JP2002233193A - Wind power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wind power generator and a wind power generating method capable of expanding a range of variable speed driving of a windmill, without increasing the capacity of the generator or making significant changes to the facilities or equipment of a power generation system. SOLUTION: The wind power generator comprises a synchronous generator 2 which generates electric power by wind power, a variable speed converter control part 11 which outputs a voltage command for controlling the generated voltage of the synchronous generator 2, a variable speed converter 3 which controls the generated voltage of the synchronous generator 2 based on the voltage command. The variable speed converter control part 11 uses the wind power generator which outputs the voltage command to perform a field- weakening control for the synchronous generator if the generated voltage is equal to or higher than a preset voltage limit value, based on the target value of the generated power and a generated current, and the generated voltage of the generated power generated by the synchronous generator.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a wind turbine generator using a synchronous generator.

[0002]

2. Description of the Related Art In a wind power generator, natural wind is used, but it is difficult to keep the wind constant within a certain range. That is, in the wind power generator, the fluctuation of the wind speed is very large as compared with the fluctuation of the gas flow rate in the thermal power generation or the water flow in the hydroelectric power generation, and the generated power greatly fluctuates. Therefore,
It is necessary to deal with it differently from normal thermal or hydro power generation.

[0003] In a wind power generator, generators usually used include an induction generator and a synchronous generator. Since the synchronous generator rotates at zero slip, it is advantageous in terms of efficiency as compared with the induction generator. In a synchronous generator, the generated power is
It is easy to control because it increases with the rotation speed of the field. However, on the other hand, as the wind speed increases, the rotation speed increases,
As a result, the terminal voltage of the synchronous generator becomes very high.
Then, the operation limit is set by the voltage limit value of the synchronous generator. Therefore, there is an upper limit to the wind speed at which power can be generated, and a wind having a high energy and a high wind speed cannot be used effectively. Even if it is considered to operate at the full operating limit, it is not preferable for maintenance and safety. Therefore, new countermeasures are required in that case. Further, in a wind power generator, generated power fluctuates rapidly due to abrupt fluctuations in wind speed. In performing grid connection,
A sudden change in the power generation voltage or power generation frequency accompanying this fluctuation is also a problem, and it is necessary to suppress it.

[0004] As a method of responding to the fluctuation of the rotation speed and suppressing the rapid fluctuation of the electric power, there is a method of controlling the pitch angle of the blade of the wind turbine. This is a method of controlling the easiness of rotation of the windmill with respect to the wind to suppress the fluctuation of the rotation speed within a certain range. In this case, since a large blade is driven, the response is not high. Further, it is necessary to prepare another means in order to effectively use the high-speed wind having large energy. For existing wind power facilities that do not use this technology, the cost and effort of remodeling work are increased.

As another method, it is conceivable to design the generator such that the terminal voltage is equal to or lower than the voltage limit value even at the predicted maximum rotation speed. In that case, since the maximum rotation speed is increased, a wind having a high energy and a high wind speed can be effectively used. In addition, when the wind power is strong, the generated power is stored, and when the wind power is weak, the stored power is discharged.
It can be suppressed to a certain range without a sudden change. However, since the current of the generator increases, it is necessary to take measures such as enlarging the generator and the converter. In addition, since the existing wind power generation equipment is a major change, the cost and labor for the remodeling work are increased.

As a technique for widening the range of rotation speed,
In the field of electric motors (not generators), there are several reports on control methods for variable speed drive of synchronous motors (eg, "Basics and Application of AC Motor Variable Speed Drives", Corona, edited by the Institute of Electrical Engineers of Japan). One of them is to control a field current of a synchronous motor. By controlling the DC input voltage (power supply) and the field current, even if the DC input voltage is maximized, the field current is reduced to reduce the field magnetic flux. Can be operated (field weakening control).

As another electric motor, there are some reports on variable speed control of a permanent magnet synchronous motor (hereinafter, referred to as a “PM motor”) that cannot control a field current (for example, “The Latest Technology of Electric Vehicles”). Ohmsha). In i _{d =} 0 control used in conventional PM motor has proposed a controllable operating method in high-speed operation is wide, including the range of rotation of the synchronous motor which can not be controlled. That is, a wide-range variable-speed operation is enabled by introducing maximum torque control during low-speed operation and field-weakening control during high-speed operation.

