Hydroelectric Power Plant

Abstract

To provide a hydroelectric power generation mechanism that can utilize energy with high efficiency. [Solution] The hydroelectric power generation mechanism comprises a first-shaft turbine having a first rotor with first rotor blades on its outer surface and a hollow first rotor connected thereto, a second-shaft turbine having a second rotor with second rotor blades on its outer surface and a second rotor connected thereto and arranged coaxially with the first-shaft turbine, and a generator. In this hydroelectric power generation mechanism, the first rotor blades are positioned upstream of the second rotor blades in an annular flow path, the generator is positioned upstream of the first-shaft turbine, a planetary gear mechanism is positioned between the generator and the first-shaft turbine, the gear at the end of the first rotor meshes with an internal gear, the second rotor is connected to a planetary carrier, and the input shaft of the generator is connected to a sun gear. During operation, the first and second rotors rotate in the same direction, and the second rotor rotates at a lower rotational speed than the first rotor.

Description

Technical Field

[0001] The present disclosure relates to a hydraulic power generation mechanism.

Background Art

[0002] In order to prevent global warming, a hydraulic power generation mechanism that generates electricity using hydraulic energy, which is a type of renewable energy, has attracted attention.

[0003] As an example of a hydraulic power generation mechanism, a schematic diagram of a general hydraulic power generation mechanism having a single-stage single-axis axial flow turbine (propeller turbine) is shown in FIG. 8.

[0004] The hydraulic power generation mechanism H has a single axial flow turbine 10, and the rotational output of the axial flow turbine 10 is transmitted to a generator 41 arranged on its upstream side to generate electricity.

[0005] The axial flow turbine 10 includes a runner 12 provided with rotating blades 11 on its outer peripheral surface, and a rotating shaft 13 connected to the runner 12 and extending upstream.

[0006] The hydraulic power generation mechanism H further includes a center body 40 arranged coaxially with the axial flow turbine 10, and an outer cylinder 60 arranged coaxially to surround the center body 40. An annular flow path FP is formed between the center body 40 and the outer cylinder 60.

[0007] In the flow path FP, an inlet guide vane 4 and rotating blades 11 are arranged in order from the upstream side in the flow direction of the water flow (see the arrow in the figure). The inlet guide vane 4 and the rotating blades 11 are each arranged at equal intervals in the circumferential direction by a predetermined number.

[0008] The center body 40 is supported by the outer cylinder 60 via a plurality of struts 45 arranged at intervals in the circumferential direction, and the generator 41 is housed inside it.

[0009] The water flowing through the annular channel FP in the direction indicated by the arrow is redirected as it passes through the inlet guide vane 4, and then passes through the rotating blades 11. At this time, the energy of the water flow is recovered and the rotating impeller 12 is driven to rotate. The output is transmitted to the generator 41 via the rotating shaft 13.

[0010] The inlet guide vane 4 is often configured to rotate in accordance with the flow rate of the incoming water, thereby changing the direction of the outgoing water flow. Similarly, the rotating blades 11, especially in single-stage axial-flow turbines, are often configured to rotate (change their pitch angle) in accordance with the direction of the water flow flowing in from the inlet guide vane 4. In this way, even in off-design conditions where the water flow rate is low compared to the design point where efficiency is highest, the orientation of the inlet guide vane 4 and rotating blades 11 is adjusted to be optimal according to the water flow conditions.

[0011] However, although some of the energy in the water flow is recovered by the axial-flow turbine 10, the remaining energy is discharged without being recovered. The energy that is discharged without being recovered corresponds to the total pressure of the discharged water flow. Total pressure corresponds to the sum of pressure (static pressure) and velocity (dynamic pressure). If more energy can be recovered from the total pressure, which is the sum of the pressure and velocity that is discharged without being recovered, then limited water resources can be utilized more effectively.

[0012] To address these problems, hydroelectric power generation mechanisms described in Patent Documents 1 and 2 are known. Patent Document 1 discloses a hydroelectric power generation mechanism that recovers energy using a multi-stage, multi-shaft axial flow turbine arranged on the same axis of rotation. Patent Document 2 discloses a hydroelectric power generation mechanism that employs a double counter-rotation mechanism in which the rotation direction of each axial flow turbine is reversed, and transmits the output to a single generator via a rotation conversion mechanism. Thus, it is known that more energy can be recovered using a multi-stage, multi-shaft axial flow turbine.

