WO2019117114A1 - Hydroelectric system and control method - Google Patents

Abstract

Provided is a hydroelectric system capable of being controlled such that appropriate power should be output without previous measurement; of resuming, even when becoming a stalled state, to a normal power generating state from the stalled state to obtain large generated power, and of preventing hunting in which on/off of power control is repeated. The hydroelectric system comprises: a water wheel (1); a generator (3); and a control device (4). The control device (4) performs basic control by basic control means for performing MPPT control and the like. On the basis of a stall boundary condition (D) prescribed by an output power value and a rotation number value, the output power of the generator (3) is controlled as necessary such that the maximum power is obtained in the range where the water wheel (3) is not determined to be in the stalled state. In the stall boundary condition D, a stall boundary region is configured as a hysteresis region.

Description

HYDRO POWER GENERATION SYSTEM AND CONTROL METHOD Related application

This application claims the priority of Japanese Patent Application No. 2017-238255 filed on Dec. 13, 2017, which is incorporated by reference in its entirety.

The present invention relates to a hydroelectric power generation system and control method for preventing a hydroelectric power generator from stalling and obtaining a large amount of generated power.

A hydroelectric generator is a system that uses kinetic energy of flowing water for power generation. The hydroelectric power generation device mainly includes: a water turbine that receives a flow of water; a generator that is connected to the water turbine and converts the rotation energy into electrical energy; and a controller that controls the output of the generator and the water turbine. Prepare.

Since the power extracted from the generator changes with the flow velocity, the controller measures the flow velocity, the rotational speed of the water turbine, or the generated voltage of the generator to determine the optimal power extracted from the generator, and generates the power of the generator. Control to match the power and the optimum value.

For this purpose, it is necessary to install a hydroelectric generator in the water channel in advance, measure the flow velocity, the generated power, and the power generation characteristics, set optimum values, and create the table characteristics by a control map or the like. Therefore, cost increase factors such as measurement work occur until the operation of the hydroelectric system.

In order to eliminate the prior measurement and the setting operation of the optimum value, there has been proposed a method of controlling hydroelectric power generation by maximum power point tracking control called MPPT control according to hill climbing or the like (for example, Patent Document 1). MPPT control is also used in wind power generation (for example, Patent Document 2).

JP, 2016-185006, A Unexamined-Japanese-Patent No. 2010-200533

However, it may be difficult to apply the MPPT control to the hydroelectric power generation control device, since the rotational speed of the water turbine may decrease and the power generation may also decrease.

In the Patent Document 2, although MPPT control in wind power generation, control to cope with a stall is proposed. That is, every time when the optimum operating point of the generator is sought by MPPT control, the time derivative of the output voltage or the time derivative of the output current is calculated, and the output power at the operating point and the time derivative of the calculated output power Stall is determined based on whether or not the relation of (1) satisfies the stall boundary condition. When it is determined that a stall occurs, the load on the generator is released or reduced.

However, when the stall boundary condition is not satisfied by releasing or reducing the generator load, when the load returns to the original value, the stall boundary condition is immediately met, and the power limit is turned on and off. Hunting may occur, which is repeated.

The present invention solves the above-mentioned problems, and an object thereof is to perform appropriate output power control without performing prior measurement, and to restore from a stall state to a normal power generation state even when the stall state is established. It is possible to provide a hydroelectric power generation system and control method capable of obtaining a large amount of generated power and preventing hunting of power control.

Hereinafter, in order to facilitate understanding, for convenience, reference will be made to the reference numerals of the embodiments.

The hydroelectric power system according to the present invention includes a water turbine 1 rotating in water, a generator 3 for converting the rotational energy of the water turbine 1 into electrical energy, and the output power of the generator 3 to adjust the rotational speed of the water turbine 1. A hydroelectric power generation system comprising a control device 4 for controlling
The control device 4 is
Output power detection means 16 for detecting the output power value of the generator 3;
Output power storage means 17 for storing the detected output power value;
Rotation speed detection means 18 for detecting the rotation speed of the generator 3;
Rotation speed storage means 19 for storing the detected rotation speed;
Basic control means 13 for controlling the output power of the generator using the stored output power value and the rotational speed;
A stall boundary condition D for the output power value and the rotational speed value, as needed, so as to obtain the maximum power within a range in which the water turbine is not determined to be in a stall state based on a previously set stall boundary condition D A generation power limit control unit 20 for limiting the output power of the generator 3;
In the stall boundary condition D, determination curves a and b indicating the relationship between the output power value and the rotation speed value, a stall determination region A determined to be a stall condition and a non-stall determination region B determined to be a non-stall condition. The judgment curves a and b are divided by the judgment curves a and b for judging as a stall condition when the output power value used by the basic control means 13 increases and / or the rotation speed value decreases. And a return determination curve b for determining a non-stall state when the output power value used by the basic control means 13 decreases and / or when the rotational speed value increases. A stall boundary area C is configured as a hysteresis area between them.