[0008] Here, _i d = 0 control in the PM motor, the maximum torque control, weakening briefly described field control. The voltage equation and the torque of the permanent magnet synchronous motor expressed on the dq coordinate axes are expressed by Expressions 1 and 2.

(Equation 1)

(Equation 2)Where v_d, V_q: D, armature voltage of q-axis component, R:
Armature resistance for one phase, L _d, L_q: D, q axis armature self
Inductance, ω: rotational speed of the field, s: d / dt,
i_d, I_q: D, q-axis armature current, φ_a: Permanent magnet
Armature interlinkage magnetic flux due to stone field, p: number of magnetic pairs.

[0009] From Equation 2, in the electric motor of L d ₌ L _q become field magnetic type (cylindrical machine field is cylindrical), the torque is determined only by the i _q, the current i _d of d-axis component contribution do not do. Therefore, for high efficiency operation, _id =
0 is desirable. This is _id = 0 control, which is the most common control method for a permanent magnet synchronous motor. On the other hand, in a field type motor (a salient pole machine whose field is a salient pole) in which L _d ≠ L _q , the reluctance torque ((p / 2) ｛(L _d −L _q ) · _id ·
_iq }) remain. Therefore, the reluctance torque is effectively used, and control is performed so as to obtain the maximum torque with the same current. This is called maximum torque control. In that case, the formula which represents the current i _d of d-axis component of the permanent magnet synchronous motor is several 3.

(Equation 3)

On the other hand, the terminal voltage of the permanent magnet synchronous motor is
According to Equation 1, the rotation speed increases with the rotation speed ω. In this case, field weakening control is generally used to extend the speed control range. However, in the case of a permanent magnet synchronous motor, the field cannot be controlled. Therefore, by using the demagnetizing effect due to the d-axis armature reaction to weaken the field magnetic flux, the same effect as the weak field control can be obtained. For field weakening, the number equation representative of the current i _d of d-axis component 4
become that way.

(Equation 4) Here, V _0m : V _am -RI _am , I _am : current limit value of the armature, and V _am : terminal voltage limit value.

However, the variable speed control in the synchronous machine described above is performed only in the electric motor, and has not been considered in the field of the generator. In particular, there are not many control technologies that can increase the range of rotational speeds when it is necessary to support a very wide range of rotational speeds, such as in the field of wind power generation.
A method of controlling the pitch angle and a method of coping with the peripheral equipment and devices are mainly employed. Therefore, there is a strong demand for a low-cost, easy-to-introduce technology that can extend the windmill variable-speed operation range to the high-speed rotation side only by changing the control method.

[0012]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a wind power generator and a wind power generation method capable of expanding a variable speed operation range of a wind turbine without increasing the capacity of the generator. is there.

Another object of the present invention is to provide a wind power generator and a wind power generation method capable of expanding a variable speed operation range of a wind turbine without making significant changes to facilities and equipment related to a power generation system. It is.

Still another object of the present invention is to provide a wind power generator and a wind power generation method capable of expanding a wind turbine variable speed operation range only by changing a control method.

Still another object of the present invention is to provide a wind power generation device and a wind power generation method which use wind power with little waste and have high efficiency.

[0016]

Means for Solving the Problems In the section of the means for solving the problems, the figure numbers and reference numerals are written to show the correspondence between the claims and the embodiments of the invention. It should not be used to interpret the claims.

Therefore, in order to solve the above-mentioned problems, a wind power generator according to the present invention comprises a synchronous generator (FIGS. 1 and 2) for generating electric power by wind power and a voltage generated by the synchronous generator (FIGS. 1 and 2). A variable speed converter control unit (FIGS. 1 and 11) for outputting a voltage command for controlling the voltage command;
Variable speed converter for controlling the generated voltage (FIGS. 1, 3)
And

Further, in the wind power generator according to the present invention, the synchronous generator (FIGS. 1 and 2) uses a permanent magnet (FIGS.
Using 2), the permanent magnet (FIG. 3, 102) is embedded in the field core (FIG. 3, 101).