[0013] However, in the hydroelectric power generation mechanisms disclosed in Patent Documents 1 and 2, the cross-sectional area of ​​the annular flow channel where the rotating blades of the axial flow turbine are arranged is constant along the flow direction. Therefore, although it is possible to recover energy from the static pressure (pressure) and swirling velocity components of the flow, the axial flow velocity component is discharged as is and cannot be converted into pressure and recovered, which is a disadvantage.

[0014] Furthermore, in the hydroelectric power generation mechanism disclosed in Patent Document 2, despite being a double-rotating configuration, an intermediate guide vane, which should be unnecessary, is positioned between the rotating blades of the two reversing axial-flow turbines. Moreover, unlike the Francis turbine, which discharges water with a large swirling velocity component, the double-rotating mechanism is employed even though it is an axial-flow turbine with a small swirling velocity component. Adopting a double-rotating mechanism has disadvantages, such as the increased relative rotational speed due to the two rotating bodies rotating in opposite directions, which necessitates the use of differential bearings and complicates the rotating body support structure.

[0015] Furthermore, by employing a dual counter-rotating mechanism, the hydroelectric power generation mechanism disclosed in Patent Document 2 requires at least 11 gears, resulting in the inconvenience of a complex rotation conversion mechanism. Moreover, this rotation conversion mechanism only has the function of reversing the direction of rotation of the dual counter-rotating axial flow turbines to combine the output and transmit it to a single generator, and has the inconvenience of not being able to control the rotation speed of each stage of the rotating blades in accordance with changes in the water flow rate (load fluctuations) (variable speed control).

[0016] On the other hand, Patent Document 3 discloses a hydroelectric power generation mechanism having a dual counter-rotating mechanism with axial-flow / mixed-flow impellers and a centrifugal impeller. In order to achieve high efficiency with the dual counter-rotating impeller, there is a constraint that the magnitude of the load on both blades must be made approximately uniform, so a reduced diameter section is provided where the diameter of the flow path decreases toward the downstream side, and the flow path cross-sectional area is reduced. In a reaction turbine that mainly recovers pressure energy, in order to recover the energy contained in the fluid without leakage, the flow path cross-sectional area should ideally be increased and the axial flow velocity of the fluid should also be converted into pressure. Therefore, in the hydroelectric power generation mechanism of Patent Document 3, there was an inconvenience in that the flow path cross-sectional area had to be reduced because a centrifugal impeller was applied in order to aim for high efficiency by applying a dual counter-rotating mechanism.

[0017] On the other hand, when promoting the introduction of hydroelectric power, considering the utilization status of potential hydropower, large and medium-sized water sources with abundant flow rates that can accommodate large and medium-sized hydroelectric power plants have already been developed. Therefore, it is necessary to newly develop undeveloped water sources with small flow rates as small-scale distributed power plants equipped with small hydroelectric turbines or micro-turbines. Hydroelectric power generation mechanisms installed in such water sources are required to be able to efficiently and effectively utilize energy even when the water flow rate (flow conditions) changes due to the season and weather.

[0018] It is well known, as disclosed in Patent Document 4, that when the flow rate of a water turbine changes, if the rotation of the turbine's impeller blades is rotated around an axis perpendicular to the rotation axis in accordance with the change in flow rate, and the pitch angle is adjusted, the decrease in efficiency when the flow rate changes can be suppressed, and high-efficiency operation over a wide flow rate range can be achieved. Furthermore, as disclosed in Non-Patent Document 1, it is known that even in turbines with fixed rotor blades, high-efficiency operation is possible even when the flow rate of the water turbine changes by applying a variable-speed generator. When the flow rate of the water turbine changes, a constant-speed turbine with a constant rotation speed has the disadvantage of requiring the introduction of a complex movable mechanism to rotate the rotor blades and adjust the pitch angle. In addition, variable-speed turbines employing fixed rotor blades and a variable-speed generator can only be implemented with a single-stage rotor, and multi-stage variable-speed turbines where each stage rotates at a different rotation speed have not been realized.

