JP2016223368A - Hydraulic power generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power generation system which avoids continuous operation according to rotation speed of mechanical resonance point upon an autonomous operation.SOLUTION: A predetermined speed setting range of a motor 21 or a power generator 22 is preset based on a mechanical resonance point of a hydraulic power generation system. When a time during which the rotation speed of the motor 21 or the power generator 22 is within a predetermined speed setting range elapses continuously by a continuous operation judging time or more upon an autonomous operation, an element 27b for dynamic brake is turned on and rotation speed of the motor 21 or the power generator 22 is moved to the outside of a speed setting range. Further, when a time after the rotation speed of the motor 21 or the power generator 22 is moved to the outside of the predetermined speed setting range elapses continuously by a stop judging time or more, the element 27b for the dynamic brake is turned off.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydroelectric power generation system, and more particularly to a method of suppressing continuous operation at a mechanical resonance point of a generator.

  In the hydroelectric power generation system, a prime mover (water turbine) is connected to a generator, and mechanical energy of the prime mover (water turbine) is converted into electric energy by the generator. FIG. 13 shows a configuration example of a conventional hydroelectric power generation system.

  During the autonomous operation, the system-side switch 12 is opened and power is not supplied from the system 17 to the autonomous operation load 15, and only the electric power generated by the generator 4 is supplied to the autonomous operation load 15. At this time, the generator-side power conversion circuit 6 controls the output of the generator 4 so that the voltage of the DC circuit 7 becomes constant. In the system side power conversion circuit 8, the output voltage supplied to the self-sustained operation load 15 is controlled.

  In addition, the generator-side power conversion circuit 6 and the system-side power conversion circuit 8 often use a PWM converter that uses a self-extinguishing switching device such as an IGBT.

  On the other hand, as shown in FIG. 14, the prime mover (water turbine) 1 has a characteristic that the output changes depending on the rotation speed when the amount of water is constant. In addition, when the flow rate (water amount) of the water flow received by the prime mover (water turbine) 1 changes, the rotational speed-output characteristic curve also changes.

  Further, the output of the prime mover (water turbine) 1 is supplied to the output of the system side power conversion circuit 8 (that is, the self-sustained operation load 15) via the generator 4 and the generator side power conversion circuit 6. Therefore, the rotational speeds of the prime mover (water turbine) 1 and the generator 4 during the independent operation depend on the amount of water for turning the prime mover (turbine) 1 and the independent operation load 15.

  Patent Document 1 is disclosed as a prior art of a hydroelectric power generation system. This Patent Document 1 describes a technology related to protection when the input to the prime mover becomes excessive, and a technology related to a braking circuit (dynamic brake circuit) for regenerative power consumption. In FIG. 13, a dynamic brake circuit is constituted by the dynamic brake element 9 and the dynamic brake resistor 10.

  When regenerative power is generated, the generator-side power conversion circuit 6 and the system-side power conversion circuit 8 may rise to a DC voltage that causes overvoltage breakdown. When the DC voltage rises to a level where it is necessary to protect the device, the dynamic brake element 9 is turned on to suppress the increase of the DC voltage.

Japanese Patent No. 4595398 Japanese Patent Laid-Open No. 8-111980

  However, the hydroelectric power generation system has a rotational speed that is a mechanical resonance point at which large vibrations are generated in the prime mover 1 (water turbine) and the generator 4 due to mechanical elements such as the prime mover (turbine) 1 and the generator 4. Exists.

  On the other hand, as described above, the rotational speeds of the prime mover (water turbine) 1 and the generator 4 during the independent operation are determined by the amount of water for turning the prime mover (turbine) 1 and the independent operation load 15. Therefore, depending on the amount of self-sustained operation load, the prime mover (water turbine) 1 and the generator 4 may continuously operate at the rotational speed at the mechanical resonance point, resulting in unstable operation. If this unstable operation continues for a long time, it leads to metal fatigue of the prime mover (water turbine) 1 and the generator 4, which is not preferable.

  Patent document 2 is disclosed as a prior art which suppresses the shaft twist phenomenon in a hydroelectric power generation system. However, in this patent document 2, in a system in which an AC system fed by a generator is connected to a DC system via a thyristor AC / DC power converter, the control angle of the thyristor is controlled to an appropriate value. This technology suppresses the twisting phenomenon. This technique is not applicable when the power converter is a PWM converter made of a self-extinguishing switching device.

