JP2019191679A - Power generating set - Google Patents

Abstract

To provide a power generating set applicable even for tidal power generation equipped with a turbine and a generator subject to unavoidable steep fluctuation in flow velocity and the like, capable of following the steep fluctuation in the flow velocity and the like so as to reach the maximum power point using hill-climbing control.SOLUTION: A power generating set 1 includes: a turbine 2 that generates rotational torque in response to external force from fluid; a generator 3 that generates power using the torque of the turbine 2; a turbine torque detector 21 for detecting the torque of the turbine 2; and a control unit 4 that performs a maximum power point tracking control using a hill-climbing method that determines an operation amount of next output torque of the generator 3 by changing the operation amount of output torque of the generator 3 and based on comparison results of power values of before and after the changes. The control unit 4 includes a torque addition controller 42 that can add torque including a difference between a torque detected when torque detection processing is executed by the turbine torque detector 21 and a torque output from the generator 3 to the operation amount of output torque of the generator 3 determined by hill-climbing method.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control technique for a power generation device that uses a fluid among renewable energies, and particularly relates to a technique that is effective for controlling a generator to operate near a maximum power point.

  Conventionally, in order to prevent global warming and save energy, various power generators using renewable energy such as solar, wind, hydropower, geothermal, and biomass that can be used permanently have been developed. Efforts toward practical application are being actively carried out.

  The most widespread use of renewable energy is photovoltaic power generation that is installed using farmland inappropriate land, farmland abandoned land, flat land such as vacant land, and roofs of various buildings. As a technique for obtaining highly efficient power in a solar power generation system, a maximum power point tracking (MPPT) control technique called a hill-climbing method is generally known (see Patent Document 1).

  The control technique in the hill-climbing method described in Patent Document 1 is that a solar cell is operated at two different operating points and the output power is compared while the operating point of the solar cell is the maximum power output point (hereinafter referred to as “maximum power point”). ) And is controlled so as to climb toward the top of the graph showing the voltage-power characteristics. Note that the output power of the solar cell can be calculated by multiplying the output voltage and the output current.

  For example, when the solar cell has a voltage-power characteristic (power curve) as shown in FIG. 8 under a certain amount of solar radiation, the output voltage of the solar cell is first changed from the open voltage, When the power exceeds the maximum power point, the output power decreases in the A direction from the top of the graph showing the voltage-power characteristics. In hill-climbing control, this decrease in output power is detected and the output voltage is reduced. By doing so, the output power increases in the direction toward the top of the graph showing the voltage-power characteristics. When the maximum power point is exceeded again, the output power decreases from the apex of the graph showing the voltage-power characteristics in the B direction (the reverse direction of the A direction). By detecting the decrease in the direction and increasing the output voltage, the output power increases in the direction toward the top of the graph showing the voltage-power characteristics.

  In hill-climbing control, it is possible to reciprocate the output voltage in the vicinity of the maximum power point and follow the maximum power point of the solar cell by repeating the above operation. Although hill climbing control is a relatively simple and easy-to-handle algorithm, it repeatedly follows the condition judgment so that it always becomes the maximum power point, and even if the power curve changes due to secular change, etc., it can follow the maximum power point. Widely used in solar power generation and wind power generation.

  As power generation equipment that uses renewable energy such as solar and wind power is spreading, development of power generation technology that uses enormous marine energy resources (ocean current, tidal current, wave power, ocean temperature difference) around Japan In recent years, technological development for practical use has been promoted. In particular, tidal current power generation using a horizontal flow caused by tide fullness is not a constant flow velocity, but since the change is periodic, the power generation output can be predicted in advance. In addition, tidal current power generation can be installed at a location relatively close to the land, and installation costs and power generation costs can be reduced by using bridge piers and harbor structures. Tidal power generation uses the power of the ocean current itself, and is different from tidal power generation that generates power by creating a weir in the estuary and creating a drop due to tidal flow.

  The tide continues to flow at an almost constant speed, changing direction every 6 hours due to the tide. Tidal power generation uses this tidal power to generate electricity, so it can supply more stable power than solar power and wind power, which are affected by the weather, and is attracting attention as a reliable energy source. Yes. In tidal current power generation, the facility utilization rate, which is the actual power generation capacity with respect to the power generation capacity, can be expected to be around 40%, and the power generation efficiency is nearer than that of land wind and offshore wind power, where the facility utilization rate is 20% or 30%. It has been understood by research of time.

