Electrical power generation system

Abstract

To provide an electrical power generation system that can properly output electric power to an electrical power system.SOLUTION: An electrical power generation system 10 is provided with: a planetary gear mechanism 23 having a first shaft, a second shaft and a third shaft; a waterwheel 11, connected to the first shaft, which is rotated by flow of fluid; a first rotary electric machine 21, connected to the second shaft, which generates electric power by rotation of the second shaft; a motor 41, connected to the third shaft, which can adjust rotation speed of the third shaft; and inverters 51 and 52 that convert electric power generated by the first rotary electric machine 21 and output the electric power to an electrical power system 90. An electric power generation control device 15 comprises an obtaining part that obtains a parameter showing a rotating state of the waterwheel 11 and a rotation control part that makes the motor 41 control rotation speed of the third shaft, on the basis of the parameter obtained by the obtaining part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The disclosure in this specification relates to a power generation system that generates electricity using energy sources such as hydraulic power and wind power.

Background Art

[0002] Conventionally, various power generation systems that generate electricity using renewable energy such as hydraulic power and wind power have been proposed. For example, in the wind power generation device described in Patent Document 1, it has a windmill having a rotor, a main generator and a motor-cum-auxiliary generator connected to the main shaft of the rotor, and controls the motor-cum-auxiliary generator according to the wind speed detected by the wind speed detection means. And by controlling the motor-cum-auxiliary generator, the power generation efficiency under low wind speeds is increased, and power generation is efficiently performed even during strong winds.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the technology described in Patent Document 1 above, since the windmill and the main generator rotate at the same rotational speed or rotation ratio, the upper limit of the rotational speed of the windmill is limited by the generated voltage of the main generator. Therefore, there is a concern that the versatility will be reduced. In addition, in a power generation system that supplies generated power to a power grid, continuous power supply in a stable state is required, and there is room for improvement.

[0005] This disclosure has been made in view of the above circumstances, and an object thereof is to provide a power generation system that can appropriately output power to a power grid.

Means for Solving the Problems

[0006] The power generation system of the present disclosure includes a planetary gear mechanism having a first shaft, a second shaft, and a third shaft, a rotating body connected to the first shaft and rotated by the flow of a fluid, a generator connected to the second shaft and generating electricity by the rotation of the second shaft, a rotation adjustment device connected to the third shaft and capable of adjusting the rotational speed of the third shaft, a power conversion device that power-converts the generated power of the generator and outputs it to a power grid, an acquisition unit that acquires a parameter indicating the rotational state of the rotating body, a rotation control unit that controls the rotational speed of the third shaft by the rotation adjustment device based on the parameter acquired by the acquisition unit, and is provided with.

[0007] In the power generation system having the above configuration, a rotating body rotated by the flow of a fluid, a generator, and a rotation adjustment device are respectively connected to the three shafts (the first shaft, the second shaft, and the third shaft) of the planetary gear mechanism, and the rotation of the rotating body can be transmitted to the generator via the planetary gear mechanism to cause the generator to generate electricity. Further, by power-converting the generated power of the generator with the power conversion device, it is possible to output a system voltage to the power grid.

[0008] In a planetary gear mechanism, the rotational speed of the remaining one shaft is determined by the rotational speeds of two shafts. Therefore, when the first shaft of the planetary gear mechanism rotates due to the rotation of a rotating body accompanying the flow of a fluid, the rotational speed of a generator connected to the second shaft can be increased or decreased by the rotational speed of a rotation adjustment device connected to the third shaft. In particular, in this case, a parameter indicating the rotational state of the rotating body is acquired, and based on this parameter, the rotational speed of the third shaft is controlled by the rotation adjustment device. Thereby, for example, when the flow velocity of a fluid composed of water, air, or the like excessively decreases or increases, the rotational speed of the third shaft is controlled according to the decrease or increase in the flow velocity, so that the rotational speed of the generator can be controlled to an appropriate value. That is, even if the rotational state of the rotating body changes according to the usage conditions, the rotational speed of the generator can be appropriately adjusted, and the versatility with respect to the usage conditions can be enhanced. As a result, power can be appropriately output to the power grid.

Brief Description of the Drawings

[0009]

Figure 1

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Mode for Carrying Out the Invention

[0010] Hereinafter, an embodiment in which the power generation system according to the present disclosure is embodied will be described with reference to the drawings. The power generation system 10 of the present embodiment is a hydroelectric power generation system constructed using a transaxle removed from an end-of-life hybrid vehicle and a power control unit (PCU: Power Control Unit). It generates electricity using hydro energy, which is renewable energy, and outputs the generated electric power as grid power.

[0011] The configuration of the power generation system 10 will be described with reference to FIG. 1. The power generation system 10 includes a waterwheel 11 as a rotating body rotated by water, a transaxle 13 and a PCU 14 removed from a hybrid vehicle, and a power generation control device 15, and AC power is output from the PCU 14 to the power grid 90. The power generation system 10 has a configuration in which, for example, water flowing from a water storage tank or a reservoir is used as an energy source, and the waterwheel 11 is provided in a water channel extending from the water storage tank or the like. Due to the water flow in the water channel, the waterwheel 11 and the rotating shaft 12 fixed to the waterwheel 11 rotate.

[0012] The transaxle 13 has a first rotating electric machine 21 (MG1), a second rotating electric machine 22 (MG2), a planetary gear mechanism 23, and a differential gear 24. The planetary gear mechanism 23 and the second rotating electric machine 22 are connected via a drive shaft 25, and the differential gear 24 is connected to the drive shaft 25 via a gear portion 26. The differential gear 24 has a pair of side gears 24a and 24b, and shaft portions 27a and 27b are connected to the side gears 24a and 24b, respectively.

[0013] The first rotating electrical machine 21 and the second rotating electrical machine 22 are three-phase AC motors composed of, for example, a permanent magnet motor or a field winding type motor. In this power generation system 10, the first rotating electrical machine 21 functions as a generator that generates electricity as the waterwheel 11 rotates.