  Furthermore, the resonance point is suppressed by changing the control command to the power converter (the control angle of the thyristor), and the arithmetic processing increases, so that there is a problem that an arithmetic processing device capable of high-speed processing is required. There was a point.

  As described above, in the hydroelectric power generation system, it is a problem to avoid continuous operation due to the rotational speed of the mechanical resonance point during the self-sustaining operation.

  The present invention has been devised in view of the above-described conventional problems, and one aspect thereof is a prime mover rotating by a water flow, a generator connected to the prime mover, and converting output power of the generator into DC power. A power conversion circuit for generator control, a power conversion circuit for output voltage control that converts the power converted into direct current into power for supplying power to a self-sustaining operation load, and a system separated from the power conversion circuit for output voltage control And a dynamic brake circuit connected to a DC voltage section between a power converter circuit for controlling a generator and a power converter circuit for controlling an output voltage, and having a series connection of a dynamic brake element and a dynamic brake resistor And a speed detection estimating means for detecting or estimating the rotational speed of the prime mover or the generator, and opening the switch to solve the system from the power conversion circuit for output voltage control. Is a hydroelectric power generation system that supplies power output from the generator to a self-sustained operation load connected to the output of the power conversion circuit for output voltage control, and based on the mechanical resonance point of the hydroelectric power generation system, or When a predetermined speed setting range for the generator is set and the engine or the rotation speed of the generator is within the predetermined speed setting range during the self-sustained operation, the dynamic brake is applied. The time after the motor or generator is turned on to move the rotational speed of the prime mover or generator outside the predetermined speed setting range and the rotational speed of the prime mover or generator is moved outside the predetermined speed setting range is stopped. The dynamic brake element is turned off when continuously elapses for the determination time or longer.

  Further, as another aspect, a prime mover that is rotated by a water flow, a generator connected to the prime mover, a power conversion circuit for controlling a generator that converts the output power of the generator into direct current power, and the power converted to direct current are self-supporting. Power conversion circuit for output voltage control that converts power to power for operating load, switch that disconnects the system from power conversion circuit for output voltage control, power conversion circuit for generator control, and output voltage control A dynamic brake circuit that is connected to a DC circuit between the power conversion circuit and a dynamic brake element and a dynamic brake resistor connected in series, and a flow rate adjusting unit that adjusts the flow rate of the water flow input to the prime mover. A flow rate controller for controlling the flow rate adjusting means; and output power detection estimating means for detecting or estimating the output power of the generator; and opening the switch A hydroelectric power generation system that supplies power to a self-supporting load connected to the output of a power conversion device for output voltage control when the system is disconnected from the power conversion circuit for output voltage control. A predetermined output setting range is set based on the mechanical resonance point of the power generation system, and the flow rate controller performs control so that the flow rate of the water flow is constant during the independent operation, and the output power of the generator is a predetermined output during the independent operation. When the time within the set range continuously exceeds the continuous operation determination time, the dynamic brake element is turned on to move the output power of the generator out of the predetermined output range, and the output power of the generator is The dynamic brake element is turned off when the time after moving out of the output setting range continuously exceeds the stop determination time.

  According to the present invention, in a hydroelectric power generation system, it is possible to avoid continuous operation due to the rotational speed of a mechanical resonance point during self-sustaining operation.

1 is a block diagram showing a hydroelectric power generation system in Embodiment 1. FIG. The block diagram which shows the process regarding the dynamic brake circuit of the generator control system in Embodiment 1. FIG. 2 is a time chart showing an operation example of the hydroelectric power generation system according to the first embodiment. 3 is a graph showing speed-output characteristics of the prime mover in the first embodiment. 2 is a time chart illustrating an operation example of the hydroelectric power generation system according to the first embodiment. 3 is a graph showing speed-output characteristics of the prime mover in the first embodiment. 2 is a time chart illustrating an operation example of the hydroelectric power generation system according to the first embodiment. 3 is a graph showing speed-output characteristics of the prime mover in the first embodiment. The block diagram which shows the hydroelectric power generation system in Embodiment 2. FIG. The block diagram which shows the process regarding the dynamic brake circuit of the generator control in Embodiment 2. FIG. 4 is a time chart showing an operation example of a hydroelectric power generation system according to Embodiment 2. 4 is a graph showing speed-output characteristics of a prime mover in Embodiment 2. The block diagram which shows an example of the conventional hydroelectric power generation system. The graph which shows the speed-output characteristic of the motor | power_engine in the past.