According to this configuration, the control device 4 basically monitors the generated power and the like, and controls the number of rotations of the water turbine 1 by controlling the output power in accordance with a defined control rule. During this time, the generated power limit control means 20 limits the output power of the generator 3 as necessary so that the maximum power in the range in which the water turbine is not determined to be in a stall state in light of the stall boundary condition D is obtained. Since the stall boundary area C is provided as the hysteresis area in the stall boundary condition D, hunting which is a repeated on / off state of the stall determination by the generated power limitation control means 20 is prevented, and power limitation can be performed stably.

The basic control means 13 is an MPPT control means 13 for controlling the maximum power operating point following the output fluctuation of the generator 3, and the generated power limit control means 20 is a control cycle of the MPPT control means 13. The stall state or non-stall state of the water turbine 1 may be determined each time, and the output power of the generator may be limited as necessary.

According to the MPPT control in which the maximum power operating point is followed and controlled, efficient power generation can be performed even if the preliminary measurement work of the flow velocity and the turbine rotational speed at the site where the turbine 1 is installed is omitted. However, when the MPPT control is applied to the hydroelectric power generation system, the rotational speed of the water turbine 1 may be reduced and the generated power may also be reduced only by the control, and the normal state may not be restored. According to this configuration, the stall determination is performed by the generated power restriction control means 20, and the output power is limited at the time of stall, so that the stall state can be recovered and the generated power reduction due to the stall does not occur largely. , MPPT control can be performed efficiently.

The control device 4 includes PWM control means 15 for performing PWM control of the output power of the generator 3, and the MPPT control means 13 performs the PWM such that the generator 3 becomes the output power of the maximum power operating point. A duty ratio (R _Duty1 ) is given to the control means 15, and the generated power restriction control means 20 is a duty ratio obtained by subtracting a predetermined duty ratio (R Duty ₂ ) from the duty ratio (R _Duty1 ) given from the MPPT control means 13. The output power may be limited by operating the PWM control means 15 at (R _Duty1 -R _Duty2 ).

In the case of this configuration, it is possible to limit the output power of the generator 3 with the maximum power within the range that is not determined to be a stall by simple control.

The control method of a hydroelectric power generation system according to the present invention includes a hydraulically rotating water turbine 1, a generator 3 for converting rotational energy of the water turbine 1 into electric energy, and adjustment of output power of the generator 3 to rotate the water turbine 1 A method of controlling a hydroelectric power system comprising a controller 4 for controlling the number of
Setting a stall boundary condition D with respect to the output power value of the generator 3 and the rotation value of the water turbine 1,
As the basic control by the control device 4, using the output power value of the generator 3 and the rotational speed of the water wheel 1, the output power of the generator 3 is controlled according to a defined rule,
A range in which the water turbine is not determined to be in a stall state based on the stall boundary condition D from the output power value of the generator 3 and the rotation value of the water turbine 1 in each control cycle of the basic control of the control device 4 To limit the output power of the generator 3 as needed to achieve the maximum power at (S7),
In the stall boundary condition D, determination curves a and b indicating the relationship between the output power value and the rotation speed value, a stall determination region A determined to be a stall condition and a non-stall determination region B determined to be a non-stall condition. The judgment curves a and b are divided by the judgment curve a judged as a stall state when the output power value increases and / or the rotation speed value decreases, and the output power value decreases And a return determination curve b which is determined to be in a non-stall state when the rotation speed value increases, and a stall boundary area C is formed as a hysteresis area between the curves a and b.