JP 2012-028435 A

  By the way, as shown in FIG. 9, the change of the tidal current flow velocity is a gradual change in a sinusoidal shape (not a clean sine wave but a sine wave shape in shape) of 12 hours in one cycle. In addition, although the barnacles and the like adhere to the turbine, the output torque of the turbine decreases. Even if the power curve changes due to such aging, the maximum power point tracking control by the above-mentioned hill-climbing method has a maximum. Since it can be expected that the power point can be followed, such control is considered to be an effective control method.

  However, as shown in FIG. 10 and FIG. 11, the actual tidal flow velocity has many large fluctuations (turbulence) in a short time. As a result of the verification by the present inventor, it has been found that there is a risk that control failure may occur due to loss of the optimal point. In particular, assuming a configuration in which a turbine is arranged in the vicinity of a structure such as a bridge pier from the viewpoint of convenience of installation, etc., an increase in the flow velocity can be expected, but the fluctuation in the flow velocity in a rapid cycle also increases, and the maximum power point can be tracked. It seems that there will be a problem that it cannot be done.

  Here, in the maximum power point tracking control in the photovoltaic power generation system, when there is a steep fluctuation (when it deviates to the extent that the maximum power point tracking control is not possible), the current is changed and reset (scanned) once again. By performing the maximum power point tracking control, the maximum power point can be tracked. In other words, in the case of photovoltaic power generation, when the maximum power point tracking control cannot be performed, the maximum power point can be quickly found and tracked by sweeping (changing) the voltage once the voltage is released and then scanning. it can.

  However, since the tidal current power generation device is a power generation device including a turbine and a power generator, in order to scan the maximum power point, it is necessary to sweep the number of revolutions of the power generator. Is significantly worse.

  It has been found by the present inventors that such a problem is not limited to a tidal current power generation device, but is the same in a rotating power generation device including a turbine and a generator. Examples of the rotating power generation device using a fluid include a tidal current power generation device, an ocean current power generation device, a wave power generation device, an ocean temperature difference power generation device, a tidal power generation device, and a wind power generation device.

  The present invention has been made paying attention to such points, and the main object of the present invention is a power generator (rotating system) including a turbine and a generator such as tidal current power generation in which a steep fluctuation such as a flow velocity cannot be avoided. Provides a power generator capable of controlling the generator to operate near the maximum power point using hill-climbing control so that the maximum power point is reached in response to steep fluctuations in the flow velocity, etc. There is to do.

  Here, the energy obtained from the turbine, that is, the turbine torque, is determined by the flow velocity and the rotational speed of the turbine. Therefore, when the flow velocity fluctuates, the rotational speed of the turbine does not change suddenly, so that the turbine torque fluctuates. In response to such fluctuations in turbine torque, the output torque of the generator by hill-climbing control changes only slowly because of low response. As a result, the rotation speeds of the turbine and the generator change with a delay from the flow velocity fluctuation.

  The present inventor considers the problem that the rotational speed of the turbine and the generator changes with a delay from the flow velocity fluctuation, and as a result of intensive investigation, as a result of the fluctuation of the turbine and the generator, the fluctuation of the rotational speed of the turbine and the generator is delayed. It has been found that the phenomenon that the turbine torque fluctuates and the maximum power point is lost is generated.

  Therefore, in order to prevent the situation where the maximum power point is lost due to such circumstances, the power generation apparatus according to the present invention prevents the turbine and generator rotation speeds from being delayed and fluctuated due to flow speed fluctuations. This is based on the technical idea of canceling torque fluctuations.

  That is, a power generation apparatus according to the present invention includes a turbine that generates rotational torque by receiving external force from a fluid, a generator that generates power using the torque of the turbine, a turbine torque detection unit that detects actual torque or estimated torque of the turbine, A control unit that performs maximum power point tracking control using a hill-climbing method that changes the operation amount of the output torque of the machine and determines the operation amount of the output torque of the next generator based on the comparison result of the power value before and after the change As a control unit, the torque of the generator determined by the hill-climbing method is determined including the difference between the detected torque and the output torque of the generator at the time when the torque detection process is executed by the turbine torque detection unit. A torque addition control unit that can be added to the operation amount of the output torque is provided.

  In the present invention, “the detected torque when the torque detection process is executed by the turbine torque detection unit” is either “the actual torque of the turbine obtained by measurement” or “the estimated torque of the turbine obtained by calculation”. If it is. The “generator output torque” in the present invention may be either “generator output actual torque” or “generator output estimated torque”. The “operation amount of the output torque of the generator” in the present invention is synonymous with or substantially synonymous with “power point”, “operating point”, and “control point”.