  Hereinafter, Embodiments 1 and 2 of the hydroelectric power generation system according to the present invention will be described in detail with reference to FIGS.

[Embodiment 1]
The configuration of the hydroelectric power generation system according to Embodiment 1 is shown in FIG. FIG. 2 shows a configuration related to the operation of the dynamic brake circuit 27 of the generator control system 25. In FIG. 2, processing related to a control command that is an output of the generator control system 25 is omitted.

  Based on FIG. 1, the structure of the hydroelectric power generation system regarding the self-sustained operation will be described. Note that the configuration of the hydroelectric power generation system related to grid connection is omitted.

The hydroelectric power generation system according to the first embodiment is for a generator (water turbine) 21 that is rotated by a water flow, a generator 22 that is connected to the prime mover 21 by a shaft, and a generator control that converts output power of the generator 22 into DC power. Power conversion circuit 23 and power conversion for output voltage control that converts the power converted into direct current into power that is a constant voltage (equivalent to the voltage of system 20 at normal time) for supplying power to a self-sustained operation load (not shown) And a circuit 24.
Since the prime mover (water turbine) 21 and the generator 22 are connected by a shaft, the rotational speed of the prime mover (water turbine) 21 and the rotational speed of the generator 22 are equal.

  In addition, the hydraulic power generation system according to the first embodiment gives a control command for making the DC voltage constant to the power conversion circuit 23 for controlling the generator, and also gives a dynamic brake operation command / stop command to the dynamic brake control system 28. The control system 25, the grid interconnection control system 26 that gives an output voltage control command to the power conversion circuit 24 for output voltage control, the direct current that connects the power conversion circuit 23 for generator control and the power conversion circuit 24 for output voltage control Based on a dynamic brake circuit 27 having a series connection of a dynamic brake resistor 27a and a dynamic brake element 27b connected between PN of the voltage unit, and a dynamic brake operation command / stop command output by the generator control system 25 A control command is output to the dynamic brake circuit 27 It includes a dynamic brake control system 28, a.

  The hydroelectric power generation system according to the first embodiment inputs speed detection estimation means 29a for detecting or estimating the rotational speed of the prime mover 21 or the generator 22 and a speed setting range as a mechanical resonance point to the generator control system 25. Speed range setting input means 30a, determination time input means 31 for inputting continuous operation determination time for determining that continuous operation is performed at the mechanical resonance point to the generator control system 25, and speed to the generator control system 25 And a stop determination time input means 32 for inputting a stop determination time for determining that the set range has been removed.

  The generator control system 25 includes a speed comparison unit 33 that compares the rotational speed of the prime mover 21 or the generator 22 output from the speed detection estimation unit 29a with a speed setting range as a mechanical resonance point, and a speed comparison unit 33 that uses the prime mover. The first time measuring means 34 that measures time when the rotational speed of the generator 21 or the generator 22 is within the speed setting range that is the mechanical resonance point, and the time measured by the first time measuring means 34 is the continuous operation determination time. First time comparing means 35 for outputting an operation command to the dynamic brake control system 28 when it has elapsed.

  Further, the generator control system 25 is configured so that when the first time comparison means 35 gives an operation command to the dynamic brake control system 28, the speed comparison means 33 is out of the speed setting range where the rotational speed of the generator is the mechanical resonance point. The second time measuring means 36 for measuring the time and the second instruction for outputting a stop command to the dynamic brake control system 28 when the time measured by the second time measuring means 36 has passed the stop determination time. Time comparison means 37. Although not shown in FIG. 1, as in FIG. 13, a self-sustained operation load (15 in FIG. 13) and a system-side switch (FIG. 13) between the power conversion circuit 24 for output voltage control and the system 20. 12) is connected.

  As described above, the hydraulic power generation system according to the first embodiment suppresses continuous operation at the mechanical resonance point of the generator 22 during self-sustained operation.

  In the hydroelectric power generation system according to the first embodiment, the speed setting range in which the rotational speed of the prime mover 21 or the generator 22 detected or estimated by the speed detection estimating means 29a becomes the predetermined mechanical resonance point set by the speed range setting input means 30. Is measured by the first time measuring means 34, and when the measured time has passed the continuous operation determination time, the dynamic brake circuit 27 is operated to rotate the motor 21 or the generator 22. The speed is moved out of the mechanical resonance point speed range.