Further, in the wind turbine generator according to the present invention, in the variable speed converter control section (FIGS. 1 and 11), when the immediately preceding voltage command is equal to or more than a preset voltage limit value, the synchronous generator ( The voltage command is output so as to reduce the field magnetic flux shown in FIGS.

Further, in the wind turbine generator of the present invention, in the variable speed converter control section (FIG. 1, 11), when the immediately preceding voltage command is less than the voltage limit value, the synchronous generator (FIG. 1, FIG. The voltage command is output so that the torque of 2) is maximized.

Further, in the wind power generator according to the present invention, the variable speed converter control section (FIGS. 1 and 11) may be arranged so that the synchronous generator (FIGS. 1 and 2) has a predetermined field rotation speed. If the value is equal to or more than the value, the voltage command is output so as to reduce the field magnetic flux of the synchronous generator (FIGS. 1 and 2). The voltage command is output so that the torque of the generator (FIGS. 1 and 2) is maximized.

In order to solve the above-mentioned problems, a wind power generation method according to the present invention uses a target value of power generated by a synchronous generator (FIGS. 1 and 2) and a power generated by the synchronous generator (FIGS. 1 and 2). A step of outputting a voltage command for controlling the generated power based on the current and the voltage of the power supply, and a step of controlling the generated power based on the voltage command.

Also, in the wind power generation method according to the present invention, the step of issuing the voltage command is performed when the immediately preceding voltage command is smaller than a preset reference value. The voltage command is output such that the torque is maximized. If the immediately preceding voltage command is equal to or greater than the reference value, the voltage command is output so as to reduce the field magnetic flux of the synchronous generator.

Further, in the wind power generation method according to the present invention, the step of outputting the voltage command is performed by the synchronous generator (FIG. 1,
When the field rotation speed of 2) is less than a preset rotation speed limit value, the voltage command is output so that the torque of the synchronous generator (FIGS. 1 and 2) is maximized, and the field rotation is performed. When the speed is equal to or higher than the rotation speed limit value, the voltage command is output so as to reduce the field magnetic flux of the synchronous generator (FIGS. 1 and 2).

Further, a program for executing the above-described wind power generation method is also a solution of the present invention.

In the present invention, a current command is a current value that is a target value for control, and a voltage command is
The power value is a voltage value serving as a control target value, and the power command is a power value serving as a control target value.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wind turbine generator according to the present invention will be described below with reference to FIGS. 1, 2 and 3 of the accompanying drawings. In the present embodiment, a wind power generator having a permanent magnet synchronous generator using wind power will be described as an example, but the present invention is also applied to a power generator having a synchronous generator using energy of a variable speed medium. It is possible.

The conventional wind power generator, which mainly responds to the fluctuation of the wind power by adding equipment having various functions, is changed according to the present invention by a slight change of the existing wind power generator. Therefore, it is possible to greatly expand the variable speed operation range of the wind turbine. That is, by introducing the concept of field-weakening control, which has not been used in wind power generation equipment at all, into wind power generation for the first time, it becomes possible to effectively use wind power in a wide range of wind power.

FIG. 1 is a block diagram showing an embodiment of the present invention, in which a wind turbine 1, a synchronous generator 2, a variable speed converter 3,
It comprises a variable speed converter control unit 11 and an encoder 16. The variable speed converter controller 11 includes a power detector 4, a speed / magnetic pole position detector 5, a dq phase converter, a torque calculator 7, a PID controller 8, a current controller 9, a three phase converter 10,
A d-axis component current calculator 12 is provided. FIG. 2 is a diagram showing a connection from the wind turbine 1 to the system coordination, which is connected to the variable speed converter 3 in FIG. 1 to provide a DC link unit 13, a system coordination inverter 14, a system coordination inverter control unit 15
Consists of

The wind turbine 1 is rotated by wind power, and power is generated in the synchronous generator 2. The generated power is controlled by the variable speed converter control unit 11 via the variable speed converter 3. The generated power is converted into DC _vdc in the variable-speed converter 3, then converted into a desired frequency and voltage by the system-coupling inverter 14, and is passed to the power system. The frequency and voltage are controlled by the system-linked inverter control unit 1.
5 through the system linking inverter 14.