[0014] FIG. 2 is a skeleton diagram showing a configuration example of the transfer axle 13. The planetary gear mechanism 23 includes a sun gear 31, a ring gear 32 that rotates coaxially with the sun gear 31, a plurality of pinion gears 33 that mesh with both the sun gear 31 and the ring gear 32, and a planetary carrier 34 that rotates coaxially with the sun gear 31 as the pinion gears 33 rotate. In the planetary gear mechanism 23, the waterwheel 11 is connected to the planetary carrier 34 via a rotating shaft 12. The first rotating electrical machine 21 is connected to the sun gear 31. The second rotating electrical machine 22 and the differential gear 24 are connected to the ring gear 32 via a drive shaft 25 and a gear unit 26. In the planetary gear mechanism 23, the sun gear 31, the ring gear 32, and the planetary carrier 34 correspond to the three axes of the first axis, the second axis, and the third axis.

[0015] As a configuration example of the gear unit 26, a counter driven gear 35 is integrally provided on the ring gear 32. The counter driven gear 35 is connected to the second rotating electrical machine 22 via a reduction gear 36. Further, the counter driven gear 35 is connected to the differential gear 24 via a reduction gear 37.

[0016] The transaxle 13 also has a parking lock mechanism 38 (P / L). The parking lock mechanism 38 includes, for example, an actuator, a parking lock gear, and a parking ball (not shown). When the parking ball as an engaging member engages with the parking lock gear by driving the actuator, the parking lock state (operating state) is achieved. In the parking lock state, the rotation of the ring gear 32 meshing with the parking lock gear is restricted. Note that the parking lock mechanism may mesh the parking lock gear with the counter driven gear 35 to restrict the rotation of the counter driven gear 35. In any case, the parking lock mechanism 38 may be such that it switches between a state allowing the rotation of the ring gear 32 of the planetary gear mechanism 23 and a state prohibiting the rotation, that is, it may be capable of restricting the rotation of the ring gear 32.

[0017] As shown in FIG. 3, in the state where the transaxle 13 is mounted in the hybrid vehicle 100, the engine 101 as an internal combustion engine is connected to the planetary carrier 34 of the planetary gear mechanism 23, the first rotating electric machine 21 is connected to the sun gear 31, and the second rotating electric machine 22 is connected to the ring gear 32. In the hybrid vehicle 100, power generation is performed in the first rotating electric machine 21 as the engine 101 rotates. Further, the shaft portions 27a and 27b on both sides of the differential gear 24 are connected to the left and right wheels 102. In the hybrid vehicle 100, running is possible by driving the wheels by the second rotating electric machine 22.

[0018] Returning to the description of FIG. 1, among the shaft portions 27a and 27b fixed to the pair of side gears 24a and 24b in the differential gear 24, a motor 41 is connected to one shaft portion 27a (one side gear 24a), and a brake device 42 is connected to the other shaft portion 27b (the other side gear 24b). The motor 41 is rotatable in both forward and reverse directions and functions as a rotation adjustment device for adjusting the rotational speed of the ring gear 32. The brake device 42 is, for example, an electromagnetic brake, which generates an electromagnetic force by energizing a coil and holds the shaft portion 27b on the side opposite to the motor 41 in the differential gear 24 in a rotationally stopped state.

[0019] A rotation angle sensor 28 for detecting the rotation angle of the rotation shaft is provided on the rotation shaft (rotor rotation shaft) of the first rotating electrical machine 21. Further, the first rotating electrical machine 21 has three-phase stator coils, and a power generation voltage sensor 29 for detecting the generated voltage of the first rotating electrical machine 21 is provided on the power line connected to the stator coils. Detection signals of these sensors 28 and 29 are sequentially input to the power generation control device 15.

[0020] The PCU 14 includes a first inverter 51, a second inverter 52, a DC-DC converter 53, and an MG control device 54. The first inverter 51 and the second inverter 52 are three-phase inverters. The first inverter 51 and the second inverter 52 each have an upper arm switch 61 and a lower arm switch 62 for each phase, and orthogonal power conversion is performed by switching the switches 61 and 62 of the upper and lower arms in each phase at a predetermined cycle.

[0021] The first inverter 51 and the second inverter 52 are provided with their respective high-potential side and low-potential side DC terminals connected. That is, in each of these inverters 51 and 52, the high-potential path 63, which is the electrical path on the high-potential side, and the low-potential path 64, which is the electrical path on the low-potential side, are continuous with each other. A smoothing capacitor 65 and a voltage sensor 66 are connected in parallel between the high-potential path 63 and the low-potential path 64. Also, the AC terminals of the first inverter 51 are connected to the three-phase stator coils of the first rotating electrical machine 21, and the AC terminals of the second inverter 52 are connected to the power grid 90.

[0022] The first inverter 51 converts the AC voltage output from the first rotating electrical machine 21 into a DC voltage. Also, the second inverter 52 reconverts the DC voltage converted by the first inverter 51 into an AC voltage and outputs it to the power grid 90. A grid voltage sensor 71 for detecting the voltage (grid voltage) output to the power grid 90 is provided at the AC terminals of the second inverter 52.

[0023] Also, the DC-DC converter 53 has, as is well known, an upper-arm switch and a lower-arm switch, and a reactor and a capacitor connected to the midpoint between those upper and lower arms, and boosts the voltage of the battery 55 by switching the upper and lower arms. The battery 55 is a power storage device with a terminal voltage of, for example, several hundred volts, and is, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. Note that in this power generation system 10, it is also possible to omit the DC-DC converter 53 and the battery 55 in the PCU 14.