  FIG. 3 shows an operation example of the hydraulic power generation system according to the first embodiment, and FIG. 4 shows the speed-output characteristics of the prime mover (water turbine) 21. FIG. 4 is a characteristic curve when the flow rate (water volume) of the water flow received by the prime mover (turbine) 21 is constant. The speeds 1 to 3 in FIGS. 3 and 4 correspond to each other.

Based on FIG. 3, FIG. 4, operation | movement of the hydroelectric power generation system in this Embodiment 1 is demonstrated.
(1) The hydropower generation system is operating independently at a speed 1 until time t1. Assume that the power supplied to the self-sustaining operation load is equal to the output 1 of the prime mover (turbine) 21 shown in FIG. Therefore, the prime mover (water turbine) 21 is operating at a constant speed 1. Here, for the sake of simplicity, the losses of the generator 22, the power conversion circuit 23 for controlling the generator, and the power conversion circuit 24 for controlling the output voltage are ignored, and the output energy of the prime mover (water turbine) 21 = the output energy of the generator 22. = Output energy of the power conversion circuit 24 for controlling the output voltage (power supply energy to the self-sustained operation load).
(2) At time t1, the autonomous driving load decreases. Furthermore, since the power conversion circuit 24 for controlling the output voltage performs control to make the output voltage (voltage of the autonomous driving load) constant, the energy supplied to the autonomous driving load decreases to the output 2 in FIG. .
(3) As the energy supplied to the self-sustained operation load decreases, the output of the prime mover (turbine) 21 also decreases, and the rotational speed of the prime mover (turbine) 21 increases toward the speed 2 as shown in FIG.
(4) At time t2, the rotational speed of the prime mover (turbine) 21 enters the speed setting range. The speed comparison means 33 compares the rotational speed of the prime mover (turbine) 21 with the set speed range, and the first time measurement means 34 measures the operating time within the speed set range. In addition, after time t2, the rotational speed of the prime mover (water turbine) 21 increases to a speed of 2, and then operates at a constant speed.
(5) When the measurement time has passed the continuous operation determination time at time t3, the first time comparison means 35 determines that continuous operation at the mechanical resonance point has occurred, and the dynamic brake element 27b of the dynamic brake circuit 27 To turn on. As a result, the dynamic brake resistor 27a is connected to the PN terminal, and the load on the power control circuit 23 for controlling the generator increases rapidly. Further, since the power conversion circuit 23 for controlling the generator performs control so that the voltage of the DC voltage (voltage between the PN terminals) is constant, the current of the generator 22 is increased (that is, the generator 22 is increased). Control operation) is performed. Accordingly, the output of the prime mover (water turbine) 21 also increases, and the rotational speed of the prime mover 21 decreases toward the speed 3 according to FIG.
(6) At time t4, the speed of the prime mover 21 is out of the speed setting range. The second time measuring means 36 measures the operation time outside the speed setting range.
(7) When the operation time outside the measured speed setting range has passed the stop determination time at time t5, the second time comparison unit 37 determines that the speed setting range has been exceeded, and the dynamic brake circuit 27 The brake element 27b is turned off. This eliminates the load on the dynamic brake circuit 27 in the power conversion circuit 23 for controlling the generator, so that the power conversion circuit 23 for controlling the generator decreases the current of the generator 22 (that is, the output of the generator 22 is reduced). Control action (such as decreasing). Thereby, according to FIG. 4, the rotational speed of the motor | power_engine 21 increases toward the speed 2 balanced with a self-supporting driving | operation load.

  In the hydroelectric power generation system according to the first embodiment, the power supply to the self-sustaining operation load can be continued even while the dynamic brake circuit 27 is operating.

  Note that it is difficult to estimate the mechanical resonance point because mechanical elements such as the prime mover (water turbine) 21 and the shaft are affected. Here, as an example of a method for obtaining the speed setting range to be set (speed near the mechanical resonance point), a method in which a test combining the prime mover (water turbine) 21 and the generator 22 is performed and the rotational speed at which mechanical resonance actually occurs is obtained. There is. In this method, the continuous operation determination time at the mechanical resonance point is determined by performing a test combining the prime mover (water turbine) 21 and the generator 22 and measuring a time when there is no problem even if continuous operation at the mechanical resonance point occurs. Set a time that is less than the time and that matches the usage environment.

