JPH0127269B2 - - Google Patents

Description

[Detailed Description of the Invention] (A) Industrial Application Field This invention relates to improvement of a power generation device that utilizes wind power.

(B) Conventional technology Wind power generation involves incorporating wind energy into a power generation system. To do this efficiently, it is first necessary to operate the wind turbine at an angular speed proportional to the wind speed. In this case, the output torque is proportional to the wind speed. Proportional to the product of the square and the air density. Since this output is expressed as the product of angular velocity and torque, the wind turbine output is ultimately proportional to the product of the cube of the wind speed and the air density. On the other hand, wind is a living thing, and it is normal for it to be accompanied by temporal fluctuations, and it also changes greatly depending on the season. Therefore, the wind turbine output, that is, the usable wind energy, fluctuates greatly, making large-scale use difficult and forcing us to adopt a decentralized form of use in the short to medium term.

(C) Problems to be solved by the invention In conventional battery-type small and medium-sized wind power generators, optimal control of the wind turbine load with respect to wind speed is not performed, or in other words, the matching between the wind turbine and the generator is poor. Energy capture efficiency is low, specifically around 10% of wind energy.

For this reason, a technology has been proposed in which wind energy is applied to hydraulic technology to rotationally drive a generator instead of a battery-type wind power generator. For example, Kaihatsu No. 51-85059 ``Wind power generation method''
An example is No. 51-121120 "Wind power generator". In these examples, a method is adopted in which the converted hydraulic pressure is stored in consideration of the above-mentioned characteristics of wind energy, that is, the fact that it is accompanied by temporal fluctuations.
However, these proposed power generation systems do not take any measures to extract hydraulic energy proportional to wind speed, and the efficiency of capturing wind energy is still not sufficient.

The present invention aims to provide a wind power generation device that solves these conventional problems.

(D) Means for Solving the Problems The wind power generation device according to the present invention includes: a variable displacement hydraulic pump driven by a wind turbine; a hydraulic accumulator that stores hydraulic pressure from the hydraulic pump;
A hydraulic motor driven by pressure oil accumulated in the hydraulic accumulator, an alternator driven by the hydraulic motor to generate electricity, and a signal output mechanism that outputs a signal proportional to the square of the wind speed acting on the wind turbine. , a hydraulic pump control mechanism that controls the discharge amount per rotation of the variable displacement hydraulic pump based on the output signal of the signal output mechanism.

(E) Function In the hydraulic circuit according to the present invention, the pressure oil supplied to the fixed displacement hydraulic motor that rotationally drives the induction generator is directly supplied from the variable displacement hydraulic pump that is rotationally driven by the windmill. Instead, it is stored in a single hydraulic accumulator.

On the other hand, a variable displacement hydraulic pump, which is rotationally driven by a windmill which is rotated at an angular velocity proportional to the wind speed and is operated efficiently, constantly replenishes the hydraulic accumulator with pressure oil.

(F) Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic explanatory diagram of an embodiment, particularly an embodiment device when incorporated into an existing power grid. 1 in the diagram
2 is a propeller-type windmill, and 2 is a variable displacement hydraulic pump rotationally driven by the windmill, and the discharge amount can be changed as described later. 3 is a plurality of hydraulic accumulators connected to the discharge side of the hydraulic pump 2, that is, the high pressure side hydraulic circuit 2', and 4 is a fixed displacement hydraulic motor. Reference numeral 5 denotes a three-phase alternating current alternating current generator, such as a synchronous generator or an induction generator, which is rotationally driven by the three-phase alternating current alternating current generator, and is connected to a three-phase alternating current power grid 6 via a switch 7. 8 is a check valve, 9 is an electromagnetic on-off valve,
When the switch 7 is OFF, it is closed, and when it is ON, it is open. 10 is an oil tank, and 11 is an electric motor and other loads.

The variable displacement hydraulic pump 2 is capable of continuously increasing the discharge amount per revolution by varying the eccentricity from 0.

Next, the operation of this device will be explained.

The propeller-type windmill 1 is always facing the headwind and is rotated, for example, in a counterclockwise direction as shown by an arrow, thereby rotationally driving a variable displacement hydraulic pump 2. Then, the hydraulic pump 2 sucks hydraulic oil from the oil tank 10,
It is pressurized and discharged into the discharge side oil passage 2'.