[0024] In the hybrid vehicle 100 shown in FIG. 3, the first inverter 51 is provided as a power conversion circuit for the first rotating electric machine 21, and the second inverter 52 is provided as a power conversion circuit for the second rotating electric machine 22. That is, in the hybrid vehicle 100, the PCU 14 having the two inverters 51, 52 and the DC-DC converter 53 is provided as a rotating electric machine driving component for driving the two rotating electric machines 21, 22. On the other hand, in the power generation system 10 of FIG. 1, in the PCU 14, the inverters 51, 52 and the DC-DC converter 53 are diverted with their mutual connections remaining as they are. As a difference from the hybrid vehicle 100, a power grid 90 is connected to the AC terminal of the second inverter 52 instead of the second rotating electric machine 22.

[0025] The MG control device 54 is mainly composed of a microcomputer including a processor, a memory, and the like. The MG control device 54 performs switching control for turning on and off the switches 61, 62 of the upper and lower arms for each phase in the first inverter 51 and the second inverter 52. In the present embodiment, the MG control device 54 performs switching control based on the output command and the phase command received from the power generation control device 15. The output command is a torque command or a current command of the first rotating electric machine 21, and feedback control based on the deviation between the detected current and the torque command or current command given as the d, q axis components of the permanent magnet motor may be performed. Regarding the phase command, by giving phase information based on the phase of the grid voltage as the angle information at the time of two-phase to three-phase conversion calculation used in the feedback control, the phase or frequency of the first rotating electric machine 21 may be controlled. The MG control device 54 causes the inverters 51, 52 to perform a power factor correction (PFC) operation, and converts the AC current into a DC current so as to make the power factor approach 1.0 or reduce the high-frequency components. By the grid-connected operation of this PCU 14, for example, the grid voltage is output at a frequency of 60 Hz.

[0026] The power generation control device 15 is mainly composed of a microcomputer (equivalent to a "computer"). The microcomputer includes a processor and a memory (storage unit). The microcomputer provides various functions as shown in FIG. 6, for example. The functions provided by the microcomputer can be provided by software recorded in a physical memory device and a computer that executes it, software only, hardware only, or a combination thereof. For example, when the microcomputer is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a number of logic circuits or an analog circuit. For example, the microcomputer executes a program stored in a non-transitory tangible storage medium as its own storage unit. The program includes, for example, the programs of the processes shown in FIG. 7 and the like. When the program is executed, the method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. Note that the program stored in the storage unit can be updated via a network such as the Internet, for example.

[0027] FIG. 4 shows an example of a collinear diagram of the planetary gear mechanism 23. In FIG. 4, the rotation speed of the sun gear 31, that is, the rotation speed of the first rotating electric machine 21, is shown on the S axis, the rotation speed of the planetary carrier 34, that is, the rotation speed of the water turbine 11, is shown on the C axis, and the rotation speed of the ring gear 32 is shown on the R axis. In the collinear diagram, the rotation speeds of the three axes of the planetary gear mechanism 23 are represented linearly. In the power generation system 10, in the basic state, the rotation speed of the ring gear 32 is fixed at zero, and in this state, the planetary carrier 34 rotates as the water turbine 11 rotates due to the water flow. Then, the sun gear 31 (the first rotating electric machine 21) rotates at a rotation speed according to the relationship of the reduction ratios of the three axes of the planetary gear mechanism 23. Power generation is performed by the rotation of the first rotating electric machine 21.

[0028] Incidentally, in the power generation system 10, for example, when the rotational speed of the water turbine 11 varies in response to a change in the flow velocity of the water flow in the water channel, the rotational speed of the first rotating electrical machine 21 varies with the rotational variation of the water turbine 11, and consequently, the generated voltage of the first rotating electrical machine 21 varies. When the generated voltage of the first rotating electrical machine 21 changes excessively, the grid connection cannot be continued. That is, as shown by the dashed-dotted line in FIG. 4, for example, when the rotational speed (carrier rotational speed) of the water turbine 11 rises from N1 to N2, the rotational speed (sun gear rotational speed) of the first rotating electrical machine 21 rises with this rotational increase and goes outside the allowable range X. As a result, the generated voltage of the first rotating electrical machine 21 rises excessively, and the grid connection cannot be continued. Although not shown, when the rotational speed (carrier rotational speed) of the water turbine 11 decreases, it is conceivable that the rotational speed (sun gear rotational speed) of the first rotating electrical machine 21 decreases with this rotational decrease and goes outside the allowable range X. Note that the allowable range X may be determined by the target rotational speed of the first rotating electrical machine 21 when performing grid connection operation.

[0029] Therefore, in the present embodiment, in the planetary gear mechanism 23, when rotational variations occur in two axes, namely the sun gear 31 and the planetary carrier 34, with a change in the flow velocity of the water flow, by controlling the rotational speed of the ring gear 32, which is the remaining one axis, an excessive change in the rotational speed of the first rotating electrical machine 21, that is, an excessive change in the generated voltage, is suppressed.

[0030] In the present embodiment, the rotational speed of the ring gear 32 of the planetary gear mechanism 23 can be adjusted by a motor 41 as a rotation adjustment device. More specifically, one of the pair of shaft portions 27a, 27b connected to the differential gear 24 is set in a brake-on state (that is, a state where the rotation of the shaft portion 27b is stopped), and in this state, the motor 41 is driven on the positive rotation side or the negative rotation side. Thereby, the rotational speed of the ring gear 32 of the planetary gear mechanism 23 is adjusted as a rotational speed on the positive side or the negative side, and consequently, the rotational speed of the first rotating electrical machine 21 connected to the sun gear 31, that is, the rotational speed of the generator, is adjusted to increase or decrease.

[0031] When the rotation speed of the ring gear 32 is adjusted by the motor 41, the changes in the rotation speeds of the three shafts of the planetary gear mechanism 23 will be described with reference to FIGS. 5(a) and 5(b).

[0032] In FIG. 5(a), similar to FIG. 4, it is assumed that the rotation speed of the waterwheel 11 (carrier rotation speed) rises from N1 to N2. In such a case, the motor 41 is rotationally driven in the positive direction, causing the rotation speed of the ring gear 32 to increase in the positive direction. As a result, the excessive increase in the rotation speed of the first rotating electrical machine 21 (sun gear rotation speed) is suppressed and maintained within the allowable range X.