  Further, by changing the ratio between the stop determination time and the continuous operation determination time at the machine resonance point, the ratio between the operation time within the speed setting range and the operation time outside the speed near the machine resonance point can be adjusted.

Next, FIG. 5 illustrates the operation of the hydroelectric power generation system when the fluctuation of the self-sustained operation load exceeding the speed setting range occurs and the operation time within the speed setting range does not reach the continuous operation determination time. Moreover, the speed-output characteristic curve of the prime mover (water turbine) 21 is shown in FIG. FIG. 6 is a characteristic curve when the flow rate (water volume) of the water flow received by the prime mover (turbine) 21 is constant.
(1) The hydropower generation system is operating independently at a speed 1 until time t1. Assume that the power supplied to the self-sustaining operation load is equal to the output 1 of the prime mover (turbine) 21 in FIG. Therefore, the generator 22 is operating at a constant speed 1. Here, for the sake of simplicity, the losses of the generator 22, the power conversion circuit 23 for controlling the generator, and the power conversion circuit 24 for controlling the output voltage are ignored, and the output energy of the motor (turbine) 21 = the power conversion for controlling the output voltage. It is assumed that the output energy of the circuit 24 (power supply energy to the self-sustaining operation load).
(2) At time t1, the autonomous driving load decreases. Furthermore, since the power conversion circuit 24 for controlling the output voltage performs control to make the output voltage (the voltage of the autonomous driving load) constant, the energy supplied to the autonomous driving load decreases to the output 2 in FIG. .
(3) The output of the prime mover (turbine) 21 decreases as the energy supplied to the self-sustained operation load decreases, and the rotational speed of the prime mover (turbine) 21 increases toward the speed 2 according to FIG.
(4) At time t2, the rotational speed of the prime mover (turbine) 21 enters the speed setting range. The first time measuring means 34 measures the operating time within the speed setting range.
(5) At time t3, the measurement time measured by the first time measurement unit 34 does not exceed the continuous operation determination time and leaves the speed setting range.
(6) The rotational speed of the prime mover (turbine) 21 reaches speed 2 at time t4. Since the electric power supplied to the self-sustained operation load is equal to the output 2 of the prime mover (turbine) 21 shown in FIG. 6, the rotational speed of the prime mover 21 is constant at a speed of 2.

  As described above, according to the hydroelectric power generation system in the first embodiment, even if the fluctuation of the autonomous driving load exceeding the speed setting range occurs by setting the continuous operation determination time, it is not necessary by the dynamic brake circuit 27. It is possible to operate at a speed that balances the self-sustained operation load without generating a deceleration operation.

  The continuous operation determination time is set according to the mechanical time constant of the prime mover (water turbine) 21 and the generator 22, the amount of water flowing to the prime mover (water turbine) 21, and the fluctuation pattern of the connected autonomous operation load.

