JPS62123995A - Wind power-generator - Google Patents

Abstract

PURPOSE:To acquire energy effectively by conducting variable speed control, through which a wind-mill is operated by the number of revolution corresponding to inputs, in an operation region up to the rated number of revolution from the starting of the wind-mill. CONSTITUTION:With a wind-mill 1 driving an induction machine 2, the pitch angle of a blade is kept constant up to the rated number of revolution, and the pitch angle is controlled so that the number of revolution of the wind-mill reaches rated one in an operation region of the rated number of revolution or more. A comparator 32 transmits a deviation between an output command signal PREF corresponding to the number of revolution N of the wind-mill 1 and an output signal P over a compensation circuit 33. A deviation between a signal obtained by F/V converting the number of revolution N and an output from the compensation circuit 33 is inputted to an exciting-frequency command circuit 36, and the circuit 36 transmits an exciting-frequency command over a converter 30 so that the ratio of generator voltage/operation frequency is kept constant up to the rated number of revolution and so that generator voltage is kept constant at the rated number of revolution or more.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a wind turbine that converts wind energy into shaft power,
Regarding wind power generation equipment using a power-to-power converter that converts this shaft power into electric power, it is used as a power supply device in areas without power supply.
It is also suitable for use as a hybrid power generator with a diesel power generator on remote islands for the purpose of energy conservation, and as a power generator for peak cut in grid connection.

(Prior Art) Conventionally, a synchronous machine, a DC machine, an induction machine, or the like has been used in a wind power generator as a means for converting shaft power of a wind turbine into electric power (power generation 'gM).

However, in general, when using a synchronous machine or a DC machine, the wind turbine blades do not move in the main operating range from the rated wind speed at which the wind turbine's rated output is obtained to the power generation stop speed 1@ at which the wind turbine operation is stopped and power generation is stopped. The pidge control provides constant rotation speed control. For this reason, as will be explained later, the output characteristics that can generate the maximum efficiency of the wind turbine are determined by the wind speed relative to the circumferential speed of the wind turbine.
It was not possible to operate with a constant circumferential speed ratio, and it could not be said that energy was being acquired effectively. Moreover, as mentioned above, constant rotation speed control operation is subject to large torque fluctuations due to sudden changes in wind conditions, and in order to withstand this, the structure and materials must be of uniform quality, which increases costs. It was also the cause.

On the other hand, many of those using induction motors are operated by being connected to the existing power system, and those that use wind speed as the operation control means are common. In this case, since the generator and the wind speed are measured at different points, it becomes difficult to control high viscosity, and sometimes a situation may occur where the induction motor does not operate as a generator but as an electric motor. In order to connect directly to the grid, it will operate at around 50/60Hz,
This resulted in a situation equivalent to constant rotation speed control, and had the same problems as described above.

Furthermore, since average wind speeds are generally low, it has been desired that wind power generators be configured to be able to generate power effectively in a low wind speed range.

(Object of the Invention) The present invention has been made in view of the above problems, and includes setting the pitch angle of the wind turbine blades to a predetermined state according to the wind turbine rotation speed, and
By performing variable speed control that operates the wind turbine at a rotation speed according to the input, it absorbs torque fluctuations caused by sudden changes in wind conditions, suppresses increases in costs in terms of structure and materials, and effectively generates electricity at low wind speeds. It is possible to regenerate a large amount of energy at low cost, and by using wind turbine rotation speed information instead of wind speed information for control and operating the wind turbine with efficient output characteristics, it is possible to achieve a highly accurate constant circumferential speed ratio. It is an object of the present invention to provide a wind power generation device that can be controlled in a controlled manner, and can effectively obtain energy and improve reliability.

(Structure of the Invention) The present invention provides a wind turbine that converts wind energy into power with a controllable pitch angle of the blades, an induction machine driven by this power, and an induction machine that acts as a generator to rotate the wind turbine. A generator output proportional to the cube of the number can be obtained, and
The ratio of generation voltage/operating frequency remains constant from the rotation speed at which power generation starts to the rotation speed at which the rated output is generated, and the sliding frequency of the induction motor is adjusted so that the generator voltage remains constant at the rotation speed at which the rated output is generated or higher. The pitch angle of the blades is constant in the operating range from the start of the wind turbine to the rated rotation speed, and the wind turbine rotation speed is within the set rotation speed range in the operating range above the rated rotation speed. This is a wind power generation device in which the pitch angle of the blades is controlled.