[0033] Also, in FIG. 5(b), it is assumed that the rotation speed of the waterwheel 11 (carrier rotation speed) drops from N1 to N3. In such a case, the motor 41 is rotationally driven in the negative direction, causing the rotation speed of the ring gear 32 to increase in the negative direction. As a result, the excessive decrease in the rotation speed of the first rotating electrical machine 21 (sun gear rotation speed) is suppressed and maintained within the allowable range X.

[0034] FIG. 6 is a functional block diagram showing each function realized by the power generation control device 15. In FIG. 6, the acquisition unit 81 acquires parameters indicating the rotation state of the waterwheel 11. Here, the parameters indicating the rotation state of the waterwheel 11 may be those having a correlation with the rotation state of the waterwheel 11, for example, the flow velocity of the water flowing through the water channel, the amount of water per unit time, the water pressure, the rotation speed of the waterwheel 11, etc. In the present embodiment, a flow velocity sensor 72 for detecting the flow velocity V of the water is provided in the water channel where the waterwheel 11 is provided, and this flow velocity sensor 72 corresponds to the means for parameter detection. The means for parameter detection may be one that directly or indirectly detects the rotation of the waterwheel 11.

[0035] The first determination unit 82 determines whether the parameter (flow velocity V) acquired by the acquisition unit 81 is within the first range Y1. Also, the second determination unit 83 determines whether the parameter (flow velocity V) acquired by the acquisition unit 81 is within a second range Y2 that is defined within the first range Y1 and narrower than the first range Y1.

[0036] The first range Y1 and the second range Y2 are indicators for determining the flow velocity V of the water flow. Depending on whether the flow velocity V falls into any of the multiple flow velocity regions defined by the first range Y1 and the second range Y2, the processes related to the parking lock mechanism 38, the motor 41, and the brake device 42 are selectively performed. As shown in FIG. 8, the first range Y1 is a range (TH11~TH12) with the upper limit being the threshold value TH11 and the lower limit being the threshold value TH12. The second range Y2 is a range defined within the first range Y1 and narrower than the first range Y1, and is a range (TH21~TH22) with the upper limit being the threshold value TH21 and the lower limit being the threshold value TH22.

[0037] When the lock control unit 84 determines that the parameter is within the second range Y2 by the second determination unit 83, the parking lock mechanism 38 (P / L) is set to a state where the rotation of the ring gear 32 is prohibited. When it is determined that the parameter is outside the second range Y2, the parking lock mechanism 38 is set to a state where the rotation of the ring gear 32 is permitted.

[0038] When the rotation control unit 85 determines that the parameter is outside the second range Y2 by the second determination unit 83 and determines that the parameter is within the first range Y1 by the first determination unit 82, the brake device 42 is set to the brake-on state and the motor 41 is set to the rotation stop state. When it is determined that the parameter is outside the first range Y1, the brake device 42 is set to the brake-on state, and the rotation speed of the motor 41 is controlled to the positive side or the negative side based on the parameter acquired by the acquisition unit 81.

[0039] FIG. 7 is a flowchart showing the processing procedure of power generation control in the power generation system 10. This processing is executed by the power generation control device 15 at a predetermined cycle.

[0040] In FIG. 7, in step S11, as a parameter indicating the rotation state of the waterwheel 11, the flow velocity V of the water flow is acquired. Then, in step S12, it is determined whether the flow velocity V is less than the threshold value TH21. Subsequently, in step S13, it is determined whether the flow velocity V is greater than or equal to the threshold value TH22. When both steps S12 and S13 are affirmed, that is, when the flow velocity V is within the range of the threshold values TH21 to TH22 (the second range Y2), the process proceeds to step S14, where the parking lock mechanism 38 is turned on (activated), and at the same time, the electromagnetic brake in the brake device 42 is turned off. In step S15, the motor 41 is set to the rotation stop state. As a result, the ring gear 32 in the planetary gear mechanism 23 is held in the rotation stop state.

[0041] If step S12 is negated, the process proceeds to step S16. In step S16, the parking lock mechanism 38 is turned off (deactivated), and at the same time, the electromagnetic brake in the brake device 42 is turned on.

[0042] Subsequently, in step S17, it is determined whether the flow velocity V is less than the threshold value TH11. When step S17 is affirmed, that is, when the flow velocity V is within the range of the threshold values TH11 to TH21, in step S15, the motor 41 remains in the rotation stop state. When step S17 is negated, that is, when the flow velocity V is greater than or equal to the threshold value TH11, the process proceeds to step S18, where the motor 41 is rotationally driven in the forward rotation direction. As a result, as described with reference to FIG. 5(a), the rotation speed of the ring gear 32 increases on the positive side, and an excessive increase in the rotation speed of the first rotating electric machine 21 (the sun gear rotation speed) is suppressed.

[0043] In step S18, the rotational speed of the motor 41 in the forward rotation direction may be controlled based on the flow velocity V. For example, the motor rotational speed may be controlled based on the deviation between the actual value (sensor detection value) and the target value of the flow velocity V. In this case, the greater the degree of deviation of the flow velocity V from the target value of the flow velocity V, the higher the motor rotational speed. Also, the rotational speed of the motor 41 in the forward rotation direction may be a predetermined rotational speed. In any case, by controlling the rotational speed of the motor 41, the rotational speed (ring gear rotational speed) of the first rotating electrical machine 21 is controlled within the allowable range X.

[0044] Also, when step S13 is negated, the process proceeds to step S19. In step S19, the parking lock mechanism 38 is set to the off state (non-operating state), and the electromagnetic brake in the brake device 42 is set to the on state.

[0045] Thereafter, in step S20, it is determined whether the flow velocity V is equal to or greater than the threshold value TH12. When step S20 is affirmed, that is, when the flow velocity V is in the range of the threshold values TH12 to TH22, in step S15, the motor 41 is kept in the rotation stop state. When step S20 is negated, that is, when the flow velocity V is less than the threshold value TH12, the process proceeds to step S21, and the motor 41 is rotationally driven in the reverse rotation direction. As a result, as described with reference to FIG. 5(b), the rotational speed of the ring gear 32 increases on the negative side, and an excessive increase in the rotational speed (sun gear rotational speed) of the first rotating electrical machine 21 is suppressed.