Regarding the control of the generated power, the variable speed converter
Data control unit 11 receives an external power command P^*Corresponding to
And the generated power P (v_u, V_v, I_u,
i_v) To P ^*By adjusting it to match
U. That is, the power command (P^*) And the current generated power
A voltage command (voltage v) for controlling the generator based on P_u
^*, V _v ^*, V_w ^*) To the variable speed converter 3
Variable speed converter 3 based on the voltage command.
This is performed by controlling the period generator 2. At that time, usually
Performs maximum torque control with an emphasis on efficiency, but
When the magnetic pole rotation speed of the generator becomes very high
Is switched to field weakening control and the voltage between the terminals of the generator is
Control so that the wind turbine variable speed operation range can be widened.
U. This will be described in detail below.

In FIG. 1, a wind turbine 1 includes a wind turbine blade,
It is a windmill including a rotor shaft and the like. It is connected to the field of the synchronous generator 2 via a power transmission shaft, a gearbox, and the like. Windmill 1
Has a pitch control function that can control the pitch angle of the blade.

The encoder 16 is a speed sensor for detecting the rotation speed and the position of the magnetic pole (field) attached to the synchronous generator 2. The detected signal is output to the speed / magnetic pole position detector 5, where the position (θ) and the rotational speed (ω _r ) are obtained.

The synchronous generator 2 has the same structure as a rotating field type permanent magnet.
It is a period generator. The permanent magnet type is selected for rotation
The structure of the generator, including the field, can be used for other types of synchronous generators.
This is because the comparison becomes simple. In this embodiment,
The permanent magnet for the field uses an embedded magnet type permanent magnet.
You. The choice of the embedded magnet type is for maximum torque control and
This is for performing field weakening control. In other words, those
As a prerequisite, the reluctance torque (Equation 2 right side
2) must occur, for which L _d≠ L
_qIt is necessary to be.

FIG. 3 shows a cross section of a synchronous generator using an embedded magnet type permanent magnet. Field core 101, permanent magnet 102,
An armature winding 103 and an armature core 104 are provided. Outside the cylindrical field core 101, there is a cylindrical armature core 104 concentric with the field core 101. Permanent magnet 102
Has a rectangular parallelepiped shape, and is embedded radially in the radial direction of the field iron core 101 so that the permanent magnet 102 is exposed on the outer peripheral side of the field iron core 101. Adjacent permanent magnets 102 have the same polarity. In the armature core 104, a groove (slot) accommodating the armature winding 103 on the inner peripheral side exists radially in the radial direction of the armature core 104 and halfway through the armature core 104. The rotation of the field permanent magnet 102 causes the armature winding 10 to rotate.
3, an induced electromotive force is generated, and power is generated. (Note that FIG. 3 refers to a diagram of a permanent magnet synchronous motor described in “Basics and Application of AC Motor Variable Speed Drive” (edited by the Institute of Electrical Engineers of Japan, Corona Co., p. 142). The reason is that the generator and the synchronous motor in the above-mentioned drawings have the same basic structure, although there is a difference between the generator and the motor.)

The variable speed converter 3 is generated by the synchronous generator 2
AC power (voltage: v_u, V _v, V_w, Current: i
_u, I_v, I_w) Is a converter that converts to DC power
is there. The DC power is supplied to the system-linking inverter (
2, 14). Also, the variable speed converter 3
Voltage command of variable speed converter control unit 11 (described later)
v_u ^*, V_v ^*And v_w ^*And the power generation of the synchronous generator 2
Control the voltage.

The power detection unit 4, the voltage from the AC power generated by the synchronous generator 2 v _u and v _v, by detecting the current i _u and i _v, the generated power P at the current time on the basis of the value calculate.

The speed / magnetic pole position detector 5 is a synchronous generator 2
Based on the signal from the encoder 16 attached to, obtained by calculating the rotational speed omega _r of the magnetic pole obtained by differentiating the magnetic pole position theta (phase) and the magnetic pole position at the present time. It is also possible to estimate the magnetic pole position θ and the rotational speed omega _r not fitted with a position detector to the synchronous generator 2.

The dq-phase converter 6, a current i _u and i _v of power at the moment that is generated by the synchronous generator 2, the magnetic pole position θ
Into a current i _d and i _q of d-axis and q-axis component in the rotating coordinates (d-q axes) system used.