  Such a power generation apparatus according to the present invention includes a torque addition control unit that causes the output torque of the generator to follow the fluctuation of the turbine torque, and actively changes the rotational speed so as to match the change in the flow velocity. Rather than (sweep), change the output torque of the generator so that it is as close as possible to the turbine torque value that has changed with the change in flow velocity, and hill-climbing so that the output torque becomes the maximum power point It is included in the manipulated variable of the output torque of the generator determined by the above. In other words, the power generation device according to the present invention does not follow the transient maximum power point by following the rotational speed to the rapidly changing flow velocity fluctuation, but apparently the flow velocity around the middle center of the flow velocity waveform including the flow velocity fluctuation ( This is based on the technical idea of following the maximum power point with respect to (average flow velocity). When control is performed to follow the transient maximum power point by following the rotational speed following a sudden change in the flow velocity, inertia (rotational moment of inertia of the rotating system in the turbine and generator) is large and cannot respond. There is also a problem that the risk of losing sight is high. On the other hand, according to the torque control in the present invention that follows the maximum power point at the average flow velocity, the responsiveness and efficiency are improved, and the total power generation is also improved.

  In particular, the torque addition control by the torque addition control unit in the present invention is intended to suppress unnecessary rotational fluctuation due to insufficient responsiveness of hill climbing control, and the torque addition control itself does not follow the maximum power point, It is intended to maintain the current rotational speed. Focusing on this point, if the flow velocity fluctuation is not large, that is, if there is no steep fluctuation of the turbine torque and no unnecessary rotation fluctuation occurs, the torque addition control is not performed and the maximum power point is set by hill climbing control. It is more efficient to follow the control. Therefore, in the power generation device according to the present invention, as the torque addition control unit, when the difference between the torque detected by the turbine torque detection unit and the output torque of the generator is larger than a preset reference maximum value (upper limit threshold) or set in advance In the case where the difference is smaller than the reference minimum value (lower threshold), it is preferable to apply one having a condition determination unit that outputs the difference to add to the operation amount of the output torque of the generator determined by the hill-climbing method. .

  In the present invention, the control unit outputs a compensator that doubles the output value from the condition determination unit, and an output value from the condition determination unit that has multiplied the gain by the compensator by the maximum power point tracking control using the hill-climbing method. If it has a circuit that adds to the value, the output value from the condition judgment unit is multiplied by a predetermined gain, and the output value multiplied by the gain is used to correct the manipulated variable of the generator output torque. can do.

  Further, the torque addition control unit according to the present invention may use a difference between the current detection torque detected by the turbine torque detection unit and the detection torque detected last time, instead of the difference between the detection torque and the output torque. . That is, the point of torque addition control in the present invention is to make the generator torque quickly follow the fluctuation of the turbine torque due to the steep flow velocity fluctuation, and therefore, when the difference between the turbine torque and the generator torque occurs over a certain level. In addition, the control of applying the correction is simple and easy to understand, but if the fluctuation of the turbine torque can be grasped, the same can be achieved. Therefore, by taking the difference between the current detected torque of the turbine torque and the previously detected detected torque, the generator torque can be made to follow the fluctuation of the turbine torque quickly.

  According to the present invention, a power generator (rotational power generator) such as tidal power generation that includes a turbine that generates rotational torque by receiving external force from a fluid and a generator that generates electric power using the torque of the turbine and that cannot avoid sudden fluctuations in flow velocity or the like. Even power generators that have to take into account the inertial force of the system) can control the torque so that the generator output torque quickly follows the fluctuations in the turbine torque due to steep fluctuations in the flow velocity, etc., so that the maximum power point is reached. A power generation device can be provided.

1 is an overall schematic diagram of a tidal current power generation device according to an embodiment of the present invention. The whole block diagram of the tidal current electric power generating apparatus which concerns on the same embodiment. Explanatory drawing of the hill-climbing method control in the embodiment. The block diagram of the control part in the embodiment. The figure which shows the mode of the flow-speed fluctuation | variation in one Example of the embodiment. Explanatory drawing of the torque addition control in the Example. Explanatory drawing of the torque addition control in the comparative example of the Example. Explanatory drawing of well-known hill-climbing method control. An image of changes in general tidal current flow velocity. The figure which shows an example of the change of an actual tidal current flow velocity. The figure which expands and shows an example of the change of an actual tidal current flow velocity.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  The power generation device according to the present embodiment is a tidal current power generation device using, for example, a tidal current, and generates power using the turbine 2 installed in the sea (below the sea surface SF) and the rotational torque of the turbine 2 as shown in FIG. A generator 3 and a control unit 4 that performs maximum power point tracking control using a hill-climbing method are provided.

