator according to the second embodiment also performs power generation control according to the flowcharts shown in FIGS. Therefore, detailed description of the power generation control is omitted here.

FIG. 6 is a diagram showing the output characteristic of the rotor with respect to the rotational speed of the rotor during the power running operation of the wind turbine generator according to the second embodiment.

The wind turbine generator according to the first embodiment controls the output current of the converter 41 so that the generator 3 has a constant torque characteristic.
The rotor output P between the rotational speed N _O and the rotational speed N _E decreased in proportion to the rotor rotational speed N in the negative region (see FIG. 4) because the power running operation was performed in the second embodiment. Since the wind power generator concerned controls the output electric power of converter 41 and carries out the power running operation of generator 3 with a constant output characteristic, as shown in Drawing 6, between rotation speed N _O -rotation speed _NE . The rotor output P has a constant value in the negative region regardless of the rotor rotation speed N.

The output characteristic shown by the dotted line in the figure is for the case where the power running operation is continued until the rotation speed N of the rotor 3a rises to the power generation start rotation speed N _P , and the output characteristic shown by the one-dot chain line is The output is gradually reduced from the rotation speed before the power generation start rotation speed N _P.

When the first embodiment and the second embodiment are compared, in the first embodiment the power generator 3 is driven with a constant torque regardless of the rotor rotation speed N, so compared with the second embodiment. The rotation speed N of the rotor 3a can be increased to the power generation start rotation speed N _P in a short time. On the other hand, the second embodiment has a larger starting torque than the first embodiment, and the starting of the power running operation becomes easier.

FIG. 7 shows a third wind power generator according to the present invention.
It is a block diagram of an Example. FIG. 7 shows the F / V in FIG.
A power running operation control circuit 430 is provided instead of the converter 429, and the power running operation of the generator 3 is performed by controlling the excitation frequency of the converter 41 based on a preset angular acceleration characteristic. .

During power running of the generator 3,
The generation circuit of the frequency control signal ω1 including the PI controller 424 and the conversion circuit 427 is not operated, and the operation control of the converter 41 is performed only by the power running operation control circuit 430 and the PWM circuit 428, and the operation of the generator 3 is performed by the power running. When the operation is switched to the regenerative operation, the generating circuit is operated to perform the constant peripheral speed ratio operation.

The power running control circuit 430 has a function program of the angular acceleration characteristic (ω = K · t) shown by the solid line in FIG. 8, and when the power running is started, the frequency control signal ω1 based on the above function program. ^* (= K · t) and the voltage control signal V1 ^* (= Kv · ω1 ^* ) are generated, and the PWM circuit 428 is generated.
To enter.

The PWM circuit 428 controls the frequency control signal ω.
A gate pulse signal composed of a PWM signal is generated based on 1 ^* and the voltage control signal V1 ^* , and the gate pulse signal is output to the converter 41 to perform the power running operation of the generator 3.

In the angular acceleration characteristic, the acceleration may be constant, but the acceleration may be gradually increased as shown by the dotted line in FIG.

[0088] As described above, in the power running of the generator 3, the angular Since acceleration characteristics so that the rotation drive of the rotor 3a, more quickly rotational speed N of the power generation start rotation speed N _P of the rotor 3a Can be raised to.

[0089]

As described above, according to the present invention,
When the wind speed and the rotation speed of the rotor of the AC generator are detected, and the wind speed is equal to or higher than the wind speed at which power can be generated and the rotation speed of the rotor is equal to or lower than the preset continuous rotation speed, the first and Since the second power conversion means is operated in a power mode to increase the rotational speed of the rotor to at least the self-startable rotational speed for power generation, the AC generator can be reliably started at a low wind speed at which power can be generated. , Regenerative operation can be performed.

Further, since the rotor is rotating at the time of disclosure of the regenerative operation of the AC generator, the friction resistance of the power transmission system is relatively small, the load on the movable parts at the time of starting is reduced, and the durability characteristics are improved. The load on the power generator is reduced.

In the power running operation of the AC generator, the output current of the first power conversion means is controlled to drive the rotor at a constant torque, so that the rotational speed of the rotor can be generated relatively quickly. It can be increased to the number of revolutions.