[0046] In step S21, the rotational speed of the motor 41 in the reverse rotation direction may be set based on the flow velocity V. For example, similar to step S18, the motor rotational speed may be set based on the deviation between the actual value (sensor detection value) and the target value of the flow velocity V. Also, the rotational speed of the motor 41 in the reverse rotation direction may be a predetermined rotational speed.

[0047] Note that step S11 corresponds to the "acquisition unit", steps S12 and S13 correspond to the "second determination unit", and steps S17 and S20 correspond to the "first determination unit". Also, step S14 corresponds to the "lock control unit", and steps SS15, 18, and S21 correspond to the "rotation control unit".

[0048] FIG. 8 is a time chart for more specifically explaining the power generation control process during hydroelectric power generation.

[0049] In FIG. 8, before timing t1, the flow velocity V is within the first range Y1 and also within the second range Y2. At this time, since the parking lock mechanism 38 is in the on state, the rotational speed of the ring gear 32 in the planetary gear mechanism 23 is held at zero. Both the brake device 42 and the motor 41 are held in the non-operating state.

[0050] Thereafter, for example, when the flow velocity V increases due to an increase in the water volume in the waterway or the like, the rotational speed of the first rotating electrical machine 21 increases. Then, when the flow velocity V reaches the threshold value TH21 at timing t1, that is, when the flow velocity V goes outside the second range Y2, the parking lock mechanism 38 is turned off and the electromagnetic brake in the brake device 42 is turned on. However, at this point, the flow velocity V is within the first range Y1 and the motor 41 remains rotationally stopped.

[0051] Thereafter, when the flow velocity V reaches the threshold value TH11 at timing t2, that is, when the flow velocity V goes outside the first range Y1, the motor 41 is rotationally driven in the forward rotation direction. The state where the flow velocity V is equal to or greater than the threshold value TH11 is a state where the hydraulic energy is excessive, but due to the forward rotation drive of the motor 41, the rotational speed of the ring gear 32 increases on the positive side, and an excessive increase in the rotational speed (sun gear rotational speed) of the first rotating electrical machine 21 is suppressed.

[0052] Thereafter, when the flow velocity V becomes less than the threshold value TH11 at timing t3, that is, when the flow velocity V returns within the first range Y1, the rotation of the motor 41 is stopped. Also, when the flow velocity V becomes less than the threshold value TH21 at timing t4, that is, when the flow velocity V returns within the second range Y2, the parking lock mechanism 38 is returned to the on state and the brake device 42 is returned to the off state.

[0053] Although illustration is omitted, when the flow velocity V decreases due to reasons such as a decrease in the amount of water in the water channel, when the flow velocity V reaches the threshold value TH22, the parking lock mechanism 38 is turned off and the electromagnetic brake in the brake device 42 is turned on. Also, thereafter, when the flow velocity V reaches the threshold value TH12, the motor 41 is rotationally driven in the reverse rotation direction. Thereby, in a state where the hydraulic energy is too small, the rotational speed of the ring gear 32 increases negatively due to the reverse rotational drive of the motor 41, and an excessive decrease in the rotational speed (sun gear rotational speed) of the first rotating electrical machine 21 is suppressed.

[0054] Also, the situation where the flow velocity V deviates from the second range Y2 due to fluctuations in the amount of water, etc., is considered to be a situation where the flow velocity V tends to fluctuate. Therefore, for example, even if the flow velocity V becomes less than the threshold value TH21 at timing t4 in FIG. 8, the flow velocity V may again become equal to or greater than the threshold value TH21 immediately thereafter. Thus, when the flow velocity V returns from outside the second range Y2 to within the second range Y2, the brake device 42 may be kept in the brake-on state and the parking lock mechanism 38 may be kept in the off state (non-operating state) for a period until a predetermined time TA elapses from the timing when the flow velocity V returns within the second range Y2.

[0055] Specifically, it is preferable to execute the process shown in FIG. 9 as the power generation control process. In the flowchart of FIG. 9, a part of the flowchart of FIG. 7 is changed, and steps S31 to S35 are additional processes.

[0056] In FIG. 9, when the flow velocity V is equal to or greater than the threshold value TH21 (when step S12 is negated), the parking lock mechanism 38 is turned off (non-operating state), and the electromagnetic brake in the brake device 42 is turned on, and 1 is set in the flag F (steps S16, S31). Also, when the flow velocity V is less than the threshold value TH22 (when step S13 is negated), similarly, the parking lock mechanism 38 is turned off (non-operating state), the electromagnetic brake in the brake device 42 is turned on, and 1 is set in the flag F (steps S19, S32). According to steps S31 and S32, when the flow velocity V is outside the second range Y2, 1 is set in the flag F.

[0057] Also, when the flow velocity V is within the range of the threshold values TH21 to TH22 (second range Y2) (when both steps S12 and S13 are YES), in step S33, it is determined whether the flag F is 1. In this case, if it is the timing when the flow velocity V has shifted from outside the second range Y2 to within the second range Y2, step S33 is affirmed and the process proceeds to step S34. In step S34, it is determined whether a predetermined time TA has elapsed since the timing when the flow velocity V has returned within the second range Y2. The predetermined time TA may be, for example, about several minutes or about several tens of minutes.

[0058] And if the predetermined time TA has not elapsed, the present process is terminated as it is. Also, if the predetermined time TA has elapsed, after resetting the flag F to 0 in step S35, the parking lock mechanism 38 is turned on (operating state), the electromagnetic brake in the brake device 42 is turned off, and the motor 41 is set to the rotation stop state (steps S14, S15).