With this configuration, variable speed control operation is performed at the number of rotations (rotational speed) of the wind turbine that corresponds to the wind speed, absorbing torque fluctuations due to changes in wind conditions as inertia, and rotating the wind turbine according to the output characteristics of the wind turbine. The output power is controlled in proportion to the cube of the number, and for the reasons described below, operation control can be performed at a constant circumferential speed ratio, and the maximum effective number of energy can be 1.

The reason why it is possible to control the circumferential speed ratio at a constant level and effectively acquire energy by controlling the rotation speed fj in accordance with the wind speed will be explained below.

The basic characteristics of the output from a propeller-type wind turbine are as follows: % ρ: air density, ■: wind speed, Cp: power coefficient, R: propeller radius, ω: angular velocity power coefficient Cp=2P/ρπR2V3...(2) Circumferential speed ratio TSR=ωR/v・(3) Here, in order to obtain the maximum efficiency as a wind turbine, it is sufficient to perform control to always maintain the maximum value of the power coefficient Cp, which makes it possible to obtain the maximum effective energy. Become.

As shown in Fig. 2, the power coefficient Cp characteristic of the wind turbine has its maximum point depending on the pitch angle β of the wind turbine blades,
Moreover, it is a function of the circumferential speed ratio TSR.

Therefore, when the pitch angle β of the wind turbine blades is set to a certain value, the circumferential speed ratio TSR at which the power coefficient cp becomes maximum is determined.

However, as can be seen from the above equation (3), the circumferential speed ratio TSR is
Since it is determined by the angular speed ω and the wind speed ■, if the circumferential speed ratio TSR is to be kept constant, if the wind speed V changes, the rotational speed must also change.

Therefore, if the pitch angle β of the wind turbine blades is fixed to maximize energy acquisition in accordance with the wind conditions, it is sufficient to perform rotational speed control in accordance with the wind speed, that is, constant circumferential speed ratio control.

Now, assuming that the circumferential speed ratio TSR at which the power coefficient Cp is maximum is Ω, the output P of the wind turbine is expressed as a function of the rotation speed N as follows.

Ω-ωR/v...(4) ■=ωR/Ω...(4゛) ω-2πN/60...(5) However, N: III car rotational speed pH1) (5), (4 '
) Formula v=R/Ω・πN/30...(6)(1),
From formula (6), P=y2P7CR2Cp max (R
πN/30Ω)3=1.8x10-3ρR5Cpmax
(1/Ω3)N3...(7) From equation (7), it can be seen that the output P of the wind turbine is proportional to the cube of the rotation speed N, and constant circumferential speed ratio control can be performed using the rotation speed N as information. It turns out to be a good thing.

Figure 3 shows the characteristics of these wind turbines with respect to power coefficient Cp, output P, and rotational speed N under torque. In the figure, the horizontal axis shows the rotation speed N, and the vertical axis shows the characteristic curves of the power coefficient Cp (solid line), output P (ttJ line), and torque T (dotted chain line) at each wind speed ■1 to ■7. , line P indicates the rated load. As can be seen from the figure, the output P shows the maximum value at the rotation speed N where the maximum value (Cpmax) of the power coefficient Cp is obtained at each wind speed 1 to v7, and therefore,
By maintaining CplaX, the output P has the characteristics of the curve (A), and the torque T at that time has the characteristics of the curve (B). In other words, by keeping the power coefficient Cp at its maximum value,
The level of the output P is uniquely determined by the rotation speed N of the wind turbine. Therefore, if the power-to-power converter is controlled so that a predetermined output P determined according to the rotational speed N is generated, energy can be obtained effectively.

In Fig. 3, N is the cut-in rotation speed corresponding to the cut-in wind speed (■o) at which power generation starts, and NVL is the rated rotation speed corresponding to the rated wind speed V [at which the rated output of the wind turbine is generated. be.

(Example) FIG. 1 shows an example of the configuration of the apparatus of the present invention. In the same figure, 1
It is a propeller-type rotor with a mechanical pitch control part for the blade pitch angle, and a loaf power is generated.
3 is a power converter, and this converter 3 has an excitation function to make the induction machine 2 driven by the power of the windmill 1 function as an induction generator, and a rotation speed detection function. It has a control function that generates power proportional to the cube of the rotation speed of the wind turbine detected by the wind turbine 4, and the ratio of power generation voltage/operating frequency from the rotation speed at the start of power generation to the rotation speed at which the rated output is generated. is constant, and the function is to control the slip frequency of the induction machine so that the generator voltage is constant above the rotation speed that generates the rated output. In this configuration example, the converter 3 also has the function of converting the generated AC power into DC power, and the output end of the converter 3 is equipped with a battery 5 that stores the generated energy, and a battery 5 that stores the generated energy. The stored electrical energy is shared with grid 6 1!1
1 and sends it to the system 6.