The torque calculating section 7 compares the current generated power P detected by the power detecting section 4 with a target value (power command) P ^{* of the} generated power instructed from outside, and determines a deviation Δ
Calculate P. Then, into a shift ΔT of the torque with the rotational speed omega _r of the magnetic pole of power deviation ΔP of.

The PID control unit 8 controls the current i of the q-axis component for eliminating the torque deviation ΔT calculated by the torque calculation unit 7.
The value of _q ^* is calculated and output as a new q-axis component current (q-axis component current command). At the same time, the current i _q of the q-axis component
^* Is output to the d-axis component current calculator 12.

The current controller 9 converts the current by the dq phase converter 6
The current i of the d-axis and q-axis components_dAnd i_q, D
The current of the d-axis component calculated by the axis component current calculation unit 12 (described later)
Flow i _d ^*(Current command), q-axis calculated by PID control unit 8
Component current i_q ^*From (current command), a new d-axis and q
Axial component voltage v_d ^*And v_q ^*And determine the voltage command.
Output.

The three-phase converter 10 is determined by the current controller 9.
Voltage d-axis and q-axis component voltage v_d ^*as well as
v_q ^*Using the magnetic pole position θ, the three-phase (uvw) axis
Convert to coordinate system (v_u ^*, V_v ^*, V_w ^*) And variable speed
Output to inverter 3. At the same time, the d-axis component current calculation unit 1
2, a new voltage V (= ((v_d ^*)²+
(V_q ^*) ²)^0.5) Is output.

The d-axis component current calculator 12 is a three-phase converter 1
It is determined whether the new voltage V output from 0 is equal to or greater than a preset voltage limit value V _am, a current _id ^* of the d-axis component is determined based on the result, and the current control unit 9 sends the current _id ^* to the current control unit 9. Output the value.

The DC link unit connects the variable speed converter 3 for transmitting DC power and the system-linked inverter 14. In addition, system-linked inverter 14 sends the DC power transmitted from variable speed converter 3 to the power system at a desired voltage and frequency. At this time, based on the value of the voltage _vdc of the DC power and the feedback of the voltage and frequency of the power in the power system, the system-coupling inverter control unit 15 controls the power flowing to the power system via the system-coupling inverter 14. Voltage and frequency.

Next, the operation of the embodiment of the wind turbine generator according to the present invention will be described with reference to FIGS.

When the wind turbine 1 is rotated by wind power, the field, which is an embedded magnet type permanent magnet, in the synchronous generator 2 is rotated, and electric power is generated. The AC power (v _u , v _v , i _u , _iv ) generated by the synchronous generator 2 is supplied to the variable speed converter 3.
Is converted into DC power at the
Sent to Then, there, it is converted into AC power having a predetermined frequency and voltage, and is passed to the power system. On the other hand, power generation is controlled as follows. First, the variable-speed converter control unit 11 detects the characteristics of the power command P ^* from the outside and the power P generated at the present time, and generates a current command based on them. Next, the current command is converted into a voltage command. Then, the power generation is controlled by controlling the variable speed converter 3 by the voltage command. This will be described in detail below.

First, the generation of the current command will be described.
In the variable speed converter control unit 11, the voltages v _u and v _{v of} the power generated at the present time, and the currents i _u and i
_The power detection unit 6 calculates the power P generated at this time from _v . On the other hand, the output of the encoder 16, the magnetic pole position θ and the rotational speed omega _r of the magnetic pole (field) at the present time, determined by calculating a rate-pole position detector 5.

The torque calculator 7 receives a power command P ^* (target value of power) from the outside. Then, a deviation ΔP between the current generated power P calculated by the power detection unit 4 and the power command P ^* is obtained, and the deviation ΔP is calculated by the speed / magnetic pole position detection unit 5 to obtain the rotation speed ω _r of the magnetic pole. To convert it into a torque deviation ΔT. That is, ΔT = (P−P ^* ) / ω
_r . The reason for calculating the torque deviation ΔT is that the control of the synchronous generator 2 is performed by torque control. In order to correct the torque (= adjust the generated power to the power command P ^* ) based on the torque deviation ΔT obtained in this way, first, in the PID control unit 8, a new q-axis component A current _iq ^* (q-axis component current command) is obtained. This value is output to the current controller 9 and the d-axis component current calculator 12.