[0059] FIG. 10 is a time chart for more specifically explaining the power generation control process of FIG. 9. In FIG. 10, similar to FIG. 8, the flow velocity V reaches the threshold value TH21 at timing t1, and the flow velocity V reaches the threshold value TH11 at timing t2. Also, the flow velocity V becomes less than the threshold value TH11 at timing t3, and the flow velocity V becomes less than the threshold value TH21 at timing t4. At the timing t1 when the flow velocity V rises to the threshold value TH21, 1 is set in the flag F.

[0060] Here, in FIG. 10, even if the flow velocity V returns from outside the second range Y2 to inside the second range Y2, it may immediately become outside the second range Y2 again, and there is a possibility that the rotation adjustment by the motor 41 is performed. Therefore, after the flow velocity V returns to the inside of the second range Y2, the flag F is held at 1, the parking lock mechanism 38 is off, and the electromagnetic brake of the brake device 42 is on, until a predetermined time TA elapses. Here, when it is determined that the predetermined time TA has elapsed at timing t6 after the flow velocity V becomes inside the second range Y2 at timing t5, the parking lock mechanism 38 is returned to the on state, and the brake device 42 is returned to the off state. At timing t6, the flag F is reset to 0.

[0061] Note that instead of the configuration in which 1 is set in the flag F at the timing t1 when the flow velocity V becomes outside the second range Y2, it is also possible to adopt a configuration in which 1 is set in the flag F at the timing t2 when the flow velocity V becomes outside the first range Y1.

[0062] According to the present embodiment described in detail above, the following excellent effects can be obtained.

[0063] In the power generation system 10, parameters indicating the rotational state of the waterwheel 11 are acquired, and based on these parameters, the rotational speed of the ring gear 32 of the planetary gear mechanism 23 is controlled by the motor 41. Thereby, when the flow velocity V of the flowing water excessively decreases or increases, by controlling the rotational speed of the ring gear 32 according to the decrease or increase of the flow velocity V, the rotational speed of the first rotating electrical machine 21 (generator) can be controlled to an appropriate value. That is, even if the rotational state of the waterwheel 11 changes according to the usage conditions, the rotational speed of the first rotating electrical machine 21 (generator) can be appropriately adjusted, and the versatility with respect to the usage conditions can be enhanced. As a result, power can be appropriately output to the power grid 90.

[0064] The power generation system 10 was constructed using the transaxle 13 and the PCU 14 mounted on the hybrid vehicle 100. Therefore, it is possible to contribute simultaneously to the formation of a recycling-oriented society and the spread of renewable energy.

[0065] As means for adjusting the rotational speed of the ring gear 32 of the planetary gear mechanism 23, the power generation system 10 has means for setting the rotational speed of the ring gear 32 to zero by the parking lock mechanism 38, and means for adjusting the rotational speed of the ring gear 32 based on the flow velocity V by the brake device 42 and the motor 41. In this case, the situation where the flow velocity V of the flowing water is within the second range Y2 is a situation where it is less likely that the rotational speed adjustment of the ring gear 32 of the planetary gear mechanism 23 is required. By setting the parking lock mechanism 38 to the locked state (rotation prohibited state), energy consumption can be reduced compared to the case where the electromagnetic brake is in the on state. On the other hand, the situation where the flow velocity V of the flowing water is outside the second range Y2 and within the first range Y1 is a situation where it is highly likely that the rotational speed adjustment of the ring gear 32 of the planetary gear mechanism 23 is required. By setting the brake device 42 to the brake on state and the motor 41 to the rotation stop state, when the parameter is outside the first range Y1, the rotational adjustment by the motor 41 can be performed promptly.

[0066] After it is determined that the flow velocity V of the water flow is outside the second range Y2, and then it is determined that the flow velocity V has returned within the second range Y2, in the period until a predetermined time TA has elapsed from the time when the flow velocity V has returned within the second range Y2, the brake device 42 is set in the brake-on state, and the parking lock mechanism 38 is left in the off (rotation-permitted state). With this configuration, in a situation where the flow velocity V tends to fluctuate, the rotation of the ring gear 32 of the planetary gear mechanism 23 is stopped by the brake device 42 and the motor 41, and when it becomes necessary to adjust the rotation speed of the ring gear 32 by the motor 41, it becomes possible to quickly take measures.

[0067] In the hybrid vehicle, the PCU 14 has a pair of inverters 51 and 52 whose DC terminals are connected to each other. Then, in the power generation system 10, one of the AC terminals of each of the pair of inverters 51 and 52 is connected to the first rotating electric machine 21 (generator), and the other is connected to the power grid 90. In this case, the power generation system 10 can be suitably constructed by diverting the PCU 14 from the hybrid vehicle 100 to the power generation system 10.

[0068] <Other Embodiments> The above embodiment may be modified as follows, for example.

[0069] · The power generation control process of the power generation system 10 may be realized as shown in FIG. 11. The process of FIG. 11 is executed by the power generation control device 15 at a predetermined cycle. When executing this process, in the differential gear 24, the side gear 24b on the side opposite to the motor 41 among the pair of side gears 24a and 24b is held in a rotation-stopped state. For example, it is preferable that the brake device 42 is removed and the shaft portion 27b is fixed in a rotation-stopped state. Note that the parking lock mechanism 38 is in the off state.

[0070] In FIG. 11, in step S41, as a parameter indicating the rotation state of the waterwheel 11, the flow velocity V of the water flow is acquired. In steps S42 and S43, it is determined whether the flow velocity V is within a predetermined range, that is, within the range of TH11 to TH12. If the flow velocity V is within the predetermined range, the motor 41 is set to the rotation stop state (step S44).

[0071] Also, when step S42 is negated, the process proceeds to step S45, and the motor 41 is rotationally driven in the forward rotation direction. At this time, the rotational speed of the motor 41 in the forward rotation direction may be set based on the flow velocity V. Further, when step S43 is negated, the process proceeds to step S46, and the motor 41 is rotationally driven in the reverse rotation direction. At this time, the rotational speed of the motor 41 in the reverse rotation direction may be set based on the flow velocity V.