Prior Art Documents

Patent Documents

[0019]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0020]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0021] The present invention has been made in view of the above problems, and an object of the present invention is to provide a hydraulic power generation mechanism that can efficiently and effectively utilize energy even in a small-scale water source area with unused and low-flow included water power, and also when the flow rate (flow condition) of the water flow changes due to seasons or weather.

Means for Solving the Problems

[0022] To solve the above problems, the water power generation mechanism of the first aspect of the present disclosure includes a first rotating impeller wheel having a plurality of first rotating blades on its outer peripheral surface, and a hollow first rotating shaft connected to the first rotating impeller wheel, a first axial flow water wheel composed of, a second rotating impeller wheel having a plurality of second rotating blades on its outer peripheral surface, and a second rotating shaft connected to the second rotating impeller wheel and arranged coaxially with the first axial flow water wheel, a second axial flow water wheel composed of, and a generator. In the water power generation mechanism, the plurality of first rotating blades are arranged on the upstream side of the plurality of second rotating blades in an annular flow path, the generator is arranged on the upstream side of the first axial flow water wheel, and a planetary gear mechanism is arranged between the generator and the first axial flow water wheel. The planetary gear mechanism includes an internal gear, a planetary carrier, a plurality of planetary gears, and a sun gear. A gear provided at the end of the first rotating shaft meshes with the internal gear, the second rotating shaft is connected to the planetary carrier, and the input shaft of the generator is connected to the sun gear. During operation, the first rotating shaft and the second rotating shaft rotate in the same direction, and the second rotating shaft rotates at a lower rotational speed than the first rotating shaft.

[0023] In the water power generation mechanism of the second aspect of the present disclosure, the annular flow path has a larger cross-sectional area at the position where the plurality of second rotating blades are arranged than at the position where the plurality of first rotating blades are arranged.

[0024] In the water power generation mechanism of the third aspect of the present disclosure, the second rotating shaft is divided into a driving-side rotating shaft connected to the second rotating blade and a driven-side rotating shaft connected to the planetary carrier, and a clutch is arranged between the driving-side rotating shaft and the driven-side rotating shaft.

[0025] The operation method of the first aspect of the water power generation mechanism of the present disclosure is to control the rotational speeds of the first axial flow water wheel and the second axial flow water wheel by inverter control of the rotational speed of the generator by utilizing the collinearity of the planetary gear mechanism.

[0026] In a second embodiment of the hydroelectric power generation mechanism of the present disclosure, the hydroelectric power generation mechanism is equipped with a generator-motor instead of a generator, and the method controls the rotational speeds of the first shaft turbine and the second shaft turbine by motor-driving the generator-motor and providing torque assist via a planetary gear mechanism. [Effects of the Invention]

[0027] According to the present invention, even in locations with low water flow rates, and even if the water flow rate changes significantly due to seasonal or weather changes at that location, the multi-stage rotating blades can recover the water flow energy without waste, and the planetary gear mechanism enables operation at the optimal rotational speed for each of the multi-stages due to collinear relationships, thereby maintaining high power generation efficiency as a whole system at all times. This provides a hydroelectric power generation mechanism that can serve as a small-scale distributed power source, such as a small-scale hydroelectric turbine or micro-turbine, making maximum use of limited water resources. [Brief explanation of the drawing]

[0028] [Figure 1] This is a schematic diagram of a hydroelectric power generation mechanism according to the first embodiment of this disclosure. [Figure 2] This is a system configuration diagram relating to the planetary gear mechanism in the hydroelectric power generation mechanism of the first embodiment of this disclosure. [Figure 3] This is a schematic diagram of a modified hydroelectric power generation mechanism according to the first embodiment of the present disclosure. [Figure 4] This is a velocity diagram of a planetary gear mechanism in a hydroelectric power generation mechanism according to the first embodiment of the present disclosure. [Figure 5] This is an example of a system configuration diagram and a velocity diagram of a planetary gear mechanism in a series-parallel hybrid system for passenger cars. [Figure 6] This is a schematic diagram of a hydroelectric power generation mechanism according to the second embodiment of this disclosure. [Figure 7] This is a system configuration diagram relating to the planetary gear mechanism in a hydroelectric power generation mechanism according to the second embodiment of this disclosure. [Figure 8] This is a schematic diagram of a typical hydroelectric power generation mechanism having a single-stage, single-shaft propeller turbine (axial-flow turbine). [Modes for carrying out the invention]

[0029] The hydroelectric power generation mechanism of the embodiment of this disclosure will be described below with reference to the drawings.