  The tidal current power generation device 1 is a power generation device that uses a periodic and predictable tidal current as an energy source, and is a power generation device that is low in cost and highly practical by using the pier B and a port structure.

  As shown in FIG. 1, the turbine 2 is supported by a support structure S such as a lift guide rail provided on the pier B, for example, and is configured to be lifted to the sea by a lift winch (not shown) during maintenance. In the present embodiment, the vertical shaft lift turbine 2 is applied which is less dependent on the flow direction, has a complicated tidal current disturbance, and can cope with a large pier B periphery. A plurality of turbines can be installed.

  The generator 3 converts the rotational energy of the turbine 2 into electric power, and has an input shaft connected to an output shaft of the turbine 2 via an appropriate gear 5. As the gear 5, for example, by using a non-contact power transmission mechanism that transmits power by magnetic attraction / repulsion force, the generator 3 is disposed in a casing K installed in seawater in a state of being isolated from seawater. Can do.

  Further, as shown in FIG. 2, the tidal power generator 1 according to the present embodiment includes a turbine torque detector 21 that can detect (measure and calculate) the torque (actual torque or estimated torque) of the turbine 2, and a generator. Generator output torque detector 31 capable of detecting (measuring or calculating) the output torque (actual torque or estimated torque) 3, power generation converter 6 connected to the power generator 3, and power condition connected to the power converter 6. N (hereinafter referred to as “Powercon”) 7. The turbine torque detection unit 21 and the generator output torque detection unit 31 are each configured using an appropriate instrument, circuit, or the like. The tidal power generator 1 according to the present embodiment converts the power supplied from the power generator 3 into power that can be used in a predetermined environment (home environment, factory environment, etc.) by the power generation converter 6 and the power conditioner 7 and supplies the power. The power conditioner 7 is connected to the system relay and the self-supporting relay. The power generated by tidal power generation can be supplied to the system via the transformer when the system relay is in the ON state, and can be supplied to the independent load when the independent relay is in the ON state. It can also support autonomous operation.

  The control unit 4 includes a hill-climbing method maximum power point tracking control unit 41 that performs maximum power point tracking control that tracks the maximum power point of the generator 3 using the hill-climbing method, and an output from the hill-climbing method maximum power point tracking control unit 41. And a torque addition control unit 42 capable of adding an appropriate torque to the operation amount (generator output torque command) of the output torque of the generator 3 as a value.

  The hill-climbing maximum power point tracking control unit 41 performs control for automatically obtaining a maximum power point that is a product of an optimum current and voltage that can maximize the output when the generator 3 generates power. The hill-climbing method maximum power point tracking control unit 41 according to the present embodiment changes the operation amount of the output torque of the generator 3 and operates the output torque of the next generator 3 based on the comparison result of the power values before and after the change. Specifically, as shown in FIG. 3, the turbine torque (turbine output in the figure) increases from the previous value, and the rotational speed of the generator 3 increases from the previous value. If the turbine torque is lower than the previous value and the rotational speed of the generator 3 is lower than the previous value (FIG. (Iv)), the generator When the operation amount of the output torque 3 (generator output torque command) is decreased, the turbine torque increases from the previous value, and the rotational speed of the generator 3 decreases from the previous value ((ii) in the figure). ), Or the turbine torque has decreased from the previous value, and the rotational speed of the generator 3 When it is higher than the previous value ((iii) in the figure), the control for increasing the operation amount of the output torque of the generator 3 (synonymous with generator output torque command, operating point, power point, control point) is performed. Is what you do.

  As an input factor to the hill-climbing method maximum power point tracking control unit 41, at least one of the turbine rotation speed and the generator rotation speed, and at least one of the turbine power generation amount, the generator power generation amount, the turbine torque, and the inverter output current are used. A combination with one can be mentioned. In this embodiment, the input factor to the hill-climbing maximum power point tracking control unit 41 is set to the turbine speed and the turbine power generation amount (see FIG. 2).

  Here, the curve (characteristic curve) representing the characteristics of the turbine torque and the rotational speed (rotational speed) shown in FIG. 3 changes depending on various conditions. As a result, the characteristic curve changes with time.