According to this configuration, as described above for the hydroelectric power generation system, even when a stall state occurs, the normal power generation state can be restored, and it is possible to obtain large generated power. Further, since the stall boundary region C of the hysteresis region is provided, hunting of the power control by the stall determination is prevented.

The control device 4 performs, as the basic control, an MPPT control that follows and controls the maximum power operating point with respect to the output fluctuation of the generator 3, and the output of the generator 3 for each control cycle of the MPPT control. Based on the stall boundary condition, the output power of the generator 3 is limited as necessary from the power value and the rotation numerical value of the water turbine 1 based on the stall boundary condition so that the water turbine has maximum power in a range not determined to be a stall condition. May be

According to MPPT control, efficient power generation can be performed even if advance measurement work of the flow velocity and turbine rotation speed at the site is omitted, but it is not possible to return to the normal state when it is stalled by only that control. There is a case. In this configuration, according to this configuration, the output power of the generator 3 is limited by the maximum power within the range not determined as stall due to the stall boundary condition, so that efficient generation by MPPT control does not occur. Control can be performed.

Any combination of the at least two configurations disclosed in the claims and / or the description and / or the drawings is included in the present invention. In particular, any combination of two or more of the claims is included in the present invention.

The invention will be more clearly understood from the following description of the preferred embodiments with reference to the accompanying drawings. However, the embodiments and the drawings are for the purpose of illustration and description only and are not to be taken as limiting the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in multiple drawings indicate the same or corresponding parts.
BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing which shows the outline of the hydraulic power generation system which concerns on one Embodiment of this invention. It is a block diagram which shows the conceptual structure of the hydraulic power generation system of FIG. It is a stall threshold value control graph which becomes a reference example of a stall judging field and a non-stall judging field. It is the stall threshold value control graph which shows the stall determination area | region used by the hydraulic power generation system of FIG. 1, a non-stall determination area | region, and a stall boundary area | region. It is a flowchart which shows the procedure of the control method which the hydraulic power generation system of FIG. 1 performs. It is a schematic explanatory drawing of the other example of the hydraulic power generator used with the hydraulic power generation system of FIG.

An embodiment of the present invention will be described with reference to the drawings. This hydroelectric power generation system is an example of a horizontal axis (propeller type) hydroelectric generator. The water turbine 1 is rotated by the kinetic energy of the water flowing through the water channel (not shown), and the main shaft 2 of the water turbine 1 rotates the generator 3. The generator 3 is a three-phase synchronous generator using, for example, a permanent magnet, and is connected to the main shaft 2 by a coupling (not shown) or the like. A speed increaser 25 may be provided between the main shaft 2 and the generator 3 as in the example of FIG.

When a load is connected to the generator 2 to consume the output, torque is applied to the water turbine 1 from the generator 3, and the rotation of the water turbine 1 is braked. When the load power is increased, the rotation speed of the water wheel 3 is decreased, and when the load power is decreased, the rotation speed of the water wheel 3 is increased. A load circuit 5 is connected as a load of the generator 3 via the control device 4. The control device 4 increases or decreases the torque of the generator 3 according to the flow velocity, and controls the water turbine to rotate at an optimal rotation speed. A DC / DC converter, an inverter or the like is used for the control device 4. The load circuit 5 is an electrical device or a load system.

FIG. 2 shows a specific example of the control device 4. The control device 4 includes a main circuit unit 6 that supplies the generated power of the generator 3 to the load circuit 5 and a control circuit unit 7 that controls the main circuit unit 6 and further includes a battery 8 that stores the generated power. ing. The main circuit unit 6 includes a rectifier 9, a converter 10, an ammeter 11, a voltmeter 21, and a switching unit 12 sequentially interposed between the battery 8 and the generator 3.

The rectifier 9 is a device that rectifies the three-phase AC power generated by the generator 3 into a direct current, and is configured by a half bridge circuit of a semiconductor switching element. Converter 10 comprises, for example, a boost chopper. Alternatively, converter 10 may be a buck chopper. The switching means 12 is means for switching the output power supplied to the battery 8 by turning on and off the DC power subjected to the rectification. The switching means 12 may be a semiconductor switching element or a contact switch. The switching means 12 can be switched on and off by a control signal output from the PWM control means 15.