[0030] First, the hydroelectric power generation mechanism of the first embodiment of this disclosure will be described with reference to Figures 1 to 4.

[0031] Figure 1 is a schematic diagram of a hydroelectric power generation mechanism H according to the first embodiment of the present disclosure. The hydroelectric power generation mechanism H employs a two-stage, two-shaft axial flow turbine consisting of a first axial flow turbine 10 and a second axial flow turbine 20. The system is configured to recover fluid energy that cannot be recovered by the upstream first axial flow turbine 10 and is discharged by the downstream second axial flow turbine 20. The first axial flow turbine 10 and the second axial flow turbine 20 are arranged coaxially and rotate in the same direction at different rotational speeds. A generator 41 is located upstream of both turbines 10 and 20, and a planetary gear mechanism 30 is located between the first axial flow turbine 10 and the generator 41 in the axial direction. The rotational output of both turbines 10 and 20 is transmitted to the generator 41 via the planetary gear mechanism 30, as will be described later, and power generation is performed.

[0032] The first shaft water turbine 10 comprises a first rotating impeller 12 having first rotating blades 11 on its outer surface, and a first rotating shaft 13 connected to the first rotating impeller 12 and extending upstream. The second shaft water turbine 20 comprises a second rotating impeller 22 having second rotating blades 21 on its outer surface, and a second rotating shaft 23 connected to the second rotating impeller 22 and extending upstream. As shown in the figure, the second rotating shaft 23 extends inside the hollow first rotating shaft 13.

[0033] The hydroelectric power generation mechanism H comprises a center body 40 arranged coaxially with two axial turbines 10, 20, and an outer cylinder 60 arranged coaxially with the center body 40 so as to surround it, with an annular flow channel FP formed between the center body 40 and the outer cylinder 60.

[0034] Within the flow path FP, the inlet guide vane 4, first rotating vane 11, intermediate guide vane 5, and second rotating vane 21 are arranged in order from upstream in the direction of water flow (see arrows in the diagram). The inlet guide vane 4, first rotating vane 11, intermediate guide vane 5, and second rotating vane 21 are each arranged in predetermined numbers at equal intervals in the circumferential direction.

[0035] The center body 40 is supported by an outer cylinder 60 via a plurality of support columns 45 arranged at intervals in the circumferential direction, and houses a generator 41 inside. Furthermore, a planetary gear mechanism 30 is positioned inside the center body 40 between the first shaft water turbine 10 and the generator 41.

[0036] The planetary gear mechanism 30 consists of a sun gear 33, planetary gears 34, an internal gear 35, and a planetary carrier 36. The internal gear 35 meshes with a gear provided at the end of the first rotation shaft 13 of the first shaft waterwheel 10, and the planetary carrier 36 is connected to the end of the second rotation shaft 23 of the second shaft waterwheel 20.

[0037] The water flowing through the flow path FP in the direction indicated by the arrow is redirected as it passes through the inlet guide vane 4, and then passes through the first rotating vane 11. At this time, the energy of the water flow is recovered, and the first rotating impeller 12 is driven to rotate. Its output is transmitted to the internal gear 35 of the planetary gear mechanism 31 via the first rotating shaft 13. The water flow that flows out from the first rotating vane 12 is redirected as it passes through the intermediate guide vane 5, and then passes through the second rotating vane 21. At this time, the energy of the water flow is recovered, and the second rotating impeller 22 is driven to rotate. Its output is transmitted to the planetary carrier 36 of the planetary gear mechanism 31 via the second rotating shaft 23. In this way, the rotational outputs of the first-axis flow turbine 10 and the second-axis flow turbine 20 are transmitted to the planetary gear mechanism 30 via the first rotating shaft 13 and the second rotating shaft 23, respectively, where they are combined and then transmitted to the generator 41 via the input shaft 42.