  Therefore, the tidal current power generation device 1 according to the present embodiment performs the torque addition control described below to complement the maximum power point tracking control by the hill-climbing method, and thus when the characteristic curve changes frequently. Is set to follow the maximum power point.

  As shown in FIGS. 2 and 4, the torque addition control unit 42 uses a hill-climbing method to calculate the torque including the difference between the detected torque and the output torque of the generator 3 when the torque detection process is executed by the turbine torque detection unit 21. This can be added to the operation amount of the generator output torque determined by the above. The control unit 4 of this embodiment includes a condition determination unit 43 and a compensator 44.

As shown in FIG. 4, the condition determination unit 43 has an upper limit threshold A (which is arbitrarily determined by a difference ΔT between the detected torque (turbine torque) and the generator output torque when the torque detection processing is executed by the turbine torque detection unit 21. If A> 0), the difference ΔT _A is output, and if the difference ΔT between the turbine torque and the generator output torque is smaller than the arbitrarily defined lower threshold B (B <0), the difference ΔT _B is output. When the difference ΔT between the turbine torque and the generator output torque is “A>ΔT> B”, 0 (zero) is output. The upper threshold and the lower threshold are values set in consideration of appropriate conditions and the like.

As shown in FIG. 4, the compensator 44 multiplies the value output from the condition determination unit 43 by a predetermined gain value. A compensator difference [Delta] T of the generator output torque and detection torque (turbine torque) to gain multiple for the difference [Delta] T _A when the upper threshold value A (A> 0) is greater than the difference between the generator output torque and torque [Delta] T May be separately provided with a compensator for multiplying the difference ΔT _B by a gain when the value is smaller than the lower threshold B (B <0), or a common compensator 44 as shown in FIG. Good. Further, when the compensators are provided separately, the gain values (correction values) in the respective compensators can be set to the same value or different from each other.

  The control unit 4 of this embodiment includes a circuit 45 that adds (adds) the output value from the condition determination unit 43 gain multiplied by the compensator 44 to the output value from the hill-climbing maximum power point tracking control unit 41. ing. Therefore, according to the control unit 4 of the present embodiment, the output value from the condition determination unit 43 is multiplied by a predetermined gain value by the compensator 44, and the maximum power of the hill-climbing method is obtained using the output value multiplied by the gain. The operation amount of the generator output torque that is the output value from the point tracking control unit 41 can be corrected. When the difference ΔT between the turbine torque and the generator output torque is “A> ΔT> B”, the output value from the condition determination unit 43 is “0 (zero)”, and therefore the hill-climbing maximum power point tracking is performed. The output value itself from the control unit 41 becomes the operation amount of the generator output torque.

  Next, of the torque control of the tidal current power generator 1 according to the present embodiment, particularly the torque addition control will be described with reference to FIGS.

  In FIG. 5, as a schematic example, the flow rate that was “flow rate A” at the time of “time 1” is changed to “flow rate C (flow rate faster than flow rate A) as“ time 1 ”to“ time 2 ”elapses. ) ”And fluctuates from“ flow velocity C ”to“ flow velocity B (flow velocity faster than flow velocity A and slower than flow velocity C) ”as“ time 2 ”to“ time 3 ”elapse. The flow rate changes from “flow rate B” to “flow rate A” with the passage of “time 4”.

  The characteristics of the turbine torque and the rotational speed vary depending on the flow velocity. As shown in FIG. 6A, the flow velocity A, the flow velocity B, and the flow velocity C are different from each other. Get higher.

  As shown in FIG. 6 (a), when the power point W1 at the start of control (first power point W1) is slightly lower than the maximum power point WX (maximum power point WX at the time of “flow rate A”), When the flow velocity changes from “flow velocity A” to “flow velocity C” with the passage of “time 1” to “time 2”, the control unit 4 of the tidal current power generation device 1 according to the present embodiment “characteristics at the flow velocity C”. ”Is executed to add a difference between the power point W1 and the turbine torque at the“ flow velocity C ”at the same rotational speed as the power point W1 that can be grasped from“ W1 ”. That is, the control unit 4 in the present embodiment uses the condition determination unit 43 of the torque addition control unit 42 to determine the turbine torque immediately before “time 2” (the turbine torque at the time “time 1” in this embodiment) and the generator. It is determined that the output torque difference is larger than the arbitrarily set upper limit threshold value, the torque difference is output, and the output value from the condition determination unit 43 multiplied by the gain by the compensator 44 is used as the hill-climbing maximum power point. The output value from the follow-up control unit 41 is added and output as an operation amount of the generator output torque. Thereby, the control point (generator output torque command value) which is a power point moves from W1 to W2 shown in FIG. Since the control point W2 at that time is lower than the turbine torque at the “flow velocity C”, the control point W2 moves toward acceleration. As a result, the rotational speed at the time “time 2” is slightly higher than the time “time 1”. Further, since the number of revolutions is slightly increased, the control point W2 at “time 2” is slightly lower than the turbine torque at “flow velocity C”.