The battery 8 and the load circuit 5 are in parallel, and can charge the load circuit 5 while charging the power generated by the generator 3 to the battery 8. In the main circuit unit 6, the battery 8 and the load circuit 5 are connected in parallel to the output side of the generator 3, so the output voltage becomes substantially constant. Therefore, the output power of the generator 3 can be adjusted by adjusting the duty ratio of the output current of the converter 10 by opening and closing the switching means 12.

The control circuit unit 7 is composed of a computer or the like, and in this example, performs normal control by the MPPT control means 13 which is a basic control means, and controls the stall of the water turbine 1 by the stall correspondence control means 14. The MPPT control means 13 and the stall correspondence control means 14 both open and close the switching means 12 by pulse width control by the PWM control means 15. That is, the duty ratio, which is the ratio of the closing time to the sum of the opening time and the closing time, is controlled. This adjusts the output power. The control circuit unit 7 may perform normal control by basic control means that adopts a control method different from the MPPT control means 13.

The MPPT control means 13 changes the operating point of the generator 3 so as to always follow the maximum output operating point in control with respect to the fluctuation of the output power of the generator 3, thereby the maximum output from the generator 3 It is a means to control taking out. The maximum output operating point is an operating point at which the output to the load circuit 5 is maximum among the operating points obtained for each sampling by the MPPT control means 13. The power at the operating point is detected from the measurement values of the ammeter 11 and the voltmeter 24.

The stall control unit 14 has an output power detection unit 16, an output power storage unit 17, a rotation number detection unit 18, a rotation number storage unit 19, and a generated power limitation control unit 20. The stall handling control means 14 collates the stall boundary condition D with the generated power limit control means 20 every time the MPPT control means 13 searches for the operating point, and limits the output power when it is determined to be a stall. .

The output power detection means 16 is a means for detecting the output power value of the generator 3. The output power detection means 16 takes in, for example, the current value detected by the ammeter 11 and the voltage value detected by the voltmeter 21, and calculates a value obtained by multiplying the current value by the voltage value to obtain an output power value. . The voltage value is the voltage value of the battery 8. A power meter (not shown) may be provided and detected. The output power storage unit 17 stores the output power detected by the output power detection unit 16. The output power value to be stored is updated each time the output power detection means 16 performs power detection.

The rotational speed detection means 18 takes in a detection output by a pulse or the like of a rotational detector (not shown) provided in the generator 3 and calculates the rotational speed of the generator 3 or the like to obtain the rotational speed of the generator 3 To detect The number of rotations is the number of rotations per unit time, in other words, the rotation speed. The rotation detector may be provided anywhere as long as it can output a detection value that can be converted to the rotation speed of the generator 3. The rotation speed storage unit 19 stores the rotation speed detected by the rotation speed detection unit 18. The stored rotational speed is updated each time the rotational speed detection means 18 detects the rotational speed.

A stall boundary condition D for the output power value and the rotational speed value is preset. The generated power restriction control means 20 collates the output power stored in the output power storage means 17 and the rotational speed stored in the rotational speed storage means 19 with the stall boundary condition D. That is, the stored output power and rotational speed are applied to the stall boundary condition D. Based on the stall boundary condition D, the generated power limit control means 20 limits the output power of the generator 3 to the maximum power in the range not determined to be a stall. The limitation of the output power is performed by decreasing the duty ratio controlled by opening and closing the switching means 12 by the PWM control means 15.

As the stall boundary condition D, as shown in FIG. 4, a judgment curve a showing the relationship between the output power value and the rotation value, the stall judgment region A judged to be stalled and the non-stall judgment region B judged to be non-stall. , B. In the judgment curves a and b, when the output power value increases and / or when the rotational speed value decreases, a stall judgment curve a determined for judging as stall, and when the output power value decreases and / Alternatively, it includes a return judgment curve b which is determined to determine that the engine is not stalled when the rotation speed value is increased. A stall boundary region C of the hysteresis region is a region between the two curves a and b.

The control operation of the control circuit unit 7 of FIG. 2 will be described with reference to FIG. The control process of FIG. 6 is repeated each time the MPPT control means 13 goes for the operating point.

In the rotational speed calculation process (S1), the rotational speed N of the generator 3 is calculated by the rotational speed detection means 18, and this is used as a detection value of the rotational speed. In the power calculation process (S2), the output power detection means 16 calculates the output power value P of the generator 3 and uses it as a detection value of the output power. In each of the rotation speed storage process (S3) and the power storage process (S4), the detected rotation speed N and output power value P are stored in the rotation speed storage means 19 and the output power storage means 17, respectively. The calculations (S1, S2) of the rotational speed and the power may be performed first.