On the other hand, in response to the input of the current _iq ^* of the q-axis component and the value of the previous (immediately before) voltage command V ′ (described later) output from the three-phase converter 10, the d-axis The component current calculation unit 12 calculates a new d-axis component current _id ^* (d-axis component current command). At this time, according to one of the following two types of control, d is set according to the value of the previous voltage command V ′.
The axis component current command _id ^* is determined.

The previous voltage command V ′ is less than the voltage limit value V _am (V ′ <
V _am ), the maximum torque control is performed on the synchronous generator 2. That is, the generated voltage V ′ is not high (= the rotation speed of the wind turbine 1 is low, so the rotation speed ω _r of the synchronous generator is
This is because there is no hindrance to the power generation system, and the operation can be performed with an emphasis on efficiency. In the synchronous generator 2, when the field is an embedded magnet type, a reluctance torque is generated depending on the phase even if the current value is the same. Therefore, if this reluctance torque is used, it is possible to control so that the torque is maximized with the same current (maximum torque control). The expression representing the current _id ^* of the d-axis component at that time is as shown in Expression 5.

(Equation 5) Here, φ _a : phase of the terminal current, L _d , L _q : d, q-axis armature self-inductance. By the control using this current, the torque increases and the terminal voltage decreases with the same current in the synchronous generator 2, so that the efficiency and the power factor can be improved, and high-efficiency operation is achieved. In addition, Equation 5
Although there is a difference between a generator and an electric motor, they are basically the same as the above equation (3) because they are the same permanent magnet type synchronous machine.

On the other hand, the previous voltage command V ′ is the voltage limit value V of the generator, which is the upper limit value of the terminal voltage of the synchronous generator 2.
_{If it is not} less than _am (V ′ ≧ V _am ), field weakening control is performed on the synchronous generator 2. It is for the following reasons. As the rotation speed of the wind turbine 1 increases, the rotation speed ω _r of the field of the synchronous generator 2 also increases. Then, the terminal voltage of the synchronous generator 2 with it reaches the operating limit by the voltage limit value V _am. Therefore, in order to extend the constant output operation range to a higher speed rotation range, the synchronous generator 2 is set to the voltage limit value V _am
It is necessary to control the following. As a countermeasure, by performing control so as to reduce the field magnetic flux when the rotation speed ω _r rises above a certain value, it is possible to suppress the voltage rise (field weakening control). In this embodiment, since the permanent magnet is used as the field, the field cannot be directly weakened. By doing so, a similar effect can be obtained. This is also called field weakening control. In the case of the field of interior permanent magnet, since the positive reluctance torque is generated by flowing a negative i _d, i _q for generating the same shaft torque is reduced, reducing the effective terminal voltage I can do it. The expression representing the current _id ^* of the d-axis component at that time is as shown in Expression 6.

(Equation 6) Here, ω: rotation speed of the magnetic pole, V _0m : V _am -RI
_am , R: armature resistance for one phase, I _am : current limit value of the armature. With this control, the terminal voltage does not increase with an increase in the rotation speed of the magnetic pole, and operation at a high rotation speed becomes possible. Equation (6) is basically the same as Equation (4) given above because there is a difference between the generator and the motor, but the same permanent magnet type synchronous machine.

[0053] Figure 4, a constant rotational speed in the embedded magnet type permanent magnet synchronous generator omega, in the operating state of the constant torque T, in the case of controlling the d-axis current i _d is the current of the d-axis component Show characteristics. The armature current I _a (=
(( _Id ² + _iq ² ) / 3) ^{0. 5),} taking the q-axis current i _q is the current of the q-axis component, the right-hand y-axis, the terminal voltage V
taking ^{_{a (= (v d 2 +}} v q 2) 0.5). x-axis is the d-axis current i _d is the current of the d-axis component. The top curve on the graph is I _a, 2-th curve is the i _q, bottom curve is V _a. Control is _id = 0
The control is a maximum torque control, and the control is a field weakening control. Terminal voltage Va, the magnitude of the d-axis current | reduced by demagnetization is armature reaction as increases _| i d. Accordingly, in the case of if now, the upper limit value of the terminal voltage when the V _am, the magnitude of the d-axis current than the d-axis current i _d at position | i d _| by increasing the terminal voltage V _a It is possible to operate under the condition of <V _am . Also, speed, when increased than in the case of FIG. 4 is a form of grab showing a V _a is shifted to the overall upward. Even in this _{case, V} a _<V
It can be seen that a i _d may be increased so that the _am. (Note that FIG. 4 is a diagram showing a "control method suitable for an embedded magnet structure PM motor" (IEEE Semiconductor Power Conversion Study Group, 19
92, pp. 45-53) with reference to the drawings of the permanent magnet synchronous motor. This is because the synchronous generator actually used in wind power generation and the synchronous motor in the above-described drawing have the same basic characteristics, although there are differences between the generator and the motor. )