  Next, when the flow rate changes from “flow rate C” to “flow rate B” with the passage of “time 2” to “time 3”, the control unit 4 in the present embodiment, as shown in FIG. Torque control is executed to add to W2 the difference between the turbine torque at the "flow velocity B" and the power point W2 at the same rotational speed as the power point W2 that can be grasped from the "characteristic at the flow velocity B". That is, the control unit 4 in the present embodiment uses the condition determination unit 43 of the torque addition control unit 42 to determine the turbine torque immediately before “time 3” (in this embodiment, the turbine torque at the time “time 2”) and the generator. It is determined that the output torque difference is smaller than the arbitrarily set lower threshold, and the torque difference is output, and the output value from the condition determination unit 43 multiplied by the gain by the compensator 44 is used as the hill-climbing maximum power point. The output value from the follow-up control unit 41 is added and output as an operation amount of the generator output torque. Thereby, the control point (generator output torque command value) which is a power point moves from W2 to W3 shown in FIG. 6B. Since the control point W3 at that time is lower than the turbine torque at the “flow velocity B”, the control point W3 moves toward acceleration. As a result, the rotation speed at the time “time 3” is higher than that at the time “time 2”. The control point W3 at the time “time 3” is substantially equal to the turbine torque at the “flow velocity B”.

  Next, when the flow rate changes from “flow rate B” to “flow rate A” with the passage of “time 3” to “time 4”, the control unit 4 in the present embodiment, as shown in FIG. The difference between the power point W3 and the turbine torque at the “flow rate A” at the same rotational speed as the power point W3 that can be grasped from the “characteristic at the time of the flow rate A” is added to W3. That is, the control unit 4 in the present embodiment uses the condition determination unit 43 of the torque addition control unit 42 to determine the turbine torque immediately before “time 4” (in this embodiment, the turbine torque at the time “time 3”) and the generator. It is determined that the output torque difference is smaller than the arbitrarily set lower threshold, and the torque difference is output, and the output value from the condition determination unit 43 multiplied by the gain by the compensator 44 is used as the hill-climbing maximum power point. The output value from the follow-up control unit 41 is added and output as an operation amount of the generator output torque. Thereby, the control point (generator output torque command value) which is a power point moves from W3 to W4 shown in FIG. 6C. At that time, the control point W4 is substantially the same as the turbine torque at the “flow velocity A” and the rotational speed is stagnant, so the control point W4 moves to the control point W4 at “time 4” with the same rotational speed (rotational speed). To do.

  As a result of executing such torque control, the control point W4 at the time “time 4” is closer to the maximum power point WX of the “flow velocity A” than the control point W1 at the time “time 1”. That is, in the tidal current power generation device 1 according to the present embodiment, the difference between the control point W1 and the turbine torque at the time “time 1” is not ignored, and the control including the torque including the difference is performed. At “time 2”, the control point W2 approaches the turbine torque of “flow velocity C”, which is the current flow velocity, and at “time 3”, the control point W3 is the turbine of “flow velocity B”, which is the current flow velocity. It approaches the torque further and becomes substantially equal, and at time “time 4”, the control point W4 approaches the maximum power point WX of “flow velocity A”, which is the flow velocity at that time. From the above, it can be confirmed that in the tidal current power generation apparatus 1 installed in an environment in which the flow velocity changes from moment to moment, the control unit 4 of the present embodiment performs torque control that follows the maximum power point.

  For example, when the flow rate remains “flow rate A” from “time 1” to “time 2” or changes from “flow rate A” to a flow rate within a predetermined range, the control unit 4 in the present embodiment. In the condition determination unit 43 of the torque addition control unit 42, the difference between the turbine torque immediately before “time 2” (in this embodiment, the turbine torque at the time “time 1”) and the generator output torque is arbitrarily set. The torque difference “0 (zero)” is output when it is determined that the condition is equal to or lower than the upper threshold and equal to or higher than the lower threshold. As a result, the output value from the condition determination unit 43 multiplied by the gain by the compensator 44 is also “0 (zero)”, and the control unit 4 uses the output value itself from the hill-climbing maximum power point tracking control unit 41 as the generator. Output as output torque manipulated variable. Thereby, the control point (generator output torque command value) which is a power point moves from W1 shown in FIG. 6A toward the maximum power point WX (not shown). From the above, it can be understood that the tidal current power generation apparatus 1 of the present embodiment can perform torque control that follows the maximum power point even when the flow velocity does not change or when the flow velocity changes within a predetermined range.