[0038] Furthermore, the inlet guide vane 4, the first rotating vane 11, the intermediate guide vane 5, and the second rotating vane 21 do not have a rotation mechanism for changing the direction of the vane or blade. By employing rotational speed control that utilizes the collinearity of the planetary gear mechanism described later, the velocity triangle can be maintained similarly without rotating the vane or blade, thus eliminating the need for a rotation mechanism, which is a mechanically variable mechanism.

[0039] To recover energy from the water flow without leakage, the annular flow path FP from the first rotating blade 11 to the second rotating blade 21 has its cross-sectional area increased by decreasing the inner diameter and increasing the outer diameter towards the downstream side in the direction of water flow. Alternatively, to increase the cross-sectional area of ​​the flow path, the outer diameter may be kept constant and only the inner diameter decreased, or the inner diameter may be kept constant and only the outer diameter increased, towards the downstream side in the direction of water flow. By increasing the cross-sectional area of ​​the flow path, the water flow is decelerated in both the swirling and axial directions, and the kinetic energy is converted into pressure, allowing the rotating blades of the axial-flow turbine, which is a reaction turbine, to recover more energy.

[0040] Incidentally, water turbines come in various forms, and the specific speed, defined by the following equation 1, is used as an indicator to represent the characteristics and performance of each form.

[0041]

number

[0042] This specific speed is an index calculated from the flow rate, effective head, and machine rotation speed. It represents the machine rotation speed at which a hypothetical turbine with a geometrically similar shape would generate a unit output of 1 kW when operated under an effective head of 1 m. In other words, it is the machine rotation speed at which a turbine, while maintaining its geometric similarity, can be scaled down to generate an output of 1 kW under an effective head of 1 m.

[0043] It is known that there is an optimal specific speed for each type of turbine. For example, the turbine in the hydroelectric power generation mechanism of the first embodiment shown in Figure 1 is an axial flow turbine, and its mechanical rotation speed should be set to the optimal specific speed for this axial flow turbine. Furthermore, both at the design point and in off-design conditions where the turbine is operated under reduced flow rates due to seasonal and weather changes, the mechanical rotation speed of the turbine should be controlled to achieve the optimal specific speed.

[0044] Furthermore, comparing the energy (head = difference in elevation) of the water flow into the first axial-flow turbine 10 and the second axial-flow turbine 20, energy is recovered by the first rotating blade 11 of the upstream first axial-flow turbine 10. As a result, the amount of recoverable energy at the inlet of the second rotating blade 21 of the downstream second axial-flow turbine 20 decreases, and the incoming head (elevation) also decreases accordingly. Therefore, the second axial-flow turbine 20 can maintain the optimal specific speed for an axial-flow turbine by reducing its rotational speed by the amount of the decrease in elevation compared to the first axial-flow turbine 10. In other words, by controlling the rotational speed of each turbine to the optimal speed for each turbine so that the optimal specific speed can be maintained according to the different elevations at the inlet of each turbine, highly efficient operation becomes possible.

[0045] Figure 2 is a system configuration diagram of the hydroelectric power generation mechanism H of the first embodiment, in which a planetary gear mechanism 30 is applied as the rotational power transmission mechanism. As described above, the rotational power of the first shaft turbine 10 is transmitted to the internal gear 35 of the planetary gear mechanism 30 via the first rotating shaft 13, and the rotational power of the second shaft turbine 20 is transmitted to the planetary carrier 36 of the planetary gear mechanism 30 via the second rotating shaft 23. The rotational power of both turbines 10 and 20 is then combined within the planetary gear mechanism 30 and transmitted to the generator 41 via the input shaft 42.

[0046] Alternatively, as shown in Figure 3, the direction of the power transmission shaft may be changed using a bevel gear 43 within the center body 40 and transmitted to the generator 41 located outside the outer cylinder 60.