[0072] Note that in FIG. 11, step S41 corresponds to the "acquisition unit", steps S42 and S43 correspond to the "parameter determination unit", and steps S44 to S46 correspond to the "rotation control unit".

[0073] Even in a configuration where the process of FIG. 11 is executed, based on the flow velocity V of the flowing water, the rotational speed of the ring gear 32 is controlled to the positive side or the negative side by the motor 41, and thus the rotational speed of the first rotating electrical machine 21 is appropriately controlled.

[0074] · As shown in FIG. 12, the three-phase coils 111 star-connected in the stator of the second rotating electrical machine 22 may be short-circuited with each other. For example, switches 112 may be provided on the power lines (three-phase output lines) extending from the coils of each phase, and by turning on and off the switches 112, it is possible to switch between a state where the three-phase coils 111 are short-circuited and a state where they are not short-circuited. The power generation control device 15 may turn on the switch 112, for example, when it is necessary to reduce the rotational speed of the ring gear.

[0075] In this case, when the three-phase coil 111 is short-circuited, a reaction force is generated in the second rotating electrical machine 22 in a direction that hinders rotation by an external force, and the rotation of the second rotating electrical machine 22 is hindered. That is, a braking torque is generated in the second rotating electrical machine 22. Thereby, the rotational speed of the ring gear 32 of the planetary gear mechanism 23 can be adjusted. Note that the three-phase coil 111 may be configured to be short-circuited constantly.

[0076] · In the above-described embodiment, in the planetary gear mechanism 23, the water turbine 11 is connected to the planetary carrier 34, the first rotating electrical machine 21 is connected to the sun gear 31, and the second rotating electrical machine 22 and the differential gear 24 are connected to the ring gear 32. However, it is also possible to change the connection partner of each shaft in the planetary gear mechanism 23. For example, in the planetary gear mechanism 23, the water turbine 11 may be connected to the sun gear 31, the first rotating electrical machine 21 may be connected to the planetary carrier 34, and the second rotating electrical machine 22 and the differential gear 24 may be connected to the ring gear 32.

[0077] · In the above-described embodiment, in the PCU 14, the inverter 51 is used when converting the three-phase AC voltage from the first rotating electrical machine 21 into a DC voltage. However, this may be changed to a configuration using a full-wave rectifier circuit composed of a plurality of diodes.

[0078] · In the above-described embodiment, the braking device 42 is an electromagnetic brake. However, this may be changed, and the braking device 42 may be a hydraulic brake.

[0079] · It is also possible to provide a plurality of power generation systems 10 shown in FIG. 1 and connect each of these power generation systems 10 to the power grid 90.

[0080] · The power generation system 10 may be a wind power generation system that generates electricity using wind energy as renewable energy and outputs the generated electric power to the power grid. In this case, the water turbine 11 in FIG. 1 is replaced with a windmill.

[0081] ·In the above-described embodiment, the power generation system 10 was constructed by diverting the transaxle 13 and the PCU 14 from the hybrid vehicle 100, but this may be changed. For example, only the transaxle 13 may be diverted from the hybrid vehicle 100, and the power generation system 10 may be constructed by combining a power control unit, which is a component different from that of the hybrid vehicle 100, with the transaxle 13. Alternatively, the power generation system 10 may be constructed without using diverted parts from the hybrid vehicle 100.

[0082] ·The control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and its method described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the control unit and its method described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Further, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

[0083] The technical idea extracted from the above-described embodiment is described below. [Configuration 1] A planetary gear mechanism (23) having a first shaft, a second shaft, and a third shaft; A rotating body (11) connected to the first shaft and rotated by the flow of a fluid; A generator (21) connected to the second shaft and generating electricity by the rotation of the second shaft; A rotation adjustment device (41) connected to the third shaft and capable of adjusting the rotation speed of the third shaft; A power conversion device (51, 52) that power-converts the generated power of the generator and outputs it to the power grid (90); An acquisition unit (81) that acquires parameters indicating the rotation state of the rotating body; A rotation control unit (85) that controls the rotation speed of the third axis by the rotation adjustment device based on the parameters acquired by the acquisition unit; The power generation system (10) comprising the above. [Configuration 2] A differential gear (24) connected to the third axis and having a pair of side gears (24a, 24b); A motor (41) connected to one of the pair of side gears and functioning as the rotation adjustment device; A parameter determination unit that determines whether or not the parameter acquired by the acquisition unit is within a predetermined range; Comprising, in the differential gear, the other side gear opposite to the motor among the pair of side gears is held in a rotation stop state, When the parameter determination unit determines that the parameter is within the predetermined range, the rotation control unit sets the motor to a rotation stop state, and when the parameter is determined to be outside the predetermined range, based on the parameter acquired by the acquisition unit, the rotation control unit controls the rotation speed of the motor to the positive side or the negative side. The power generation system according to Configuration 1. [Configuration 3] A lock mechanism (38) that switches between a state allowing rotation of the third axis and a state prohibiting rotation; A differential gear (24) connected to the third axis and having a pair of side gears (24a, 24b); A motor (41) connected to one of the pair of side gears and functioning as the rotation adjustment device; A brake device (42) connected to the other side gear of the pair of side gears; A first determination unit (82) that determines whether or not the parameter acquired by the acquisition unit is within a first range; A second determination unit (83) that determines whether or not the parameter acquired by the acquisition unit is within a second range that is defined within the first range and narrower than the first range; When it is determined by the second determination unit that the parameter is within the second range, the lock mechanism is set to a state where rotation of the third axis is prohibited, and when it is determined that the parameter is outside the second range, a lock control unit (84) that sets the lock mechanism to a state where rotation of the third axis is permitted; comprising The rotation control unit, when it is determined by the second determination unit that the parameter is outside the second range and it is determined by the first determination unit that the parameter is within the first range, sets the brake device to the brake-on state and stops the rotation of the motor, and when it is determined that the parameter is outside the first range, sets the brake device to the brake-on state and controls the rotation speed of the motor to be positive or negative based on the parameter acquired by the acquisition unit, the power generation system according to Configuration 1. [Configuration 4] When it is determined that the parameter has returned within the second range after the parameter has gone outside the second range, during a period until a predetermined time has elapsed from the timing when the parameter has returned within the second range, the brake device is set to the brake-on state and the lock mechanism remains in the state where rotation of the third axis is permitted, the power generation system according to Configuration 3. [Configuration 5] The planetary gear mechanism includes a sun gear (31), a ring gear (32) that rotates coaxially with the sun gear, a plurality of pinion gears (33) that mesh with both the sun gear and the ring gear, and a planetary carrier (34) that rotates coaxially with the sun gear as the pinion gears rotate. The sun gear is connected to the generator as the second axis, the ring gear is connected to the rotation adjustment device as the third axis, and the planetary carrier is connected to the rotating body as the first axis. The rotation control unit controls the rotation speed of the ring gear by the rotation adjustment device based on the parameter acquired by the acquisition unit, the power generation system according to any one of Configurations 1 to 4. [Configuration 6] The power conversion device includes a first inverter (51) and a second inverter (52) that perform orthogonal power conversion, The first inverter and the second inverter have their DC terminals on the high potential side and the low potential side connected to each other, The AC terminals of the first inverter are connected to the phase current terminals of each phase in the generator, while the AC terminals of the second inverter are connected to the power grid. The power generation system according to any one of Configurations 1 to 5. [Configuration 7] The planetary gear mechanism, the generator connected to the second shaft of the planetary gear mechanism, and the differential gear (24) connected to the third shaft of the planetary gear mechanism via a drive shaft (25) are in-vehicle components mounted as a transaxle (13) in a hybrid vehicle, In the transaxle, the rotating body is connected to the first shaft of the planetary gear mechanism in place of the engine of the hybrid vehicle, The power conversion device has inverters (51, 52) that adjust the power input and output to and from the in-vehicle rotating electrical machines including the generator in the hybrid vehicle. The power generation system according to any one of Configurations 1 to 6.