<Comparative example>
Next, a case (comparative example) in which torque control different from the torque control according to the above-described embodiment is performed will be described with reference to FIG. The change in flow velocity with time and the power point W1 at the start of control are the same as in the above-described embodiment.

  In this comparative example, the difference between the turbine torque of “flow velocity A” at the time “time 1” and the turbine torque of “flow velocity C” at the time “time 2” is added to the power point W1 at the start of control. Execute torque control. Then, the control point (generator output torque command value) at the time “time 2” moves from W1 to W20 as shown in FIG. Since the control point W20 at that time is lower than the turbine torque of “flow velocity C”, the control point W20 moves toward acceleration. As a result, the rotational speed at the time “time 2” is slightly higher than the time “time 1”. In addition, the difference between the control point W1 at the time “time 1” and the turbine torque at the “flow velocity A” is directly reflected in the control point W20 at the time “time 2” as an offset. The difference between the control point W20 at the time “time 2” and the turbine torque at “flow velocity C” is larger than the difference between the control point W2 and the turbine torque at “flow velocity C” shown in FIG. spread.

  Next, when the flow rate changes from “flow rate C” to “flow rate B” with the lapse of “time 2” to “time 3”, in this comparative example, as shown in FIG. Torque control is performed to add the difference between the turbine torque at “flow velocity C” at the time point “3” and the turbine torque at “flow velocity B” at the time point “time 3” to the control point W20. Then, the control point at the time “time 3” moves from W20 to W30 as shown in FIG. 7B. Since the control point W30 at that time is lower than the turbine torque of “flow velocity B”, the control point W30 moves toward acceleration. As a result, the rotation speed at the time “time 3” further increases. Also, the difference between the control point W20 at the time “time 2” and the turbine torque at the “flow velocity C” at the time “time 2” is reflected as it is as an offset in the control point W30 at the time “time 3”. Thus, the difference between the control point W30 at the time “time 3” and the turbine torque at “flow velocity B” is the difference between the control point W3 at the time “time 3” and the turbine torque at “flow velocity B” in the above-described embodiment. Spread more than the difference.

  Next, when the flow rate changes from “flow rate B” to “flow rate A” with the passage of “time 3” to “time 4”, in this comparative example, as shown in FIG. The control is executed to add the difference between the turbine torque at “flow velocity B” at the time “and the turbine torque at“ flow velocity A ”at“ time 4 ”to the control point W30. Then, the control point at the time “time 4” moves from W30 to W40 as shown in FIG. Since the control point W40 at that time is lower than the turbine torque of “flow velocity A”, the control point W40 moves toward acceleration. As a result, the rotation speed at the time “time 4” further increases. In addition, the difference between the control point W30 at the time “time 3” and the turbine torque at the “flow velocity B” at the time “time 4” is reflected as an offset in the control point W40 at the time “time 4”. Thus, the difference between the control point W40 at "time 4" and the turbine torque at "flow rate A" is the difference between the control point W4 at "time 4" and the turbine torque at "flow rate A" in the above-described embodiment. Spread more than the difference.

  Then, as shown in FIG. 7C, the control point W40 at the time “time 4” is farther from the maximum power point WX of the flow velocity A than the control point W1 at the time “time 1”. Yes. That is, according to this comparative example, the maximum power point is obtained by performing the control to add the torque while ignoring the difference between the control point W1 at the time “time 1” and the turbine torque at the “flow velocity A”. It can be understood that the following control is not implemented.

  As described above, in the tidal current power generation device 1 according to this embodiment, the control unit 4 calculates the difference between the detected torque and the output torque of the generator 3 when the turbine torque detection unit 21 executes the torque detection process. The torque addition control part 42 which can add the including torque to the operation amount of the output torque of the generator 3 determined by the hill-climbing method is provided. Further, the torque addition control itself by the torque addition control unit 42 does not follow the maximum power point, and is a control for maintaining the current rotational speed by utilizing the fact that the rotational speed does not change even if the torque is changed. Therefore, according to the tidal current power generation device 1 according to the present embodiment, the turbine after changing with the change in flow velocity is not actively changed (sweep) so as to match the change in flow velocity. By changing the output torque of the generator 3 so as to be as close as possible to the torque value, and correcting the output value of the hill-climbing control to make a fine adjustment, in addition to the flow rate fluctuation, the delay of the rotation speed of the turbine 2 and the generator 3 Torque that avoids losing sight of the maximum power point due to fluctuations in turbine torque due to fluctuations, suppresses unnecessary rotation fluctuation due to insufficient responsiveness of hill climbing control, and follows the maximum power point It is possible to realize a control.