Next, FIG. 7 shows the operation when the autonomous driving load increases when the prime mover (turbine) 21 is operating at a rotational speed equal to or higher than the speed setting range and the continuous operation determination time is exceeded within the speed setting range. . Moreover, the speed-output characteristic curve of the prime mover (water turbine) 21 is shown in FIG. FIG. 8 is a characteristic curve when the flow rate (water volume) of the water flow received by the prime mover (turbine) 21 is constant.
(1) The hydropower generation system is operating independently at a speed 1 until time t1. Assume that the power supplied to the self-sustained operation load is equal to the output 1 of the prime mover (turbine) 21 shown in FIG. Therefore, the prime mover (water turbine) 21 is operating at a constant speed 1. Here, for the sake of simplicity, the losses of the generator 22, the power conversion circuit 23 for controlling the generator, and the power conversion circuit 24 for controlling the output voltage are ignored, and the output energy of the prime mover (water turbine) 21 = the power conversion for controlling the output voltage. It is assumed that the output energy of the circuit 24 (power supply energy to the self-sustaining operation load).
(2) Since the self-sustained operation load increases at time t1 and the power conversion circuit 24 for controlling the output voltage controls the output voltage (the voltage of the self-sustained operation load) to be constant, power is supplied to the self-sustained operation load. The energy increases to output 2 shown in FIG.
(3) The output of the prime mover (turbine) 21 increases as the energy supplied to the self-sustained operation load increases, and the rotational speed of the prime mover (turbine) 21 decreases toward the speed 2 according to FIG.
(4) The speed of the prime mover (turbine) 21 enters the speed setting range at time t2. The first time measuring means 34 measures the operating time within the speed setting range.
(5) When the measurement time exceeds the set continuous operation determination time at time t3, the first time comparison means 35 determines that continuous operation at the mechanical resonance point has occurred and the dynamic brake circuit 27 The element 27b is turned on. As a result, the dynamic brake resistor 27a is connected to the PN terminal, and the load on the power control circuit 23 for controlling the generator increases rapidly. Further, since the power conversion circuit 23 for controlling the generator controls the DC voltage (voltage between the PN terminals) to be constant, the current of the generator 22 is increased (that is, the generator The control operation (such as increasing the output of 22) is performed. Accordingly, the output of the prime mover (turbine) 21 also increases, and the rotational speed of the prime mover (turbine) 21 decreases toward the speed 3 according to FIG.
(6) At time t4, the rotational speed of the prime mover (turbine) 21 is outside the speed setting range. The second time measuring means 36 measures the operation time outside the speed setting range.
(7) At time t5, the measurement time has passed the stop determination time, and the second time comparison means 37 determines that the rotational speed of the prime mover (turbine) 21 has deviated from the speed setting range, and the dynamic brake circuit 27 The brake element 27b is turned off. This eliminates the load on the dynamic brake circuit 27 in the power conversion circuit 23 for controlling the generator, so that the power conversion circuit 23 for controlling the generator reduces the current of the generator 22 (that is, the output of the generator 22 is reduced). Control action (such as decreasing).
(8) The rotational speed of the prime mover (turbine) 21 reaches a speed 2 that balances with the autonomous driving load. Since the power supplied to the self-sustained operation load is equal to the output 2 of the prime mover (turbine) 21 shown in FIG. 8, the rotational speed of the prime mover (turbine) 21 is constant at a speed of 2.

  The speed of change in the rotational speed of the generator 22 when the self-sustained operation load changes depends on the mechanical time constant of the prime mover (turbine) 21 and the generator 22, the amount of water flowing through the prime mover (turbine) 21, and the like. Therefore, even if the speed balanced with the self-sustained operation load is not within the speed setting range as in this operation, there is a possibility that continuous operation in the speed setting range may occur during acceleration or deceleration of the rotational speed of the prime mover (water turbine) 21. .

  According to the first embodiment, continuous operation in the speed setting range can be avoided regardless of factors such as the machine time constant and the amount of water.

[Embodiment 2]
A hydroelectric power generation system according to the second embodiment is shown in FIG. Moreover, the structure of the generator control system 25 regarding the dynamic brake circuit 27 is shown in FIG. In addition, the process regarding the control command which is an output of the generator control system 25 is not shown in FIG. Here, description of the operation of each component at the time of grid interconnection operation is omitted.

  In the first embodiment, the determination target of continuous operation at the mechanical resonance point is the rotational speed of the prime mover 21 or the generator 22. However, in the second embodiment, the determination target is changed to the output power of the generator 22. In the hydraulic power generation system according to the second embodiment, an output measurement estimation unit 29 b that measures or estimates the output power of the generator 22 is provided in the generator control system 25. In the second embodiment, the output range setting input means 30b inputs the output range of the generator 22 that is the mechanical resonance point.

  The hydroelectric power generation system according to the second embodiment includes a flow rate control means (for example, a governor) 38 for controlling the amount of water flowing to the prime mover (turbine) 21 at a constant level, and a flow rate control controller for controlling the flow rate control means 38. 39.

  Although not shown in FIG. 9, as in FIG. 1, a self-sustained operation load (15 in FIG. 13) and a system-side switch (FIG. 13) are provided between the power conversion circuit 24 for controlling the output voltage and the system 20. 12) is connected. Other configurations are the same as those of the first embodiment.