Thereafter, in the MPPT control process (S5), the MPPT control means 13 calculates the MPPT control from the stored rotational speed N and output power value P to obtain the maximum power Pmax which is the optimum power. In the control process (S6), the duty ratio R _Duty1 that _{gives the} maximum power Pmax is calculated.

In the generation power limit control process (S7), the rotational speed N and the output power value P detected and stored by the generation power limit control means 20 are defined as stall boundary conditions D defined by the stall threshold control graph of FIG. Then, it is determined whether or not the engine is in a stall condition, and if it is in a stall condition, a command to limit the output power is output.

The PWM control process (S8) basically controls the output power by the PWM control by the PWM control unit 15 with the duty ratio R _Duty1 instructed from the MPPT control unit 13. If it is determined in the generated power restriction control process (S7) that the vehicle is in a stalled state, the duty ratio of PWM control is reduced. Specifically, the duty ratio R _Duty used in PWM control step (S8), the current duty ratio R _Duty1 of PWM control, the duty ratio R _Duty1 -R _Duty2 obtained by subtracting only the duty ratio R _Duty2 for subtraction. The duty ratio R _Duty2 for subtraction is calculated in comparison with the stall threshold control graph of FIG. 4. For example, the duty ratio R _Duty2 for subtraction is obtained by comparing the output power value with the power value at the rotational speed N in the determination curve a and / or b of the stall threshold value control graph of FIG. 4.

How to use the stall threshold control graph in the generation power limit control process will be described.
The power threshold upper limit Pa and the power threshold lower limit Pb corresponding to the measured output power current value Ppv [W] and the rotation speed Npv [rpm], and the rotation speed current value Npv in the stall threshold control graph of FIG. The output power Ppv is compared to determine R _{Duty 2} .

(1) When Ppv of (power measurement value)> Pa (threshold limit) R _Duty = R _Duty1 -R _Duty2
However, R _{Duty 2} is a preset control constant value such as 3%.
(2) when R _Duty = R of Ppv (power measurement value) = Pa (threshold limit) _Duty1 -R _Duty2
However, R _Duty 2 is a preset control constant value such as 2%.
(3) When Pa (threshold upper limit)> Ppv (power measurement value)> Pb (threshold lower limit),
R _Duty = R _Duty1 -R _Duty2
However, R _{Duty 2} is a preset control constant value such as 1%.
(4) When Ppv (power measurement value) Pb Pb (threshold lower limit),
R _Duty = R _Duty1 -R _Duty2
However, R _Duty2 is a control constant value preset at 0%.

When the maximum power point is followed by the MPPT control by the control device 4 in the hydroelectric power generation system, the water turbine 1 may be in a stalled state, which causes a significant decrease in the generated power. On the other hand, as described above, the stall condition is determined by the generated power restriction control means 20, and the duty ratio is reduced to reduce the generated power, whereby a normal power generation state can be achieved. This makes it possible to obtain a large amount of generated power.

When the stall condition is determined as described above, if the stall determination region A and the non-stall determination region B determined to be non-stall are divided by one determination curve d as shown in FIG. Then, after the load power is reduced or released and the non-stall state is reached, there is no significant change in the flow velocity of the water flow and the like.

On the other hand, in this embodiment, as the stall boundary condition, as shown in FIG. 4, a stall determination area A for determining a stall and a non-stall determination area B for determining a non-stall have two determination curves a. , B. That is, in the judgment curve, a stall judgment curve a for determining a stall state when the output power value increases and / or the rotation speed value decreases, and when the output power value decreases and / or the rotation speed value increases. And a return determination curve b that determines that the vehicle is not in a stall state. A stall boundary area C is formed as a hysteresis area between these curves.

Whether it is judged by the stall judgment curve a or by the return judgment curve b is stored in the previous judgment (previous control cycle) using a flag etc. If the previous time is a non-stall state, the determination is made using the stall determination curve a, and if the previous time is a stall state, it is determined using the return determination curve b.