By the way, in order to operate the wind turbine 1 efficiently, it must be rotated at an angular velocity proportional to the wind speed. Therefore, if the required input shaft torque of the hydraulic pump is always matched to the output torque of the rotating shaft, which is proportional to the square of the wind speed obtained in that case, and the output/load matching control is performed, the operation of the wind turbine can be improved. The optimal condition is satisfied for . This invention takes this point into consideration and employs the special configuration described below. By the way, in general, the input shaft torque T of a hydraulic pump is expressed as: T = △p・If the pump pressure (outlet pressure - inlet pressure) is △p, and the displacement volume per rotation of the pump (discharge amount per rotation) is D, then T = △p・It is expressed as D/2π, and if the wind speed is v and the output shaft torque of wind turbine 1 is Tw, when operating under the above conditions, Tw = Kv ² (K is a proportionality constant), so T = Tw i.e. △p・
It is sufficient to control the operation of the hydraulic pump 2 so that D=2πKv ² .

Specifically, a bladder-shaped hydraulic accumulator 3, for example, is used, and a relief valve (not shown) is connected to the discharge side oil passage 2'.
This relief pressure is set to the maximum allowable pressure of the accumulator. Therefore, when pressure oil is delivered from the hydraulic pump 2 to the discharge side oil passage 2', the gas pressure sealed in the gas chamber of the accumulator 3 (initial pressure of the accumulator) acts, but in addition, the pressure from the hydraulic pump 2 is applied. The gas chamber is compressed by the inflow of pressure oil, and wind energy can be stored until the pressure reaches the maximum allowable pressure (relief pressure) of the accumulator.

That is, the input pressure of the pump described above is constant at atmospheric pressure, and the outlet pressure approaches a constant value limited by the relief pressure as described above. Further, the circuit 2'
A pressure switch is attached to the pressure switch, and the pressure switch is configured to operate when the pressure in the circuit 2' reaches an appropriate predetermined pressure between the set pressure of the relief valve and the initial gas pressure of the bladder type accumulator 3. . Therefore, due to this operation, the electromagnetic on-off valve 9 is opened, and the fluctuation amplitude of Δp becomes even narrower. Then, the Δp is treated as approximately constant, and the hydraulic pump 2 is controlled so that the discharge amount D per revolution is proportional to the square of the wind speed v during operation of the hydraulic pump 2. Generally speaking, if you let a wind turbine rotate without load at a certain wind speed and gradually increase the load (brake torque), then if you gradually strengthen the brakes from no-load operation, the torque will increase. The speed decreases almost in proportion to, and the two are inversely proportional to each other. In this case, since the wind turbine output is the product of torque and speed, the product is at its maximum when both values are approximately in the middle. This means that the maximum power can be extracted from the wind turbine when a load torque is applied that reduces the speed to approximately 1/2 of the no-load speed.
If the load is too high or too low, the wind turbine's output will decrease and efficiency will decrease. Said pump pressure△
p corresponds to exactly this load, so this △
It is important to keep the p value constant, and for this purpose the discharge amount D of the hydraulic pump is controlled. This allows the wind turbine 1 to be operated efficiently.

As this control method, as shown in the figure, an anemometer 12 is provided near the wind turbine 1.
The anemometer 12 has a built-in signal output mechanism configured to output a signal corresponding to the square of the wind speed V measured by 2. A hydraulic pump control mechanism 13 consisting of a pulse motor or the like is actuated by a signal from this signal output mechanism. The eccentricity of the hydraulic pump 2 is changed by the operation of the hydraulic pump control mechanism 13, and the discharge amount D per revolution is controlled in proportion to the square of the changing wind speed v.

Now, when the pressure oil from the hydraulic pump 2 whose discharge amount is controlled in this way is accumulated in the hydraulic accumulator 3, and the circuit pressure of the high pressure side hydraulic circuit 2' reaches the predetermined pressure, the pressure switch is activated. However, at the same time as the switch 7 is closed, the solenoid valve 9 is opened. and fixed displacement hydraulic motor 4
The three-phase induction generator 5 is driven to rotate by high-pressure oil supplied from the high-pressure side hydraulic circuit 2' via the on-off valve 9, and electric power is sent to the three-phase power grid.

Next, a case where the AC generator is an induction generator will be explained.