(Description of action / operation)
When the flow rate of water is constant, the speed-output characteristics of the prime mover (water turbine) 21 are constant, and the output of the generator 22 corresponding to the mechanical resonance point is also a constant value. In the second embodiment, the operation determination at the mechanical resonance point is determined not by the rotational speed of the prime mover 21 or the generator 22 but by the output value of the generator 22, and the generator 22 continuously operates within the set output range. When the dynamic brake circuit 27 is operated and the output (electric power) of the generator 22 is increased, the output range of the generator 22 corresponding to the mechanical resonance point is deviated and continuous at the mechanical resonance point. It suppresses driving.

  Even in an environment where the rotational speed of the prime mover 21 or the generator 22 cannot be detected / estimated by determining the continuous operation at the mechanical resonance point in the output power of the generator 22 instead of the rotational speed of the prime mover 21 or the generator 22, Continuous operation at the mechanical resonance point can be suppressed by the operation of the dynamic brake circuit 27. In the second embodiment, the amount of water flowing to the prime mover (turbine) 21 is controlled to a constant value by the flow controller 39 and the flow controller 38.

FIG. 11 shows an operation example of the second embodiment, and FIG. 12 shows an output-speed characteristic curve when the flow rate of water is constant.
(1) The hydropower generation system is operating independently at a speed 1 until time t1. Assume that the power supplied to the self-sustaining operation load is equal to the output 1 of the prime mover (turbine) 21 shown in FIG. Therefore, the generator 22 is operating at a constant speed 1. Here, for the sake of simplicity, the losses of the generator 22, the power conversion circuit 23 for controlling the generator, and the power conversion circuit 24 for controlling the output voltage are ignored, and the output energy of the prime mover (water turbine) 21 = the output energy of the generator 22. = Output energy of the power conversion circuit 24 for controlling the output voltage (power supply energy to the self-sustained operation load).
(2) The independent operation load decreases at time t1. Furthermore, since the power conversion circuit 24 for output voltage control performs control to make the output voltage (voltage of the autonomous driving load) constant, the energy supplied to the autonomous driving load is reduced to the output 2 shown in FIG. Go.
(3) The output of the prime mover (turbine) 21 decreases as the energy supplied to the self-sustained operation load decreases, and the rotational speed of the prime mover (turbine) 21 increases toward the speed 2 according to FIG.
(4) At time t2, the output of the motor (turbine) 21 enters the output setting range. The first time measuring means 34 measures the operation time within the set output range.
(5) During the period from time t2 to time t3, the output of the prime mover (turbine) 21 becomes output 2, which balances with the energy required for the autonomous driving load. Therefore, the output and speed of the prime mover (turbine) 21 are constant values. Furthermore, the output 2 at this time is within the output setting range (output corresponding to the speed near the mechanical resonance point).
(6) When the measurement time has passed the continuous operation determination time at time t3, the first time comparison means 35 determines that continuous operation at the mechanical resonance point has occurred, and the dynamic brake element 27b of the dynamic brake circuit 27 To turn on. As a result, the dynamic brake resistor 27a is connected to the PN terminal, and the load of the power conversion circuit 23 for controlling the generator increases rapidly, so that the current of the generator 22 is increased (that is, the output of the generator 22 is increased). Control action). Accordingly, the output of the prime mover (turbine) 21 is increased, and the rotational speed of the prime mover (turbine) 21 is decreased toward the speed 3 according to FIG.
(7) At time t4, the rotational speed of the prime mover (turbine) 21 is out of the output setting range. The second time measuring means 36 measures the operating time outside the output setting range.
(8) When the measurement time exceeds the stop determination time at time t5, the second time comparison unit 37 determines that the output setting range has been exceeded, and turns off the dynamic brake element 27b of the dynamic brake circuit 27. This eliminates the load of the dynamic brake resistor 27a in the power control circuit 23 for controlling the generator, so that a control operation that reduces the current of the generator 22 (that is, reduces the output of the generator 22) is performed. Do. Thereby, according to FIG. 12, the output of the generator 22 decreases toward the output 2 balanced with the self-sustaining operation load.

  Note that it is difficult to estimate the mechanical resonance point because mechanical elements such as the prime mover (water turbine) 21 and the shaft are affected. Here, as an example of a method for obtaining the output setting range to be set (the output of the prime mover (turbine) 21 corresponding to the speed near the mechanical resonance point), a test combining the prime mover (turbine) 21 and the generator 22 is performed, and the actual machine resonance There is a method of obtaining from the output generated.