Explanation of Reference Numerals

[0084] 10…Power generation system, 11…Water turbine, 21…First rotating electrical machine, 23…Planetary gear mechanism, 41…Motor, 51, 52…Inverters, 81…Acquisition unit, 85…Rotation control unit, 90…Power grid.

Claims

1. A planetary gear mechanism (23) having a first shaft, a second shaft and a third shaft, A rotating body (11) connected to the first shaft and rotating due to the flow of fluid, A generator (21) connected to the second shaft, which generates electricity by the rotation of the second shaft, A locking mechanism (38) that switches between a state that allows rotation of the third axis and a state that prohibits rotation, A differential gear (24) connected to the third shaft and having a pair of side gears (24a, 24b), A motor (41) connected to one of the pair of side gears, which can adjust the rotational speed of the third shaft, A brake device (42) connected to the other side gear of the pair of side gears, A power converter (51, 52) converts the power generated by the aforementioned generator into power and outputs it to the power grid (90), An acquisition unit (81) acquires parameters indicating the rotation state of the rotating body, A first determination unit (82) determines whether the parameter acquired by the acquisition unit is within a first range, A second determination unit (83) determines whether the parameter acquired by the acquisition unit is within the first range and within a second range that is narrower than the first range, A lock control unit (84) that, when the second determination unit determines that the parameter is within the second range, sets the lock mechanism to a state where rotation of the third axis is prohibited, and when the parameter is determined to be outside the second range, sets the lock mechanism to a state where rotation of the third axis is permitted, A rotation control unit (85) controls the rotation speed of the third shaft by the motor based on the parameters acquired by the acquisition unit, Equipped with, The rotation control unit, when the second determination unit determines that the parameter is outside the second range and the first determination unit determines that the parameter is within the first range, sets the brake device to a brake-on state and the motor to a rotation-stop state; when the parameter is determined to be outside the first range, sets the brake device to a brake-on state and controls the rotation speed of the motor to a positive or negative side based on the parameter acquired by the acquisition unit, is a power generation system (10).

2. The power generation system according to claim 1, wherein, after the parameter has fallen outside the second range, if it is determined that the parameter has returned to the second range, the brake device remains in the brake-on state and the locking mechanism remains in the rotation-permitted state of the third shaft for a predetermined period of time from the time the parameter returned to the second range until a predetermined time has elapsed.

3. The planetary gear mechanism includes a sun gear (31), a ring gear (32) that rotates coaxially with the sun gear, a plurality of pinion gears (33) that mesh with both the sun gear and the ring gear, and a planetary carrier (34) that rotates coaxially with the sun gear in conjunction with the rotation of the pinion gears. The sun gear is connected to the generator as the second shaft, the ring gear is connected to the motor as the third shaft, and the planetary carrier is connected to the rotating body as the first shaft. The power generation system according to claim 1, wherein the rotation control unit controls the rotation speed of the ring gear by the motor based on the parameters acquired by the acquisition unit.

4. The power conversion device comprises a first inverter (51) and a second inverter (52) that perform orthogonal power conversion. The first inverter and the second inverter have their respective high-potential and low-potential DC terminals connected to each other. The power generation system according to any one of claims 1 to 3, wherein the AC terminals of the first inverter are connected to the phase current terminals of each phase in the generator, while the AC terminals of the second inverter are connected to the power grid.

5. The planetary gear mechanism, the generator connected to the second shaft of the planetary gear mechanism, and the differential gear (24) connected to the third shaft of the planetary gear mechanism via a drive shaft (25) are on-board components that were mounted as a transaxle (13) in a hybrid vehicle. In the transaxle, the rotating body is connected to the first shaft of the planetary gear mechanism in place of the engine of the hybrid vehicle. The power generation system according to any one of claims 1 to 3, wherein the power conversion device has inverters (51, 52) that adjust the input and output of power to an on-board rotating electric machine including the generator in the hybrid vehicle.

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