Figure 3 shows the motor torque and regenerative braking torque of a three-phase induction motor as percentages of the rated torque in the normal operating range N and the regenerative control range R, and the dotted curve shows the percentage of the rated torque. The figure shows changes in current corresponding to motor torque and regeneration control torque. The vertical axis in the center of the figure shows the synchronous rotation speed range. From this figure, in the induction motor, the regenerative control torque is the rated torque (torque ratio 100%)
It can be seen that if the rotational speed is approximately twice that of the rotational speed or less, constant speed operation is maintained very close to the synchronous rotational speed, the motor operates as a generator during that time, and the generated current is sent to the power main line.

If the motor pressure (inlet pressure - outlet pressure) of the hydraulic motor 4 is △p', and the displacement volume per motor rotation is D', then the output shaft torque T' = △p'・D'/2
Since it is a fixed capacity type, D' is constant, so the output shaft torque T' is proportional to the motor pressure (Δp'), that is, the circuit pressure of the high pressure side hydraulic circuit 2'.

The pressure of this high-pressure side hydraulic circuit 2' is automatically determined based on the pressure accumulation state of the hydraulic accumulator 3, but its fluctuation range is small as described above.

Even if the output shaft torque T' of the hydraulic motor 4 varies slightly in proportion to this circuit pressure, the hydraulic motor 4 continues to operate at a substantially constant speed, which is slightly faster than the synchronous rotational speed, and is connected to the power grid 6. Power will be transmitted.

In the hydraulic circuit according to the present invention, the pressure oil supplied to the fixed capacity hydraulic motor 4 that rotationally drives the induction generator 5 is directly supplied from the variable capacity hydraulic pump 2 that is rotationally driven by the wind turbine 1. Rather, it is temporarily stored in the hydraulic accumulator 3 and then supplied via the hydraulic circuit 2' shown by the thick solid line. On the other hand, a variable displacement hydraulic pump 2, which is rotatably driven by a wind turbine 1 which is rotated at an angular velocity proportional to the wind speed and operated efficiently, constantly replenishes the hydraulic accumulator 3 with pressure oil. There are certain characteristics.

The following energy conversion process exists in this wind power generation device constituting the system of the present invention for converting wind energy into electric energy.

(A) Wind energy → Rotating mechanical energy (B) Rotating mechanical energy → Hydraulic energy (C) Hydraulic energy → Pressure energy (D) Pressure energy → Hydraulic energy (E) Hydraulic energy → Rotating mechanical energy (F) Rotating mechanical energy → In the six stages of electrical energy, the exchange efficiency in the exchange process (B) is 90-50%, and in the exchange process (C) and (D), it is both 90%, and the conversion process
In (E) and (F), it seems to be about 90% and 85%, respectively, and since about 55 to 30% of the rotating mechanical energy taken in by the wind turbine is converted into electrical energy, this device is different from the conventional one. It has a conversion efficiency that is at least three times higher than that of a battery-type wind power generator.

However, this is assuming that the wind energy received by the wind turbine, that is, the conversion efficiency in (A) above, is the same, and this device uses a control method to operate the wind turbine efficiently as described above. Therefore, it is clear that the difference in overall efficiency between the two becomes even larger.

Next, another embodiment of the apparatus operated as an independent power generation plant according to the present invention will be explained based on the schematic explanatory diagram of FIG. 2. The difference between this other embodiment device and the previously described embodiment device is that the number of hydraulic accumulators 3 is increased, and a variable displacement hydraulic motor 14 is used instead of a fixed displacement type hydraulic motor. The generator rotated thereby is an alternating current generator (the one shown is a three-phase generator, but a single-phase generator may also be used). The other constituent parts are the same as those in the previous embodiment, and the same numbers are given to them, and the explanation thereof will be omitted.

In this other embodiment, an independent hydraulic accumulator type wind power generation system is configured to transmit power as an independent power generation plant separate from the existing power line, and an increase in load 11 can be handled within this system. Therefore, the number of hydraulic accumulators 3 is increased to increase the amount of stored energy, and the hydraulic motor that drives the alternator 15 is equipped with a variable capacity so that it can immediately respond to fluctuations in the electric power load 11. A type hydraulic motor 14 is used. The hydraulic motor 14 is configured such that the displacement volume per revolution can be continuously increased by, for example, varying the amount of eccentricity from 0.