Next, a control chart of the above-mentioned wind power generation device will be explained with reference to FIG. In the figure, the horizontal axis shows the wind speed ■, the vertical axis shows the output P and the rotation speed N, and Vs is the moment when the wind turbine starts rotating.
Fill wind speed, ■o is cut-in wind speed at which power generation starts,
■LG is the rated wind speed at which the rated output of the wind turbine can be obtained, ■co
is the cut-out wind speed at which wind turbine operation is stopped and the energy of the feathering wind is released, Pl- is the rated output as a wind power generator, NVC is the cut-in rotation speed, NvL is the rated rotation speed, and the operation up to this rotation speed is In the range, the pitch angle of the blade is kept constant, and in the operating range of the rotation speed from this point onwards, the pitch angle of the blade is controlled so that the wind turbine rotation speed falls within a predetermined rotation speed range. NN is the no-load set rotation speed of the wind turbine, the upper 10% of NN is the control rotation speed range that is controlled from 1 to roll by pitch control, the curve PR is the loss power, and the period between VS and vo is the mechanical loss of the generator and the gear transmission loss (2
(squared curve), ■ o time 4, one member of the generator is excited, and v
Between NVL is excitation loss and total mechanical loss, and between VL and VCO is generator excitation loss and mechanical loss (almost constant).

The operating conditions in FIG. 4 are as follows.

■Standby: When the wind speed is between O and ■5, no power is generated and the converter 3 does not operate.

■Start-up: J speed ■ Between 5 and Vc, wind energy can be used as energy to rotate the windmill.

■Cut-in: The wind power generator becomes ready to start generating electricity, and the induction machine 2 is excited.

(2) Zero-load control region: In the darkness of the wind speed V-VL, the maximum output control explained in FIG. 3 is performed. In other words, the generated power is controlled so that the rotational speed matches each wind speed situation. As a result, the output P exhibits an output characteristic proportional to the cube of the wind speed (number of rotations), and maximum output control is performed at each number of rotations.

The rotation speed N rises from Vs and rises while being balanced with the moment of inertia of the wind turbine, and after VC it is operated in proportion to the wind speed. Note that the process in which the rotational speed increases and the process in which the rotational speed decreases as the wind becomes weaker exhibit hysteresis characteristics as shown by the arrows.

■Negative fixed region: During the wind speed V 1 "" V co, the output P is held constant, the input wind energy is released by the mechanical pitch control l-roll, and the rotation speed N is
N is controlled within a range of 10%.

■Standby: Wind speed■. . In the above wind conditions, the wind energy exceeds the capacity of the equipment, so a mechanical governor is used to feather the wind turbine to release the energy and maintain the wind turbine in a safe state.

Next, regarding the excitation and control of the induction machine 2 by the converter 3 in FIG. 1 described above, that is, the operation of the induction generator, the fifth
This will be explained with figures. Figure 5 shows the characteristics of an induction machine, with the motor region being positive and the power generation region being negative, the horizontal axis showing the excitation frequency, and each solid curve representing the output characteristics at each excitation frequency.
Each dashed line curve represents torque characteristics. The operating range a as a generator is the cut-in rotation speed of the wind turbine from N to NN.
C + ΔN, and in order to use a 3φ (phase) 4P (pole) induction machine, determine the speed increase ratio of the speed increaser so that the rated rotation speed NvL of the wind turbine becomes the electrical frequency of the induction machine 601-1 z. Zuru.

To control the induction machine, as shown in Fig. 5, an operation is performed with the input voltage V/station wave f = constant for the induction machine from the cut-in rotation speed Nvc to the rated rotation speed Nv1-. ,
At the rated rotation speed "vl-" or higher, operation is performed with the input voltage V = constant.In other words, from the cut-in rotation speed N to the rated rotation speed "vL", the load control range where C output control is performed in accordance with the input is already in place. , the output and torque are controlled to increase as the rotation speed increases as shown in songs F11 (C) and (D), and the wind turbine pitch control control range 1111 NN±ΔN is controlled from the rated rotation viNVL.
The problem is in the fixed load range C where constant output control is performed, the output is constant as shown by curve (c), and the torque is controlled in inverse proportion to the rotational speed as shown by curve (d).

For such control, the frequency on the induction machine (generator) side, which corresponds to the rotation speed of the wind turbine, must be the synchronous frequency rIl (t error is zero).
[Slip frequency control] such that the output and torque characteristics as shown in Figure 5 are added, and the frequency becomes the sum of the slip frequency (the more negative the slip, the greater the output)
All you have to do is

FIG. 6 shows an example of a specific configuration for executing the above control.