As described above, the current commands _id ^* and i
_q ^* is determined. These current commands are converted into voltage commands by a process described below and output to the variable speed converter 3 to control the synchronous generator 2.

The process of converting a current command into a voltage command is as follows. First, in the dq-phase converter 6, on the basis of the magnetic pole position θ at the present time, the by power currents i _u and i _v power at present, d-axis at the moment in a rotating coordinate (dq axes) system and The currents are converted into q-axis component currents _id and _iq , and output to the current control unit 9. In the current control unit 9,
With reference to current _{i d} and _{i q} of d-axis and q-axis components of the moment, q-axis component obtained by the PID controller 8 current command _i ^{q *}
And d-axis component current command _id ^* calculated by the d-axis component current calculation unit 12 is proportionally and integratedly calculated to obtain d.
It is converted into an axis component voltage command v _d ^* and a q-axis component voltage command v _q ^* .

The three-phase converter 10 outputs a d-axis component voltage command v _d
^{* And the} q-axis component voltage command v _q ^* are converted into a three-phase (uvw) axis system based on the current magnetic pole position θ, and the voltage commands v _u ^* , v _v ^*, and v _w ^*. Is output to the variable speed converter 3. Further, the voltage _V ⁼ to be used to determine the control method ^{_{((v d *) 2 +}} (v q *) 2) outputs ^0.5 (aforementioned V ') to the d-axis component current calculation unit 12.

The variable speed converter 3 receives the voltage commands v _u ^* , v _u from the three-phase converter 10 of the variable speed converter controller 11.
_v In response to ^* and v _w ^*, to control the voltage of the electric power generated by the alternator 2. Since the voltage command is a voltage determined based on the maximum torque control method or the field weakening control method in the variable speed converter control unit 11, even the operation of the synchronous generator 2 is based on the maximum torque control method or the field weakening control method. Can operate.

That is, when the previous voltage command V 'is smaller than the voltage limit value _Vam which is the upper limit value of the voltage between the terminals of the synchronous generator 2, the maximum torque control is performed to improve the efficiency and the power factor. Efficiency-oriented operation is possible. Also,
When the immediately preceding voltage command V ′ is equal to or higher than the voltage limit value V _am that is the upper limit value of the voltage between the terminals of the synchronous generator 2, the field weakening control is performed. The terminal voltage can be suppressed to _Vam or less even when the rotation speed ω of the field pole increases. Therefore, without increasing the capacity of the generator and with minor changes in equipment,
Operation at a high rotation speed becomes possible, and the variable speed operation range of the wind turbine can be expanded.

With the wind power generator combining the maximum torque control and the field-weakening control according to the present invention, the rotation speed of the generator is limited to the rated rotation speed, which has been conventionally limited to the rated rotation speed. It is now possible to extend the range of rotation speeds beyond the speed.

In the present embodiment, the control method between the maximum torque control and the field weakening control is changed based on the magnitude relation between the voltage limit value _Vam and the voltage command V 'immediately before the generated voltage. The above control can be performed based on the magnitude relationship between the limit value V _am and the actual generated voltage immediately before the generated voltage. In this case, the d-axis component current calculation unit 12 tells the d-axis component current calculation unit 12 not the immediately preceding voltage command V 'but the immediately preceding actual voltage value V "
(Calculated from v _u and v _v ).