[0047] Incidentally, because the first shaft water turbine 10, the second shaft water turbine 20, and the generator 41 are connected via the planetary gear mechanism 30, a collinear relationship exists between their respective rotational speeds, based on the relationship of the number of teeth on the gears, as shown in Figure 4. A collinear relationship is a relationship in which the rotational speeds of the sun gear, planetary carrier, and internal gear plotted on the velocity diagram form a straight line, due to the fact that each gear constituting the planetary gear mechanism rotates while meshing with the others.

[0048] Here, the collinearity in planetary gear mechanisms will be explained using the example of a series-parallel hybrid system in a passenger car, with reference to Figure 5. The basic technical concept of control in modern hybrid systems, including series-parallel systems, is disclosed in Non-Patent Literature 2. The motor that drives the axle of the passenger car is coupled to the internal gear, the engine to the planetary carrier, and the generator-motor to the sun gear (see Figure 5(a)).

[0049] In a completely stopped state, the rotational speeds of the motor, engine, and generator-motor are all zero (see Figure 5(b)). During startup, the motor rotational speed is zero because the vehicle is stopped, but the positive rotational speed of the engine is increased by the torque support of the generator-motor (see Figure 5(c)). During acceleration, the motor rotational speed becomes positive because the vehicle is moving forward, the engine rotational speed also becomes positive, and the rotational speed of the generator-motor becomes even more positive, providing torque support for forward movement. This torque support state is called powering (see Figure 5(d)). In steady-state powering, although the motor rotational speed is positive because the vehicle is moving forward, the engine rotational speed and the rotational speed of the generator-motor decrease, although they remain on the positive side, in order to provide torque support appropriate for a steady state (see Figure 5(e)). In steady-state regeneration, it is assumed that the vehicle is moving forward while going downhill, the motor rotational speed is positive, torque support from the engine is not needed so the rotational speed is zero, and the rotational speed of the generator-motor becomes negative, generating electricity in a regenerative state and charging the battery (see Figure 5(f)).

[0050] The hydroelectric power generation mechanism H of the first embodiment of this disclosure utilizes the collinearity of the planetary gear mechanism described above. This will be explained with reference to Figure 4.

[0051] At the design point, both the upstream first shaft turbine 10 and the downstream second shaft turbine 20 recover energy from the water flow, resulting in positive rotational speeds. The generator 41 rotates at a negative rotational speed, generating electricity equivalent to this regenerated energy (see Figure 4(a)). On the other hand, in the off-design state, the absolute values ​​of the rotational speeds of the turbines 10, 20 and the generator 41 decrease by the amount that the energy of the water flow decreases (see Figure 4(b)). Furthermore, if the off-design state progresses and the load reaches its lower limit, the rotational speed of the generator 41 is controlled so that the second shaft turbine 20's rotational speed is zero or at a speed that does not hinder energy recovery, in order to prevent it from becoming a load resistance (see Figure 4(c)). Furthermore, in situations where stable operation is difficult by simply recovering the energy of the water flow, such as during startup, power is supplied to the generator to operate it as an electric motor, and by "powering" it at a positive rotational speed, it becomes possible to control the rotational speeds of the first axle water turbine 10 and the second axle water turbine 20 by torque support (see Figure 4(d)).

[0052] By changing the rotational speed of the generator 41 using inverter control, the mechanical rotational speeds of the collinear first-axis water turbine 10 and the second-axis water turbine 20 can be changed and controlled to different values. In this way, by controlling the mechanical rotational speed of each turbine to its optimal speed, the optimal specific speed can be maintained according to the different heads at the inlet of each turbine, enabling highly efficient operation.

[0053] If low torque output reduces starting performance or performance in the low-load off-design region, a generator-motor may be used as the generator 41. By using a generator-motor, torque assist is provided, reducing the load on the rotating blades and ensuring starting performance and operability. While hydroelectric power generation mechanisms normally generate electricity by recovering energy from the water flow, torque assist uses electricity already generated and stored in a power storage device or grid power to operate the generator-motor as a motor, applying torque to the first-axis water turbine 10 and the second-axis water turbine 20 to support their drive. Regeneration is when the turbine recovers energy from the water flow and rotates to passively generate electricity, whereas motoring is when the turbine is actively driven to rotate against the water flow. By using a generator-motor, operability is ensured by this motoring during starting, when operability deteriorates. This makes it possible to ensure a wide range of operating stability for the multi-stage variable-speed water turbine, including during starting.