In the same figure, 30 is a converter as the main body structure of the converter 3 (FIG. 1), and 31 is a converter that detects the rotation speed of the wind turbine by the rotation speed detector 4 based on a predetermined relationship between the rotation speed and power (for example, rotation speed). 32 is the rotation speed-power conversion circuit which converts the output signal PREF into the output signal PREF using the cube of the number
Comparison means for comparing the output P of the power conversion circuit 31 and the converter 30; 33 is a compensation circuit to which the output of the comparison means 32 is inputted to match the characteristics of the system; 34 is a compensation circuit for receiving the output of the rotation speed detection "a4; F that performs frequency-voltage conversion
/V converter, 35 is the above-mentioned compensation circuit 33 and F/V converter 3
Comparison means for comparing the output of No. 4 with the output of No. 4, 36 is the comparison means 3
This is a command circuit that generates an excitation frequency command signal based on the output of the converter 5, and these constitute the control section of the converter 3.

As described above, since the output of the wind turbine that takes the power coefficient Cp max point is determined based on the rotation speed of the wind turbine, the rotation speed of the wind turbine is converted into the output signal PREF by the rotation speed-power conversion circuit 31, and this output By comparing the signal P with the output P from the converter 30 and the rotation speed of the wind turbine through the compensation circuit 33, that is, the output of the F/V converter 34, the excitation frequency command circuit 36 In other words, the excitation frequency command circuit 36 controls the generator voltage (excitation voltage)/operating frequency = constant until the rated rotation as described above, and maintains the rated rotation. In the above range, the generator voltage (excitation voltage) is controlled to be constant, thereby preventing magnetic saturation of the induction machine 2 and maintaining good output characteristics.

In this way, the converter 30 performs slip frequency control 211 on the induction Ia2 using an output signal proportional to the cube of the rotation speed N of the wind turbine, and by controlling its output power, control is achieved that matches the output characteristics of the wind turbine. The wind turbine has variable speed and constant circumferential speed ratio control, making it possible to obtain maximum effective energy.

In addition, by controlling the wind turbine at variable speed and the blade pitch angle of the wind turbine to a predetermined state according to the wind speed, even in wind conditions with low average wind speed, power can be effectively generated and energy can be regenerated. In particular, it is possible to improve the versatility as a small power generation device using an induction machine.

(Effects of the Invention) As described above, according to the present invention, the induction motor acts as a generator, and the converter adjusts the slip frequency so that an output of ff1lfi proportional to the cube of the number of rotations of the wind turbine is obtained. By controlling the wind turbines, the wind turbines are operated with variable speed control that operates at a rotation speed according to the input, and are also operated with constant circumferential speed ratio control, making it possible to efficiently regenerate a large amount of energy and at the same time To absorb torque fluctuations caused by sudden changes in conditions, to prevent cost increases in terms of structural materials, to improve reliability, and to have a configuration that can effectively generate power in low wind speed ranges. is easy, and the versatility of a power generation device using an induction machine can be improved.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing an example of the wind power generation device of the present invention, Fig. 2 is a characteristic diagram of the power coefficient with respect to the circumferential speed ratio of the wind turbine to explain the present invention, and Fig. 3 is a diagram showing the power coefficient of the wind turbine as well. Power coefficient and output relative to rotational speed. Fig. 4 is a control diagram to explain the control of the device, and Fig. 5 is a characteristic diagram of generator output and torque with respect to excitation frequency to explain the action of the device. FIG. 6 is a configuration diagram showing a specific example of the device. 1...Windmill, 2...Induction machine, 3...Converter, 30
Converter, 31 Rotation speed-power conversion circuit, 36 Excitation frequency command circuit. Patent Applicant: To7 Maha Motion Co., Ltd. fi
2 Figure-side 'L9 T5 shaku

Claims (1)

[Claims] 1. A windmill that converts wind energy into power with a controllable pitch angle of the blades, an induction machine driven by this power, and an induction machine that acts as a generator and is proportional to the cube of the rotation speed of the windmill. When generator output is obtained, the ratio of generator voltage/operating frequency is constant from the rotation speed at which power generation starts to the rotation speed at which rated output is generated, and the generator voltage remains constant at or above the rotation speed at which rated output is generated. It consists of a converter that controls the slip frequency of the induction machine so that the pitch angle of the blades is constant in the operation range from the start of the wind turbine to the rated rotation speed, and the wind turbine rotation speed is kept constant in the operation range above the rated rotation speed. A wind power generation device characterized in that the pitch angle of the blades is controlled so as to fall within a set rotation speed range.