  In the first and second embodiments, the control command (command for making the DC voltage constant) output by the generator control system 25 and the control command (command for making the output voltage constant) output by the grid interconnection control system 26 The operation does not change regardless of the rotational speed of the prime mover 21 or the generator 22 during the autonomous operation.

  Therefore, unlike in Patent Document 2, control commands to the power control circuit 23 for controlling the generator and the power conversion circuit 24 for controlling the output voltage are not changed in order to suppress the operation at the mechanical resonance point. According to the first and second embodiments, the amount of calculation processing related to the operation of the dynamic brake circuit 27 increases, but the amount of calculation processing related to the operation of the power conversion circuit 23 for generator control and the power conversion circuit 24 for output voltage control does not change. Therefore, it is not necessary to provide a higher-speed arithmetic processing device for controlling the power conversion circuit 23 for controlling the generator and the power conversion circuit 24 for controlling the output voltage.

  According to the first and second embodiments, in the variable speed hydraulic power generation system, it is possible to reduce the continuous operation time at the mechanical resonance point where the unstable operation occurs during the self-sustaining operation when the system is disconnected. .

  Thereby, the metal fatigue of the motor | power_engine (water turbine) 21 and the generator 22 in a hydroelectric power generation system is reduced, and the lifetime of a system improves.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

21 ... Motor (turbine)
DESCRIPTION OF SYMBOLS 22 ... Generator 23 ... Power conversion circuit for generator control 24 ... Power conversion circuit for output voltage control 27 ... Dynamic brake circuit 29 ... Speed detection estimation means

Claims (2)

A prime mover that is rotated by water flow,
A generator connected to the prime mover;
A power conversion circuit for controlling the generator that converts the output power of the generator into DC power;
A power conversion circuit for output voltage control that converts the power converted into direct current into power for supplying power to a self-supporting load;
A switch that disconnects the system from the power conversion circuit for output voltage control;
A dynamic brake circuit connected to a DC voltage section between a power conversion circuit for generator control and a power conversion circuit for output voltage control, and having a series connection of a dynamic brake element and a dynamic brake resistor;
Speed detection and estimation means for detecting or estimating the rotational speed of the prime mover or generator;
When the switch is opened and the system is disconnected from the power conversion circuit for output voltage control, the power output from the generator to the self-supporting load connected to the output of the power conversion circuit for output voltage control is provided. A hydroelectric power generation system that supplies power,
Based on the mechanical resonance point of the hydroelectric power generation system, set a predetermined speed setting range of the prime mover or generator,
During self-sustained operation, if the motor or generator rotation speed is continuously within the predetermined speed setting range for more than the continuous operation determination time, the dynamic brake element is turned on and the motor or generator is turned on. Move the rotation speed out of the predetermined speed setting range,
Hydroelectric power generation characterized in that the dynamic brake element is turned off when the time after the rotation speed of the prime mover or the generator is moved outside the predetermined speed setting range has continuously elapsed for the stop determination time or longer. system. A prime mover that is rotated by water flow,
A generator connected to the prime mover;
A power conversion circuit for controlling the generator that converts the output power of the generator into DC power;
A power conversion circuit for output voltage control that converts the power converted into direct current into power for supplying power to a self-supporting load;
A switch that disconnects the system from the power conversion circuit for output voltage control;
A dynamic brake circuit connected to a DC circuit between the power conversion circuit for generator control and the power conversion circuit for output voltage control, and having a series connection of a dynamic brake element and a dynamic brake resistor;
A flow rate adjusting means for adjusting a flow rate of a water flow input to the prime mover; a flow rate controller for controlling the flow rate adjusting means;
Output power detection and estimation means for detecting or estimating the output power of the generator;
The power is output by the generator to a self-supporting load connected to the output of the power converter for output voltage control when the switch is opened and the system is disconnected from the power converter circuit for output voltage control. A hydroelectric power generation system,
Set a predetermined output setting range based on the mechanical resonance point of the hydroelectric power generation system,
When the flow rate controller controls the flow rate of the water flow to be constant during self-sustained operation, and the time during which the output power of the generator is within the specified output setting range during the self-sustained operation exceeds the continuous operation determination time. The dynamic brake element is turned on to move the output power of the generator out of the predetermined output range,
A hydraulic power generation system, wherein a dynamic brake element is turned off when a time after the output power of a generator is moved out of a predetermined output setting range has elapsed continuously for a stop determination time or longer.

Images