In the power running operation of the AC generator, the output power of the first power conversion means is controlled to drive the rotor at a constant output, so that the power running operation can be started easily. .

In the power running operation of the AC generator, the excitation frequency of the first power conversion means is controlled on the basis of the preset angular acceleration characteristic so that the rotor is accelerated and driven more quickly. The rotation speed of the rotor can be increased to the rotation speed at which power can be generated.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of a wind turbine generator according to the present invention.

FIG. 2 is a flowchart showing power generation control from a wind speed of 0 (m / s) to a wind speed at which rated operation is possible in the wind turbine generator according to the present invention.

FIG. 3 is a flowchart showing a modified example of power generation control from a wind speed of 0 (m / s) to a wind speed at which rated operation is possible in the wind turbine generator according to the present invention.

FIG. 4 is an output characteristic diagram of the rotor with respect to the rotor rotation speed during the power running operation of the wind turbine generator according to the first embodiment.

FIG. 5 is a configuration diagram of a second embodiment of a wind turbine generator according to the present invention.

FIG. 6 is an output characteristic diagram of the rotor with respect to the rotational speed of the rotor during the power running operation of the wind turbine generator according to the second embodiment.

FIG. 7 is a configuration diagram of a wind turbine generator according to a third embodiment of the present invention.

FIG. 8 is a diagram showing an acceleration characteristic of rotor rotation speed.

FIG. 9 is a characteristic diagram showing rotor output torque with respect to rotor rotation speed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wind turbine main body 2 Speed increaser 3 Generator (alternating current generator) 4 Generation control device 41 Converter (first power conversion means) 42 Converter control circuit (operation control means) 421 Wind speed discriminator (wind speed discrimination means) 422 Rotation speed Discriminator (rotational speed discriminating means) 423 Output adjusting circuit 424 PI regulator 425 Current control circuit 426 AND circuit 427 Conversion circuit (power detection means) 428 PWM circuit 429 F / V conversion circuit 430 Power running operation control circuit (operation control means) 43 inverter (second power conversion means) 44 inverter control circuit 441 output voltage detector 442 PID controller 443 system voltage detector 444 phase adjuster 445 multiplier 446 PWM circuit 45 filter circuit 5 wind speed detector (wind speed detection means) 6 Angular velocity detector (rotation speed detection means) CT1 Current detector (current detection Means) CT2, CT3 current detector K power system

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H02P 21/00 H02P 5/408 C

Claims (4)

[Claims] 1. An alternating current generator driven by the rotational force of a wind turbine; first power conversion means for controlling alternating current power output from said alternating current generator and converting this alternating current power to direct current power. A second power conversion unit that converts the DC power output from the first power conversion unit into AC power having a predetermined frequency and supplies the AC power to the power system, a wind speed detection unit that detects a wind speed, and the AC generator. Rotation speed detection means for detecting the rotation speed of the rotor, wind speed determination means for determining whether or not the wind speed is a wind speed at which power can be generated, and the rotation speed of the rotor is set to a preset continuous rotation speed or less. A rotation speed determination means for determining whether or not the rotation speed is lower, and when the wind speed is equal to or higher than a wind speed at which power can be generated and the rotation speed of the rotor is equal to or lower than the rotation speed at which continuous rotation is possible, the first and second The power conversion means is operated by A wind power generator comprising at least a preset operation control means for forcibly increasing the rotational speed of the rotor to a preset self-startable rotational speed for power generation. 2. The wind turbine generator according to claim 1,
The operation control means includes a current detection means for detecting an output current of the first power conversion means, and the operation control means is based on a preset output current characteristic, the detected output current, and the rotation speed of the rotor. A wind power generator characterized by controlling the output current of a power conversion means to drive the rotor with a constant torque. 3. The wind turbine generator according to claim 1,
The operation control means includes the power detection means for detecting the output power of the first power conversion means, and the operation control means is based on the preset output power characteristics, the detected output power, and the rotation speed of the rotor. A wind power generator characterized by controlling the output power of a power conversion means to drive the rotor at a constant output. 4. The wind turbine generator according to claim 1,
The wind power generator according to claim 1, wherein the operation control means controls the excitation frequency of the first power conversion means based on a preset angular acceleration characteristic to drive the rotor by acceleration.