The circuit pressure of the high-pressure side hydraulic circuit 2' is automatically determined based on the pressure accumulation state of the hydraulic accumulator 3 as described above, but since the fluctuation range is not so large, the output torque of the hydraulic motor 14 is approximately It is proportional to the displacement volume. Therefore, when the power load 11 increases and the load on the alternator 15 increases, and it is necessary to increase the input torque thereto, the eccentricity of the hydraulic motor 14 is increased. The displacement volume may be increased to increase the output torque, and conversely, when the power load 11 is reduced, the displacement volume may be decreased and the output torque may be decreased. In this method, the amount of eccentricity of the hydraulic motor 14 is changed by the output signal from the tachometer so that the alternator 15 operates at a substantially constant speed corresponding to a certain frequency.

Next, in the embodiment shown in Fig. 1, during daily operation, wind energy is converted into pressure energy and stored in the hydraulic accumulator 3 for 16 hours including the middle and night hours of the day, and surplus is generated for 8 hours during the day. An example of a trial calculation of the capacity of the hydraulic accumulator 3 when the induction generator 5 is driven by the fixed capacity hydraulic motor 4 while also accumulating, and the mode is used to supply 5KW flat power to the power main line 6. is shown below.

5KW×10 ³ NmS ^-1 ×m ² /0.85* ¹ ×0.90* ² ×17.5* ³ ×10
⁶ N = 3, 74×10 ^-4 m ³ /S ... (a) (3, 74 x 10 ^-4 m ³ /S x 8hr x 3600S) x 2/3 = 7, 17m ³ ... (b) 7, 17m ³ × 4 = 28, 7m ³ <4m × 4m × 2m
...(C) Equation (B) is a calculation of the required amount of pressure oil per second flowing from the hydraulic accumulator 3 to the fixed capacity hydraulic motor 4 shown in Fig. The energy conversion efficiency *2 is the same efficiency as that of the fixed displacement hydraulic motor 4, *3 is the average value assuming that the hydraulic accumulator 3 is used at a pressure between 20 MPa and 15 MPa. (B)
The formula calculates 2/3 of the required oil amount for 8 hours of daytime operation from the required amount of pressure oil per second determined by equation (a), and stores it in the hydraulic accumulator 3 for 16 hours including nighttime. This is the amount of pressure oil that should be kept.

In a hydraulic accumulator, the net accumulated pressure oil amount is generally about 1/4 of its nominal capacity, so the required nominal capacity of the hydraulic accumulator 3 is 28.7 m ³ as shown in equation (c). For example, if this is buried underground, 4m x 4m x 2
A space of about m is sufficient.

By burying the hydraulic accumulator in an underground trench or the like, it is insulated from changes in the temperature of the outside air, and stable pressure accumulation can be achieved.

(G) Effect of the Invention As is clear from the above explanation, in the wind power generator according to the present invention, control with good response to wind speed fluctuations is performed in the first conversion process of wind energy. Since a variable displacement hydraulic pump is used, wind energy capture efficiency is good over a wide range of wind speeds.

In the embodiments described above, a horizontal shaft type propeller type wind turbine is used, but it is of course possible to use a vertical shaft type, for example, a Darius type wind turbine.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of an embodiment of the present invention, particularly an embodiment device when incorporated into an existing power grid, and Fig. 2 is a schematic explanatory diagram of another embodiment device operated as an independent power generation plant. , FIG. 3 is a torque characteristic diagram of a three-phase induction motor. 1...Windmill (propeller type windmill), 2...Variable displacement hydraulic pump, 3...Hydraulic accumulator, 4
...Hydraulic motor (fixed capacity hydraulic motor), 5...
... Generator (induction generator or synchronous generator), 6...
... Power grid, 11 ... Power load, 12 ... Anemometer (signal output mechanism), 13 ... Hydraulic pump control mechanism,
14...Hydraulic motor (variable displacement hydraulic motor),
15... Generator (AC generator), 16... Independent power line.

Claims (1)

[Claims] 1. A variable displacement hydraulic pump driven by a windmill, a hydraulic accumulator that accumulates hydraulic pressure from this hydraulic pump, and a hydraulic motor that is driven by the pressure oil accumulated in this hydraulic accumulator. , an alternator driven by the hydraulic motor to generate electricity; a signal output mechanism that outputs a signal proportional to the square of the wind speed acting on the wind turbine; A wind power generator comprising: a hydraulic pump control mechanism that controls the discharge amount per revolution of the pump. 2. A patent claim characterized in that the hydraulic motor is a fixed capacity hydraulic motor, the alternating current generator is an induction generator or a synchronous generator, and the output side of the induction generator or synchronous generator is connected to a power grid. The wind power generation device according to scope 1.