  The torque control employed in the tidal current power generation device 1 according to the present embodiment simply adds the torque difference with respect to the input fluctuation to the control operation amount (the output torque command value of the generator 3) as it is. There is no need to tabulate a large amount of data, and this is simple control that causes the output torque of the generator 3 to follow the fluctuation of the turbine torque.

  In particular, in the tidal current power generation device 1 according to the present embodiment, the torque addition control unit 42 determines that the difference between the torque detected by the turbine torque detection unit 21 and the output torque of the generator 3 is greater than a preset reference maximum value (upper threshold). And a condition determining unit 43 that outputs the difference to the manipulated variable of the output torque of the generator 3 determined by the hill-climbing method when the value is larger or smaller than a preset reference minimum value (lower threshold). Therefore, when the flow velocity fluctuation is not large, that is, when there is no steep fluctuation in the turbine torque and no unnecessary rotation fluctuation occurs, the maximum power point can be tracked only by hill-climbing control. Realizes maximum power point tracking control with high performance.

  In addition, this invention is not limited to embodiment mentioned above. For example, “the detected torque when the torque detection process is executed by the turbine torque detector” may be either “actual turbine torque” or “estimated turbine torque”.

  Similarly, the “generator output torque” in the present invention may be “generator output actual torque” or “generator output estimated torque”.

  The torque control of the power generation device according to the present invention is not limited to the tidal current power generation device, but can be applied to the torque control of the ocean current power generation device, the wave power generation device, the ocean temperature difference power generation device, the tidal power generation device, and the wind power generation device. It is possible to follow the maximum power point by executing the torque addition control of the present invention also in each of the rotating power generators.

  Further, the torque addition control unit may use a difference between the current detection torque detected by the turbine torque detection unit and the detection torque detected last time, instead of the difference between the detection torque and the output torque. That is, the point of torque addition control in the present invention is to cause the generator torque to quickly follow the fluctuation of the turbine torque due to the steep flow velocity fluctuation, and therefore, when the difference between the turbine torque and the generator torque occurs over a certain level. In addition, the control of applying the correction is easy to understand, but if the fluctuation of the turbine torque is known, the same can be achieved. Therefore, by taking the difference between the current detected torque of the turbine torque and the previously detected detected torque, the generator torque can be made to follow the fluctuation of the turbine torque quickly.

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1 ... Power generator (tidal power generator)
2 ... Turbine 21 ... Turbine torque detection unit 3 ... Generator 4 ... Control unit 42 ... Torque addition control unit 43 ... Condition judgment unit 44 ... Compensator

Claims (4)

A turbine that generates rotational torque in response to external force from the fluid;
A generator for generating power by the torque of the turbine;
A turbine torque detector for detecting an actual torque or an estimated torque of the turbine;
A control unit that performs maximum power point tracking control using a hill-climbing method that changes the operation amount of the output torque of the generator and determines the operation amount of the next output torque based on the comparison result of power values before and after the change. And
The controller is
Torque including the difference between the detected torque and the output torque of the generator at the time when the torque detection process is executed by the turbine torque detector can be added to the operation amount of the output torque of the generator determined by the hill climbing method. A power generation apparatus comprising a torque addition control unit. When the difference between the detected torque by the turbine torque detector and the output torque of the generator is larger than a preset reference maximum value or smaller than a preset reference minimum value, the torque addition control unit is The power generation device according to claim 1, further comprising a condition determination unit that outputs the difference to be added to an operation amount of the output torque of the generator determined by the hill climbing method. The control unit includes a compensator that multiplies the output value from the condition determination unit, and an output value from the condition determination unit that has multiplied the gain by the compensator by maximum power point tracking control using the hill-climbing method. The power generation device according to claim 2, further comprising a circuit that adds to the output value. The torque addition control unit uses a difference between a current detection torque detected by the turbine torque detection unit and a detection torque detected last time, instead of the difference between the detection torque and the output torque. 3. The power generation device according to 3.

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