[0054] A hydroelectric power generation mechanism according to a second embodiment of the present invention will be described with reference to Figures 6 and 7.

[0055] In the hydroelectric power generation mechanism H of the second embodiment, the second rotating shaft 23 of the second shaft turbine 20 is divided into a driving rotating shaft 24 and a driven rotating shaft 25, and a clutch 26 is placed between these two rotating shafts 24 and 25. In this hydroelectric power generation mechanism H, when the water flowing into the second shaft turbine 20 has recoverable energy, the mechanism operates with the driving rotating shaft 24 and the driven rotating shaft 25 connected by the clutch 26 (i.e., the state of the first embodiment). On the other hand, if the water flow rate decreases drastically and the water flowing into the second shaft turbine 20 does not have recoverable energy, the connection between the driving rotating shaft 24 and the driven rotating shaft 25 by the clutch 26 is disconnected so that the second shaft turbine 20 does not become a load resistance. As a result, the hydroelectric power generation mechanism H operates with only the first shaft turbine 10, enabling operation in a wider range of off-design conditions. [Explanation of Symbols]

[0056] FP annular channel H Hydroelectric Power Plant 4 Entrance Information Wing 5 Intermediate guide wings 10 First axial flow turbine 11. First rotating blade 12. First Rotating Impeller 13. First axis of rotation 20 Second axial flow turbine 21 Second Rotating Blade 22. Second Rotating Impeller 23. Second rotation axis 24 Drive side rotating shaft 25 Driven rotating shaft 26 Clutch 30 Planetary gear mechanism 33 Sun Gear 34 Planetary gears 35 Internal gear 36 Planetary Carriers 40 Center Body 41 Generator 42 (Generator) Input shaft 43 Bevel gear 45 Post 60 Outer cylinder

Claims

1. A first shaft water turbine comprising a first rotating impeller having a plurality of first rotating blades on its outer surface, and a hollow first rotating shaft connected to the first rotating impeller, A second-shaft waterwheel comprising a second impeller having a plurality of second rotating blades on its outer circumferential surface, and a second rotating shaft connected to the second impeller and arranged coaxially with the first-shaft waterwheel, A generator and A hydroelectric power generation mechanism equipped with, The plurality of first rotating blades are arranged upstream of the plurality of second rotating blades in an annular flow path. The generator is located upstream of the first shaft-flow turbine, A planetary gear mechanism is arranged between the generator and the first shaft water turbine. The planetary gear mechanism comprises an internal gear, a planetary carrier, a plurality of planetary gears, and a sun gear. A gear provided at the end of the first rotating shaft meshes with the internal gear, and the second rotating shaft is connected to the planetary carrier, and the input shaft of the generator is connected to the sun gear. During operation of the hydroelectric power generation mechanism, the first and second rotating shafts rotate in the same direction, and the second rotating shaft rotates at a lower rotational speed than the first rotating shaft. Hydroelectric power plant.

2. The annular flow path has a larger cross-sectional area at the position where the plurality of second rotating blades are arranged than at the position where the plurality of first rotating blades are arranged. The hydroelectric power generation mechanism according to feature 1.

3. The second rotating shaft is divided into a driving-side rotating shaft connected to the second rotating impeller and a driven-side rotating shaft connected to the planetary carrier. A clutch is positioned between the driving side rotating shaft and the driven side rotating shaft. The hydroelectric power generation mechanism according to feature 2.

4. A method for operating a hydroelectric power generation mechanism according to any one of claims 1 to 3, The rotational speeds of the first shaft waterwheel and the second shaft waterwheel are controlled by inverter control of the generator's rotational speed, utilizing the collinearity of the planetary gear mechanism. A method characterized by the following:

5. A method for operating a hydroelectric power generation mechanism according to any one of claims 1 to 3, The aforementioned hydroelectric power generation mechanism is equipped with a generator-motor instead of the generator, The method controls the rotational speeds of the first shaft waterwheel and the second shaft waterwheel by driving the generator motor and providing torque assist via the planetary gear mechanism. A method characterized by the following:

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