If it is determined in the previous control cycle that a stall condition has occurred, the stall condition is maintained even if it exceeds the stall determination curve a of the output power, and if it exceeds the recovery determination curve b, it is determined that the vehicle is in the non-stall condition. Therefore, hunting which is a repeated on / off state of stall determination is prevented, and control is stabilized.

As described above, although the preferred embodiments have been described with reference to the drawings, various additions, modifications or deletions can be made without departing from the spirit of the present invention. Therefore, such is also included in the scope of the present invention.

1 ... water wheel 3 ... generator 4 ... control device 13 ... MPPT control means (basic control means)
16: Output power detection means 17: Output power storage means 18: Rotational speed detection means 19: Rotational speed storage means 20: Generated power restriction control means D: Stall boundary condition

Claims (5)

With a hydraulically rotating water turbine,
A generator that converts the rotational energy of this water turbine into electrical energy,
A hydroelectric power generation system comprising a control device that adjusts the output power of the generator to control the rotational speed of the water turbine,
The controller is
Output power detection means for detecting an output power value of the generator;
Output power storage means for storing the detected output power value;
Rotation speed detection means for detecting the rotation speed of the generator;
Rotation speed storage means for storing the detected rotation speed;
Basic control means for controlling the output power of the generator using the stored output power value and the rotational speed;
The power generation is performed as needed so that the maximum power is in a range in which the water turbine is not determined to be in a stall state based on a stall boundary condition for the output power value and the rotation speed value, which is set in advance. Power generation control means for limiting the output power of the
In the stall boundary condition, a stall determination area determined to be a stall state and a non-stall determination area determined to be a non-stall state are classified by a determination curve indicating the relationship between the output power value and the rotation speed value. The curve shows a stall determination curve for determining a stall state when the output power value used by the basic control means increases, and a non-stall state when the output power value used by the basic control means decreases. And a stall boundary area is formed as a hysteresis area between these curves.
Hydroelectric system. The hydroelectric power generation system according to claim 1, wherein the basic control means is an MPPT control means for following and controlling a maximum power operating point with respect to the output fluctuation of the generator, and the generated power restriction control means is A hydroelectric power generation system that determines a stalled state or a non-stalled state of the water turbine 1 for each control cycle of the MPPT control means, and limits the output power of the generator as necessary. The hydroelectric power generation system according to claim 2, wherein the control device comprises PWM control means for performing PWM control of the output power of the generator, and the MPPT control means is configured to output the output power of the maximum power operating point of the generator. The PWM control means is provided with a duty ratio (R _Duty1 ) so that the generated power limit control means subtracts a predetermined duty ratio (R _Duty2 ) from the duty ratio (R _Duty1 ) given by the MPPT control means. The hydraulic power generation system which limits the said output electric power by operating the said PWM control means by the duty ratio (R _Duty1- R _Duty2 ). With a hydraulically rotating water turbine,
A generator that converts the rotational energy of this water turbine into electrical energy,
A method of controlling a hydroelectric power generation system including a control device that controls the rotational speed of a water turbine by adjusting the output power of the generator.
Setting a stall boundary condition for the output power value of the generator and the rotation value of the water turbine,
As basic control by the control device, the output power value of the generator and the rotational speed of the water wheel are used to control the output power of the generator according to a defined rule,
From the output power value of the generator and the rotation value of the water turbine at each control cycle of the basic control of the control device, based on the stall boundary condition, the maximum power within a range where the water turbine is not determined to be in a stall condition Limit the output power of the generator as needed,
In the stall boundary condition, a stall determination area determined to be a stall state and a non-stall determination area determined to be a non-stall state are classified by a determination curve indicating the relationship between the output power value and the rotation speed value. The curves include a stall determination curve that is determined to be in a stall state when the output power value is increased, and a return determination curve that is determined to be in a non-stall state when the output power value is decreased. Is configured as a hysteresis region as a stall boundary region,
Control method of hydroelectric power generation system. 5. The control method of a hydroelectric power generation system according to claim 4, wherein said control device performs MPPT control for following up control of the maximum power operating point with respect to output fluctuation of said generator as said basic control, MPPT control The maximum power in the range in which the water turbine is not determined to be in a stall state based on the stall boundary condition from the output power value of the generator and the rotation speed value of the water turbine, as needed, in each control cycle A control method of a hydroelectric power generation system, which limits output power of the generator.

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