The control method between the maximum torque control and the field-weakening control is changed by providing a rotation speed limit value ω _am to the value of the rotation speed ω _r of the field pole, and determining the magnitude relationship between ω _r and ω _am. It is also possible to perform control based on. In that case, instead of the immediately preceding voltage command V ′, the immediately preceding actual rotation speed ω of the field magnetic pole is input to the d-axis component current calculator 12. Also, instead of the voltage limit value V _am , a rotation speed limit value ω _am is set.

The present invention is also applicable to existing synchronous generators.
Basically, it can be dealt with only by improving the variable speed converter control unit. In addition, it is possible to cope only by changing the control program. As a result, it is possible to expand the variable speed operation range of the wind without changing the generator and the peripheral equipment and devices.

In this embodiment, a permanent magnet synchronous generator is used as a synchronous generator. However, the present invention can be applied to a wind power generator using another type of synchronous generator that does not use a permanent magnet for the field. . In this case, the maximum torque control and the weak field control can be performed by changing the exciting current of the field. That is, even in such a case, it is possible to perform the field weakening control by reducing the field magnetic flux.

[0064]

According to the present invention, it is possible to extend the range of variable speed operation of the wind turbine without increasing the capacity of the generator.

Further, according to the present invention, it is possible to extend the variable speed operation range of the wind turbine without making significant changes to the facilities and equipment of the power generation system.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram schematically showing an embodiment of a wind turbine power generation device according to the present invention.

FIG. 3 is a cross-sectional view of a wind turbine generator according to the present invention.

FIG. 4 is a graph showing various characteristics of the wind turbine generator according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 wind turbine 2 synchronous generator 3 variable speed converter 4 power detector 5 speed / magnetic pole position detector 6 dq phase converter 7 torque calculator 8 PID controller 9 current controller 10 three phase converter 11 variable speed converter controller 12 d-axis component current calculation unit 13 DC link unit 14 System-linked inverter 15 System-linked inverter control unit 16 Encoder 101 Field core 102 Permanent magnet 103 Armature winding 104 Electric private core

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) HB03 HB20 JA12 JA13 JA14 5H621 AA03 BB10 HH01

Claims (9)

[Claims] A synchronous generator that generates power by wind power; a variable-speed converter control unit that outputs a voltage command for controlling a generated voltage of the synchronous generator; and a generator that converts the generated voltage based on the voltage command. And a variable speed converter to be controlled. 2. The wind power generator according to claim 1, wherein the synchronous generator uses a permanent magnet as a field and embeds the permanent magnet inside a field core. 3. The variable speed converter control section outputs the voltage command to reduce the field magnetic flux of the synchronous generator when the immediately preceding voltage command is equal to or greater than a preset voltage limit value. The wind power generator according to claim 1. 4. The variable speed converter control section outputs the voltage command so that the torque of the synchronous generator becomes maximum when the immediately preceding voltage command is less than the voltage limit value. A wind power generator as described. 5. The variable-speed converter control section, wherein when the field rotation speed of the synchronous generator is equal to or higher than a preset rotation speed limit value, the variable-speed converter control section reduces the field magnetic flux of the synchronous generator. Outputting a voltage command, when the field rotation speed is less than the rotation speed limit value,
The wind power generator according to claim 1 or 2, wherein the voltage command is output so that the torque of the synchronous generator is maximized. 6. A step of outputting a voltage command for controlling the generated power based on a target value of the generated power of the synchronous generator and a current and a voltage of the power generated by the synchronous generator; Performing the control of the generated power based on a voltage command. 7. The step of outputting the voltage command includes, when the immediately preceding voltage command is smaller than a preset reference value, outputting the voltage command such that the torque of the synchronous generator becomes maximum. The wind power generation method according to claim 6, wherein when the immediately preceding voltage command is equal to or more than the reference value, the voltage command is output so as to reduce a field magnetic flux of the synchronous generator. 8. The step of outputting the voltage command is performed such that the torque of the synchronous generator is maximized when the field rotational speed of the synchronous generator is less than a preset rotational speed limit value. Output a voltage command, and when the field rotation speed is equal to or higher than the rotation speed limit value,
The wind power generation method according to claim 6, wherein the voltage command is output so as to reduce a field magnetic flux of the synchronous generator. 9. A program for executing the wind power generation method according to claim 6. Description: