Hybrid servo system

Abstract

To provide a hybrid servo system that can achieve downsizing.SOLUTION: In a hybrid servo system, a hydraulic circuit section has a two-way pump, an accumulator, a pilot check valve for supplying accumulated oil, and a solenoid valve for supplying accumulated oil, and drives a hydraulic servo motor that operates guide vanes of a water turbine. The hydraulic servo motor has a cylinder whose internal space is divided into a first hydraulic chamber and a second hydraulic chamber by a piston. The two-way pump supplies hydraulic oil to the first hydraulic chamber via an opening-side pilot valve during opening operation, and to the second hydraulic chamber via a closing-side pilot valve during closing operation. In sudden closing operation, by the operation of the servo valve for supplying accumulated oil, the hydraulic oil accumulated in the accumulator is supplied to the second hydraulic chamber via the pilot check valve for supplying accumulated oil and the closing-side pilot valve, and the hydraulic oil is discharged from the first hydraulic chamber to an oil collection tank via the opening-side pilot valve.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a hybrid servo system. [Background technology]

[0002] In hydroelectric power plants, the operation of the guide vanes of the water turbines is controlled, for example, by a hybrid servo system.

[0003] For example, when a speed control operation is being performed on a water turbine, if the deviation in the water turbine's rotational speed, etc. becomes large, the hybrid servo system supplies hydraulic oil from the accumulator to the hydraulic servo motor to adjust the opening of the guide vanes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6298207 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-317745 [Patent Document 3] Patent Publication No. 2021-017861 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the above hybrid servo system, when a sudden closing operation (emergency closing operation) is performed to reduce the guide vane opening more rapidly than in a normal closing operation in order to bring the turbine rotation speed to the set value in a short time when there is a large deviation in the turbine rotation speed, a large amount of hydraulic oil needs to be supplied from the accumulator to the hydraulic servo motor. Similarly, when a sudden closing operation is performed to respond to the occurrence of an abnormality, a large amount of hydraulic oil needs to be supplied from the accumulator to the hydraulic servo motor in order to stabilize the turbine rotation speed in a short time.

[0006] For the reasons described above, conventional hybrid servo systems require a large-capacity accumulator, which can lead to a large-sized hydraulic device including the accumulator, making it difficult to reduce the size of the hybrid servo system.

[0007] Therefore, the problem to be solved by the present invention is to provide a hybrid servo system that can be easily downsized. [Means for solving the problem]

[0008] A hybrid servo system according to an embodiment includes a hydraulic circuit unit and a control unit, and controls the operation of a hydraulic turbine. The hydraulic turbine includes a runner that rotates when water is supplied through guide vanes, and a generator configured to generate electricity through the rotation of the runner, with the generator outputting electric power to a power grid. In the hybrid servo system, the hydraulic circuit unit drives a hydraulic servo motor for closing and opening the guide vanes, and the control unit controls the operation of the hydraulic circuit unit. The hydraulic servo motor has a cylinder. The cylinder houses a piston attached to an operating rod that operates the guide vanes in an internal space, and the internal space is divided by the piston into a first hydraulic chamber and a second hydraulic chamber. The hydraulic circuit unit includes a bidirectional pump, an accumulator, an accumulator oil supply pilot check valve, and an accumulator oil supply solenoid valve. The bidirectional pump is configured to supply hydraulic oil to the first hydraulic chamber via an opening pilot valve when performing an opening operation, and to supply hydraulic oil to the second hydraulic chamber via a closing pilot valve when performing a closing operation. The accumulator is configured to store hydraulic oil. The accumulator oil supply pilot check valve is installed in an oil passage through which hydraulic oil flows from the accumulator to the closing pilot valve. When performing a sudden closing operation of the guide vane, the accumulator oil supply solenoid valve supplies hydraulic oil stored in the accumulator to the pilot port of the accumulator oil supply pilot check valve, the pilot port of the opening pilot valve, and the pilot port of the closing pilot valve. When performing a sudden closing operation, hydraulic oil stored in the accumulator is supplied to the second hydraulic chamber via the accumulator oil supply pilot check valve and the closing pilot valve, and hydraulic oil is discharged from the first hydraulic chamber to the oil collection tank via the opening pilot valve. When power is normally output from the generator and an abnormality occurs in the turbine or in the power system, the control unit controls the operation of the accumulator oil supply solenoid valve to perform the sudden closing operation. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a partial cross-sectional view schematically illustrating an example of a water turbine 90 in an embodiment. [Figure 2] FIG. 2 is a diagram showing a hybrid servo system for driving guide vanes 95 of a water turbine 90 in an embodiment. [Figure 3A] FIG. 3A is a diagram schematically showing a state in which the guide vane 95 performs an opening operation in the hybrid servo system of the embodiment. [Figure 3B] FIG. 3B is a diagram that schematically shows a state in which the guide vane 95 performs a closing operation in the hybrid servo system of the embodiment. [Figure 3C] FIG. 3C is a diagram schematically showing a state in which a sudden closing operation is performed on the guide vane 95 in the hybrid servo system of the embodiment. [Figure 4] FIG. 4 is a functional block diagram showing a detector 800 and a controller 900 in the hybrid servo system of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] [A] Overview of the Waterwheel 90 Fig. 1 is a partial cross-sectional view schematically illustrating an example of a water turbine 90 in an embodiment. Fig. 1 shows a longitudinal cross section (a plane including the center of rotation).

[0011] The water turbine 90 is, for example, a Francis type water turbine, and as shown in Figure 1, has a runner 91, a main shaft 92, an upper cover 93, a lower cover 94, guide vanes 95, a casing 96, an exhaust pipe 97, and a generator 98, and is configured to output the generated electricity to a power system 700 (load).

[0012] [A-1] Runner 91 In the water turbine 90, the runner 91 has a runner crown 91a, a runner band 91b, and runner vanes 91c, and is configured to rotate together with the main shaft 92. The runner 91 has the runner crown 91a and the runner band 91b arranged with a gap between them. In the runner 91, a plurality of runner vanes 91c are provided between the runner crown 91a and the runner band 91b.

[0013] [A-2] Main shaft 92 The main shaft 92 has a longitudinal direction aligned with the vertical direction, and the lower end of the main shaft 92 is connected to the upper surface of a runner crown 91 a that constitutes the runner 91 .

[0014] [A-3] Top cover 93 The upper cover 93 is provided above the runner 91. The main shaft 92 passes through the center of the upper cover 93, and the upper cover 93 covers the upper surface of the runner crown 91a on the side of the outer circumferential surface of the main shaft 92.

[0015] [A-4] Lower cover 94 The lower cover 94 is provided below the runner 91. A discharge pipe 97 is provided below the lower cover 94, and the outer periphery of the discharge pipe 97 covers the lower surface of the runner band 91b.

[0016] [A-5] Guide Vane 95 The guide vanes 95 are installed on the outer periphery of the runner 91 and are connected to the outer surfaces of the upper cover 93 and the lower cover 94. The guide vanes 95 are configured to adjust the flow rate of water flowing into the runner 91 by changing the opening degree.

[0017] [A-6] Casing 96 The casing 96 has a doughnut shape and is disposed on the outer periphery of the guide vane 95 .

[0018] [A-7] Discharge pipe 97 The discharge pipe 97 is provided below the runner 91 and is connected to the lower cover 94 .

[0019] [A-8] Generator 98 The generator 98 is connected to an upper portion of the main shaft 92. The generator 98 is configured to generate electricity when the main shaft 92 is rotated.

[0020] When the water turbine 90 is operating to generate power, water is supplied from the casing 96 to the runner 91 via the guide vanes 95. This causes water to flow from the outer periphery (side) of the runner 91 to the inside, causing the runner 91 to rotate together with the main shaft 92. The rotation of the main shaft 92 then drives the generator 98, which generates power. The power generated by the generator 98 is output to the power grid 700.

[0021] During power generation operation, water flows in from the outer periphery of the runner 91, flows between the runner crown 91a and the runner band 91b in the runner 91, then flows from above to below, and is discharged to the discharge pipe 97.

[0022] [B] Overview of the hybrid servo system configuration FIG. 2 is a diagram showing a hybrid servo system for driving guide vanes 95 of a water turbine 90 in an embodiment.

[0023] [B-1] Hydraulic servo motor 50 2, the hydraulic servomotor 50 includes an operating rod 51, a cylinder 52, and a piston 55. In the hydraulic servomotor 50, the operating rod 51 for operating the guide vane 95 is provided with the piston 55, and the piston 55 is housed in the cylinder 52. The hydraulic servomotor 50 is configured such that the operating rod 51 operates the guide vane 95 by driving the piston 55 inside the cylinder 52 by the action of hydraulic oil.

[0024] [B-1-1] Operating rod 51 Specifically, the operating rod 51 is a rod-shaped body, one end of which is connected to the guide vane 95 and the other end of which is connected to the piston 55 .

[0025] [B-1-2] Cylinder 52 The cylinder 52 accommodates a piston 55 in an internal space C52. The internal space C52 of the cylinder 52 is divided by the piston into a first hydraulic chamber C52a and a second hydraulic chamber C52b.

[0026] In the cylinder 52, the first hydraulic chamber C52a is provided with a first hydraulic oil port P52a, and the second hydraulic chamber C52b is provided with a second hydraulic oil port P52b.

[0027] [B-1-3] Piston 55 The piston 55 is connected to the operating rod 51 in the internal space C52 of the cylinder 52. The piston 55 is configured to slide in the internal space C52 of the cylinder 52 in accordance with the pressure difference of the hydraulic oil between the first hydraulic chamber C52a and the second hydraulic chamber C52b.

[0028] Specifically, when the guide vane 95 performs an opening operation, the piston 55 slides from the first hydraulic chamber C52a side to the second hydraulic chamber C52b side. When the guide vane 95 performs a closing operation, the piston 55 slides from the second hydraulic chamber C52b side to the first hydraulic chamber C52a side.

[0029] [B-1-4] Displacement detection unit 500 The hydraulic servo motor 50 is further provided with a displacement detection unit 500. The displacement detection unit 500 is, for example, a limit switch, and is provided to detect the amount of displacement of the opening of the guide vane 95 (including fully closed and no-load opening).

[0030] [B-2] Hybrid Servo System In this embodiment, the hybrid servo system includes a hydraulic circuit section 100, a detection section 800, and a control section 900, as shown in FIG.

[0031] [B-2-1] Hydraulic circuit section 100 In the hybrid servo system, the hydraulic circuit section 100 includes a bidirectional pump 110, an oil collection tank 130, and an accumulator 140. The hydraulic circuit section 100 also includes an opening pilot valve V30a, a closing pilot valve V30b, an accumulated oil supply pilot check valve V33, and an accumulated oil supply solenoid valve V35.

[0032] In addition, the hydraulic circuit section 100 is provided with an opening pilot check valve V13a, a closing pilot check valve V13b, an opening relief valve V14a, a closing relief valve V14b, an opening check valve V36a, and a closing check valve V36b.

[0033] The components of the hydraulic circuit unit 100 are configured so that hydraulic oil flows through oil passages L11 to L16, L11a, L12a, L33, L33b, L36, L36a, L351, L352, L353, L130, and L140.

[0034] Each part constituting the hydraulic circuit section 100 will be explained in order.

[0035] [B-2-1-1] Two-way pump 110 The bidirectional pump 110 is, for example, a reversible rotary pump, and has a port a (first bidirectional pump port) and a port b (second bidirectional pump port). The bidirectional pump 110 is configured to discharge hydraulic oil from each of the ports a and b.

[0036] In this embodiment, the bidirectional pump 110 is configured to supply hydraulic oil from port a to the first hydraulic chamber C52a via the opening pilot valve V30a when performing an opening operation, and to supply hydraulic oil from port b to the second hydraulic chamber C52b via the closing pilot valve V30b when performing a closing operation.

[0037] [B-2-1-2] Oil collection tank 130 The oil collection tank 130 is, for example, a tank configured to store hydraulic oil.

[0038] [B-2-1-3] Accumulator 140 The accumulator 140 is configured to store and release hydraulic fluid in response to the pressure of a pressurized gas such as nitrogen.

[0039] [B-2-1-4] Oil passage L11 One end of the oil passage L11 is connected to port a of the bidirectional pump 110, and the other end is configured to communicate with the first hydraulic oil port P52a of the cylinder 52. The oil passage L11 is provided with a branch portion J11a, a branch portion J11b, a branch portion J11c, and a branch portion J11d, in this order from the bidirectional pump 110 side toward the cylinder 52 side.

[0040] [B-2-1-5] Opening side pilot valve V30a An opening pilot valve V30a is provided in the oil passage L11 between the branching points J11c and J11d. The opening pilot valve V30a is, for example, a 3-port 2-position directional control valve and includes a port 1, a port 2, and a port 3.

[0041] The open-side pilot valve V30a is configured to switch between a state in which ports 1 and 2 are in communication with each other and a state in which ports 1 and 3 are in communication with each other, depending on the pressure difference of the hydraulic oil applied to the pilot port.

[0042] Details will be described later, but in this embodiment, when the opening pilot valve V30a performs a sudden closing operation on the guide vane 95, it switches from a communication state between port 1 and port 2 to a communication state between port 1 and port 3.

[0043] [B-2-1-6] Oil passage L12 One end of the oil passage L12 is connected to port b of the bidirectional pump 110, and the other end is configured to communicate with a second hydraulic oil port P52b of the cylinder 52. In the oil passage L12, a branch portion J12a, a branch portion J12b, a branch portion J12c, and a branch portion J12d are provided in this order from the bidirectional pump 110 side toward the cylinder 52 side.

[0044] [B-2-1-7] Close side pilot valve V30b A closing pilot valve V30b is provided in oil passage L12 between branching point J12c and branching point J12d. The closing pilot valve V30b is, for example, a 3-port 2-position directional control valve that includes a port 1, a port 2, and a port 3.

[0045] The closing pilot valve V30b is configured to switch between a state in which ports 1 and 2 are in communication with each other and a state in which ports 1 and 3 are in communication with each other, depending on the pressure difference of the hydraulic oil applied to the pilot port.

[0046] Details will be described later, but in this embodiment, when the closing side pilot valve V30b performs a sudden closing operation on the guide vane 95, it switches from a communication state between port 1 and port 2 to a communication state between port 1 and port 3.

[0047] [B-2-1-8] Oil passage L13 One end of the oil passage L13 is connected to a branched portion J11b of the oil passage L11, and the other end is connected to a branched portion J12b of the oil passage L12. The oil passage L13 is provided with a branched portion J13.

[0048] [B-2-1-9] Opening side pilot check valve V13a An opening pilot check valve V13a is provided in the oil passage L13 between the branch point J11b and the branch point J13.

[0049] The opening pilot check valve V13a has an IN port on the branch J13 side and an OUT port on the branch J11d side, and when the pressure of hydraulic oil applied to the pilot port is equal to or lower than a set value, hydraulic oil flows from the IN port to the OUT port.The opening pilot check valve V13a is configured so that when the pressure of hydraulic oil applied to the pilot port exceeds the set value, hydraulic oil flows back from the OUT port to the IN port.

[0050] [B-2-1-10] Close side pilot check valve V13b A close-side pilot check valve V13b is provided in the oil passage L13 between the branch point J12b and the branch point J13.

[0051] The closing pilot check valve V13b has an IN port on the branch J13 side and an OUT port on the branch J12b side, and when the pressure of hydraulic oil applied to the pilot port is equal to or lower than a set value, hydraulic oil flows from the IN port to the OUT port.The closing pilot check valve V13b is configured so that when the pressure of hydraulic oil applied to the pilot port exceeds the set value, hydraulic oil flows back from the OUT port to the IN port.

[0052] [B-2-1-11] Oil passage L11a, oil passage L12a One end of the oil passage L11a is connected to a branch J11a of the oil passage L11, and the other end is connected to a pilot port of the closing pilot check valve V13b. One end of the oil passage L12a is connected to a branch J12a of the oil passage L12, and the other end is connected to a pilot port of the opening pilot check valve V13a.

[0053] [B-2-1-12] Oil passage L14 One end of the oil passage L14 is connected to a branched portion J11c of the oil passage L11, and the other end is connected to a branched portion J12c of the oil passage L12. The oil passage L14 is provided with a branched portion J14.

[0054] [B-2-1-13] Opening side relief valve V14a An opening relief valve V14a is provided in the oil passage L14 between the branch point J11c and the branch point J14. The opening relief valve V14a is configured to open when the pressure of the hydraulic oil exceeds a set value.

[0055] [B-2-1-14] Closing side relief valve V14b A closing relief valve V14b is provided in oil passage L14 between branch point J12c and branch point J14. The closing relief valve V14b is configured to open when the pressure of the hydraulic oil exceeds a set value.

[0056] [B-2-1-15] Oil passage L130, oil passage L15, oil passage L16 One end of oil passage L130 is connected to port 3 of the opening pilot valve V30a, and the other end is connected to the oil collection tank 130. Oil passage L130 is provided with branch portions J130a, J130b, and J130c, which are arranged in this order from the oil collection tank 130 side toward the opening pilot valve V30a side. Oil passage L15 has one end connected to branch portion J13 and the other end connected to branch portion J130a. Oil passage L16 has one end connected to branch portion J14 and the other end connected to branch portion J130b.

[0057] [B-2-1-16] Oil passage L140 One end of oil passage L140 is connected to port 3 of the closing pilot valve V30b, and the other end is connected to the accumulator 140. Branch portions J140a and J140b are provided in oil passage L140, in that order, from the accumulator 140 side toward the closing pilot valve V30b side. A gate valve SV32 is provided in oil passage L140 between the accumulator 140 and branch portion J140a.

[0058] [B-2-1-17] Pilot check valve for storage oil supply V33 An accumulator oil supply pilot check valve V33 is provided in the oil passage L140 between the branch point J140b and the closing pilot valve V30b. That is, the accumulator oil supply pilot check valve V33 is provided in the oil passage L140 through which hydraulic oil flows from the accumulator 140 to the closing pilot valve V30b.

[0059] The accumulator oil supply pilot check valve V33 has an IN port on the closing pilot valve V30b side and an OUT port on the branch J140b side, and when the pressure of hydraulic oil applied to the pilot port is equal to or lower than a set value, hydraulic oil flows from the IN port to the OUT port.The accumulator oil supply pilot check valve V33 is configured so that when the pressure of hydraulic oil applied to the pilot port exceeds the set value, hydraulic oil flows back from the OUT port to the IN port.

[0060] Although details will be described later, in this embodiment, the stored oil supply pilot check valve V33 is configured so that hydraulic oil flows back from the OUT side port to the IN side port when the guide vane 95 performs a quick closing operation.

[0061] [B-2-1-18] Oil passage L33, oil passage L33b One end of the oil passage L33 is connected to the pilot port of the accumulator-oil supply pilot check valve V33, and the other end is connected to the pilot port of the opening-side pilot valve V30a. Branches J33a and J33b are provided in the oil passage L33, in this order, from the accumulator-oil supply pilot check valve V33 side toward the opening-side pilot valve V30a side. One end of the oil passage L33b is connected to branch J36b of the oil passage L33, and the other end is connected to the pilot port of the closing-side pilot valve V30b.

[0062] [B-2-1-19] Oil passage L36, oil passage L36a One end of the oil passage L36 is connected to a branch point J140a of the oil passage L140, and the other end is connected to a branch point J12d of the oil passage L12. The oil passage L36 is provided with a branch point J36. One end of the oil passage L36a is connected to a branch point J36 of the oil passage L36, and the other end is connected to a branch point J11d of the oil passage L11.

[0063] [B-2-1-20] Opening check valve V36a An opening check valve V36a is provided in the oil passage L36a. The opening check valve V36a has an IN port on the branch J36 side and an OUT port on the branch J11d side, and is configured so that hydraulic oil flows from the IN port to the OUT port.

[0064] [B-2-1-21] Close side check valve V36b A closing check valve V36b is provided in oil passage L36 between branch J36 and branch J12d. The closing check valve V36b has an IN port on the branch J36 side and an OUT port on the branch J12d side, and is configured so that hydraulic oil flows from the IN port to the OUT port.

[0065] [B-2-1-22] Pressure storage oil supply solenoid valve V35 The stored oil supply solenoid valve V35 is, for example, a three-port two-position directional control valve, and includes a port 1, a port 2, and a port 3.

[0066] The accumulator oil supply solenoid valve V35 is configured so that, in the energized state EG, communication is established between port 1 and port 2. The accumulator oil supply solenoid valve V35 is configured so that, in the de-energized state DG, communication is established between port 1 and port 3.

[0067] Although details will be described later, in this embodiment, when the guide vane 95 is suddenly closed, the stored oil supply solenoid valve V35 changes from the excited state EG to the de-energized state DG, and switches from a communication state between port 1 and port 2 to a communication state between port 1 and port 3.

[0068] [B-2-1-23] Oil path L351, oil path L352, oil path L353 One end of oil passage L351 is connected to port 1 of the accumulator oil supply solenoid valve V35 and the other end is connected to branch J33a of oil passage L33. One end of oil passage L352 is connected to port 2 of the accumulator oil supply solenoid valve V35 and the other end is connected to branch J130c of oil passage L130. One end of oil passage L353 is connected to port 3 of the accumulator oil supply solenoid valve V35 and the other end is connected to branch J140b of oil passage L140.

[0069] [B-2-2] Detection unit 800 The detection unit 800 is configured to include a device that outputs a detection signal S800 to the control unit 900.

[0070] [B-2-3] Control unit 900 The control unit 900 includes a computing unit (not shown) and a memory device (not shown), and is configured to control the operation of the hydraulic circuit unit 100 by the computing unit performing arithmetic processing using a program stored in the memory device. The control unit 900 receives, for example, an operation command signal input by an operator to an operation device (not shown). In addition, the control unit 900 receives a detection signal S800 from the detection unit 800. The control unit 900 outputs a control signal to the hydraulic circuit unit 100 based on various signals input from various units (sensors, etc.), and controls the operation of the hydraulic servo motor 50 to operate the guide vane 95.

[0071] For example, the control unit 900 causes the guide vanes 95 to perform a normal opening operation and a normal closing operation in order to perform a speed control operation of the water turbine 90. The normal opening operation and the normal closing operation are performed by the control unit 900 controlling the operation of the bidirectional pump 110.

[0072] In this embodiment, the control unit 900 outputs a quick-closing operation command S900 to the hydraulic circuit unit 100 in response to a detection signal S800 input from the detection unit 800, thereby causing the guide vanes 95 to perform a quick-closing operation. The quick-closing operation is an operation that reduces the opening degree of the guide vanes 95 at a speed faster than that of a normal closing operation. In this embodiment, the quick-closing operation is performed by the control unit 900 controlling the operation of the stored-oil supply solenoid valve V35 when an abnormality occurs in the hydraulic turbine 90 or in the power system 700 while power is being normally output from the generator 98.

[0073] [C] Operation overview In the hydraulic circuit section 100 of this embodiment, the following describes how the control section 900 adjusts the opening of the guide vane 95. Here, the guide vane 95 will be described in order for a normal opening operation (case 1), a normal closing operation (case 2), and a sudden closing operation (case 3).

[0074] [C-1] Normal opening operation (Case 1) First, a normal opening operation (Case 1) will be described.

[0075] 3A is a diagram schematically illustrating a state in which the guide vane 95 performs an opening operation in the hybrid servo system of the embodiment. In FIG. 3A, the outline of the flow of hydraulic oil is also indicated by thick solid arrows.

[0076] 3A, when the guide vane 95 is to perform a normal opening operation (case 1), the control unit 900 sets the accumulator oil supply solenoid valve V35 to an excited state EG, thereby blocking communication between port 1 and port 3. As a result, the accumulator oil supply solenoid valve V35 blocks the supply of hydraulic oil stored in the accumulator 140 to the pilot port of the accumulator oil supply pilot check valve V33, the pilot port of the opening-side pilot valve V30a, and the pilot port of the closing-side pilot valve V30b.

[0077] As a result, in the accumulator oil supply pilot check valve V33, the pressure of the hydraulic oil applied to the pilot port is equal to or less than the set value, so that backflow of hydraulic oil from the OUT port to the IN port does not occur. The opening pilot valve V30a establishes communication between ports 1 and 2, so that port a of the bidirectional pump 110 and the first hydraulic chamber C52a of the cylinder 52 are communicated via the opening pilot valve V30a. The closing pilot valve V30b establishes communication between ports 1 and 2, so that port b of the bidirectional pump 110 and the second hydraulic chamber C52b of the cylinder 52 are communicated via the closing pilot valve V30b.

[0078] In the above state, the two-way pump 110 sucks up hydraulic oil from port b and discharges it from port a to the oil passage L11. The hydraulic oil discharged from the two-way pump 110 to the oil passage L11 is supplied to the first hydraulic chamber C52a of the cylinder 52 that constitutes the hydraulic servomotor 50 via the open-side pilot valve V30a.

[0079] The pressure in the first hydraulic chamber C52a of the cylinder 52 increases due to the supply of hydraulic oil. As a result, the piston 55 moves from the first hydraulic chamber C52a side to the second hydraulic chamber C52b side in the internal space C52 of the cylinder 52. As a result, the guide vane 95 performs a normal opening operation, and the opening degree of the guide vane 95 increases in accordance with the pressure difference.

[0080] As the piston 55 moves from the first hydraulic chamber C52a to the second hydraulic chamber C52b, hydraulic oil flows out from the second hydraulic chamber C52b to the oil passage L12. The hydraulic oil that flows out from the second hydraulic chamber C52b to the oil passage L12 passes through the closing pilot valve V30b and then returns to port b of the two-way pump 110.

[0081] [C-2] Normal closing operation (Case 2) Next, a normal closing operation (Case 2) will be described.

[0082] 3B is a diagram schematically illustrating a state in which the guide vane 95 performs a closing operation in the hybrid servo system of the embodiment. In FIG. 3B, similar to FIG. 3A, the outline of the flow of hydraulic oil is also indicated by thick solid arrows.

[0083] As shown in FIG. 3B, the control unit 900 controls each part when the guide vane 95 performs a normal closing operation (case 2) in the same way as when the guide vane 95 performs a normal opening operation (case 1) (see FIG. 3A).

[0084] That is, the stored-oil supply solenoid valve V35, the opening-side pilot valve V30a, and the closing-side pilot valve V30b are in the same states as when the guide vane 95 performs a normal opening operation (Case 1). As a result, port a of the two-way pump 110 and the first hydraulic chamber C52a of the cylinder 52 are in a state of communication via the opening-side pilot valve V30a. Also, port b of the two-way pump 110 and the second hydraulic chamber C52b of the cylinder 52 are in a state of communication via the closing-side pilot valve V30b.

[0085] However, when performing a normal closing operation, unlike when performing a normal opening operation, the control unit 900 controls the bidirectional pump 110 to suck up hydraulic oil from port a and discharge the hydraulic oil from port b to oil passage L14. As a result, the hydraulic oil discharged from the bidirectional pump 110 to oil passage L12 is supplied to the second hydraulic chamber C52b of the cylinder 52 that constitutes the hydraulic servomotor 50 via the closing-side pilot valve V30b.

[0086] The pressure in the second hydraulic chamber C52b of the cylinder 52 increases due to the supply of hydraulic oil. As a result, the piston 55 moves from the second hydraulic chamber C52b side to the first hydraulic chamber C52a side in the internal space C52 of the cylinder 52. As a result, the guide vane 95 performs a normal closing operation, and the opening degree of the guide vane 95 decreases in accordance with the pressure difference.

[0087] As the piston 55 moves from the second hydraulic chamber C52b side to the first hydraulic chamber C52a side, the hydraulic oil flows out from the first hydraulic chamber C52a to the oil passage L11. The hydraulic oil that flows out from the first hydraulic chamber C52a to the oil passage L11 passes through the opening pilot valve V30a and then returns to port a of the two-way pump 110.

[0088] [C-3] Sudden closing operation (Case 3) Next, a case where a sudden closing operation is performed (Case 3) will be described.

[0089] 3C is a diagram schematically illustrating a state in which the hybrid servo system of the embodiment performs a sudden closing operation on the guide vane 95. In FIG. 3C, similar to FIG. 3A, the outline of the flow of hydraulic oil is also indicated by thick solid arrows.

[0090] As shown in FIG. 3C, when a sudden closing operation is performed (case 3), the control unit 900 controls the pressurized oil supply solenoid valve V35 to a state different from that when a normal opening operation is performed (case 1) and when a normal closing operation is performed (case 2).

[0091] Specifically, by switching the stored-oil supply solenoid valve V35 from the energized state EG to the de-energized state DG, the stored-oil supply solenoid valve V35 establishes communication between port 1 and port 3. As a result, the hydraulic oil stored in the accumulator 140 acts on the pilot port of the stored-oil supply pilot check valve V33, the pilot port of the opening-side pilot valve V30a, and the pilot port of the closing-side pilot valve V30b via the stored-oil supply solenoid valve V35.

[0092] As a result, in the accumulator oil supply pilot check valve V33, the pressure of hydraulic oil applied to the pilot port exceeds the set value, allowing backflow of hydraulic oil from the OUT port to the IN port. In the opening pilot valve V30a, the pressure of hydraulic oil applied to the pilot port exceeds the set value, so port 2 and port 3 are connected. Similarly, in the closing pilot valve V30b, the pressure of hydraulic oil applied to the pilot port exceeds the set value, so port 2 and port 3 are connected.

[0093] Accordingly, the hydraulic oil stored in the accumulator 140 passes through the stored oil supply pilot check valve V33 and the closing pilot valve V30b in this order, and is supplied to the second hydraulic chamber C52b of the cylinder 52 that constitutes the hydraulic servomotor 50.

[0094] The pressure in the second hydraulic chamber C52b of the cylinder 52 increases due to the supply of hydraulic oil. As a result, the piston 55 moves from the second hydraulic chamber C52b side to the first hydraulic chamber C52a side in the internal space C52 of the cylinder 52. As a result, the guide vane 95 performs a quick closing operation.

[0095] As the piston 55 moves from the second hydraulic chamber C52b side to the first hydraulic chamber C52a side, the hydraulic oil flows out from the first hydraulic chamber C52a to the oil passage L11. The hydraulic oil that flows out from the first hydraulic chamber C52a to the oil passage L11 is discharged to the oil collection tank 130 via the opening pilot valve V30a and stored there.

[0096] In the hydraulic circuit section 100 of this embodiment, the opening pilot check valve V13a, the closing pilot check valve V13b, the opening relief valve V14a, the closing relief valve V14b, the opening check valve V36a, and the closing check valve V36b are each provided to keep the pressure of the hydraulic oil in the hydraulic circuit section 100 within a predetermined range. Specifically, the opening relief valve V14a and the closing relief valve V14b function as protection valves in the event of an abnormal rise in pressure. Furthermore, the opening pilot check valve V13a and the closing pilot check valve V13b function as valves for independently controlling the opening and closing hydraulic pressures.

[0097] [D] Details of the detection unit 800 and the control unit 900 The detection unit 800 and the control unit 900 that constitute the hybrid servo system of this embodiment will be described in detail below.

[0098] FIG. 4 is a functional block diagram showing a detector 800 and a controller 900 in the hybrid servo system of the embodiment.

[0099] [D-1] Details of the detection unit 800 As shown in FIG. 4, the detection unit 800 has a first abnormality detection unit 821, a second abnormality detection unit 831, a third abnormality detection unit 832, a fourth abnormality detection unit 841, and a guide vane no-load opening detection unit 842.

[0100] The first abnormality detection unit 821 outputs a first detection signal S821 as the detection signal S800 when it detects that the deviation between the actual measurement value and the set value for the rotation speed of the generator 98 is larger than a predetermined threshold. The first detection signal S821 is output, for example, when the deviation in the rotation speed of the generator 98 exceeds a threshold at which it is determined that there is a possibility that an abnormality has occurred in one of the water turbines 90 during execution of a speed governing control operation. The first abnormality detection unit 821 outputs the first detection signal S821 in accordance with the result of measurement of the rotation speed of the generator 98 by a rotation speed measuring device (not shown).

[0101] The second abnormality detection unit 831 outputs a second detection signal S831 as the detection signal S800 when a failure detector (not shown) detects a failure in a part of the generator 98 that constitutes the water turbine 90 and that affects the power grid 700, or a failure in an electrical device for transmitting power generated by the generator 98 to the power grid 700. The second abnormality detection unit 831 includes a relay (not shown) that outputs the second detection signal S831 in accordance with the detection result of the above-mentioned failure. The second detection signal S831 is output, for example, when an excitation device that constitutes the generator 98 fails, or when a device for transforming or transmitting power fails.

[0102] The third abnormality detection unit 832 outputs a third detection signal S832 as the detection signal S800 when a mechanical failure is detected by a failure detector (not shown) in the water turbine 90. The third abnormality detection unit 832 includes a relay (not shown) that outputs the third detection signal S832 in accordance with the detection result of the failure.

[0103] The fourth abnormality detection unit 841 outputs a fourth detection signal S841 as the detection signal S800 when a fault in a part of the generator 98 constituting the water turbine 90 that does not affect the power grid 700 is detected by a fault detector (not shown). The fourth abnormality detection unit 841 includes a relay (a sudden load no-excitation protection relay; not shown) that outputs the fourth detection signal S841 in accordance with the detection result of the fault. The fourth detection signal S841 is output, for example, when a fault occurs in a generator control panel (not shown) that controls the operation of the generator 98.

[0104] Guide vane no-load opening detection unit 842 outputs a fifth detection signal S842 as detection signal S800 when the opening detector (displacement detection unit 500) detects that the opening of guide vane 95 is greater than the no-load opening. Guide vane no-load opening detection unit 842 includes a relay (not shown) that outputs the fifth detection signal S842 when the opening of guide vane 95 is greater than the no-load opening.

[0105] [D-2] Details of the control unit 900 When the control unit 900 is to perform a sudden closing operation of the guide vane 95 while power is being output normally from the generator 98, it outputs a sudden closing operation command S900 to the hydraulic circuit unit 100, as shown in FIG. 4.

[0106] Here, when the power output from the generator 98 to the power system 700 is not zero, the opening of the guide vane 95 is greater than the no-load opening, the circuit breaker (not shown) is not disconnecting the generator 98 from the power system 700 (parallel state), or the frequency of the power output from the generator 98 is a preset normal value, the control unit 900 determines that power is being output normally from the generator 98.

[0107] Furthermore, when it is determined that an abnormality has occurred in the water turbine 90 or the power system 700 based on the detection signal S800 input from the detection unit 800, the control unit 900 outputs a sudden closing operation command S900.

[0108] As shown in FIG. 4, the control unit 900 includes an OR operation unit 912, an AND operation unit 913, and an OR operation unit 921.

[0109] In the control unit 900, the OR operation unit 912 outputs an operation output signal S912 when the second detection signal S831 is output from the second abnormality detection unit 831 or when the third detection signal S832 is output from the third abnormality detection unit 832.

[0110] In the control unit 900, the AND calculation unit 913 is configured to output a calculation output signal S913 when the fourth abnormality detection unit 841 outputs a fourth detection signal S841 and the guide vane no-load opening detection unit 842 outputs a fifth detection signal S842.

[0111] In the control unit 900, when a first detection signal S821 is output from the first abnormality detection unit 821, when a calculation output signal S912 is output from the OR calculation unit 912, or when a calculation output signal S913 is output from the AND calculation unit 913, the OR calculation unit 921 outputs a sudden closing operation command S900 to the hydraulic circuit unit 100. When the sudden closing operation command S900 is output to the hydraulic circuit unit 100, the sudden closing operation is executed.

[0112] In this embodiment, the sudden closing operation is partially different depending on the type of detection signal S800 input from the detection unit 800 to the control unit 900.

[0113] (Case 3-1) Specifically, when a sudden closing operation is performed in response to a first detection signal S821 being input from the first abnormality detection unit 821 to the control unit 900, the power generating operation of the water turbine 90 is stopped so that the power output from the generator 98 to the power system 700 instantly becomes zero (for example, the rated power instantly changes from 100 kW to 0 kW), and the state between the generator 98 and the power system 700 is instantly shifted from a parallel state to a disconnected state (see FIG. 1). In other words, in this case, the hydraulic oil stored in the accumulator 140 is supplied to the second hydraulic chamber C52b of the cylinder 52 via the stored oil supply solenoid valve V35 and the like until the opening of the guide vane 95 reaches the fully closed state.

[0114] (Case 3-2) When the second detection signal S831 is input from the second abnormality detection unit 831 to the control unit 900 to execute a quick-closing operation (see FIG. 4), the power generating operation of the water turbine 90 is stopped so that the power output from the generator 98 to the power system 700 instantly becomes zero (for example, the rated power instantly changes from 100 kW to 0 kW), and the state between the generator 98 and the power system 700 is instantly shifted from a parallel state to a disconnected state (see FIG. 1). In other words, in this case, the hydraulic oil stored in the accumulator 140 is supplied to the second hydraulic chamber C52b of the cylinder 52 via the stored oil supply solenoid valve V35 and the like until the opening of the guide vane 95 reaches the fully closed state.

[0115] (Case 3-3) When the third detection signal S832 is input from the third abnormality detection unit 832 to the control unit 900 to execute a quick-closing operation (see FIG. 4), the power generating operation of the water turbine 90 is stopped so that the power output from the generator 98 to the power grid 700 is gradually reduced to zero (for example, gradually progressing from 100 kW, 90 kW, 10 kW, to 0 kW), and the state between the generator 98 and the power grid 700 is shifted from a parallel state to a disconnected state (see FIG. 1). That is, in this case, the supply and stop of hydraulic oil from the accumulator 140 to the second hydraulic chamber C52b of the cylinder 52 via the stored-pressure oil supply solenoid valve V35 and the like is alternately repeated so that the opening of the guide vane 95 is gradually reduced to a fully closed state.

[0116] (Case 3-4) When the fourth detection signal S841 is input from the fourth abnormality detection unit 841 to the control unit 900 to execute a quick closing operation (see FIG. 4), the power generating operation of the water turbine 90 is continued with the opening of the guide vane 95 set to the no-load opening. That is, in this case, the hydraulic oil stored in the accumulator 140 is supplied to the second hydraulic chamber C52b of the cylinder 52 via the stored oil supply solenoid valve V35 and the like until the opening of the guide vane 95 reaches the no-load opening (see FIG. 1).

[0117] [E] Summary As described above, in the hybrid servo system of this embodiment, the hydraulic circuit section 100 is configured to drive the hydraulic servo motor 50 for performing closing and opening operations on the guide vanes 95. The hydraulic servo motor 50 has a cylinder 52 in which the piston 55 provided on the operating rod 51 for operating the guide vanes 95 is housed in the internal space C52, and the internal space C52 is divided by the piston 55 into a first hydraulic chamber C52a and a second hydraulic chamber C52b.

[0118] The hydraulic circuit section 100 of this embodiment has a two-way pump 110, an accumulator 140, an accumulated oil supply pilot check valve V33, and an accumulated oil supply solenoid valve V35.

[0119] When performing an opening operation, the two-way pump 110 supplies hydraulic oil to the first hydraulic chamber C52a via the opening pilot valve V30a, and when performing a closing operation, the two-way pump 110 supplies hydraulic oil to the second hydraulic chamber C52b via the closing pilot valve V30b.

[0120] When the guide vane 95 is to be quickly closed, the accumulator oil supply solenoid valve V35 operates to supply hydraulic oil stored in the accumulator 140 to the pilot port of the accumulator oil supply pilot check valve V33, the pilot port of the opening pilot valve V30a, and the pilot port of the closing pilot valve V30b. As a result, the hydraulic oil stored in the accumulator 140 is supplied to the second hydraulic chamber C52b via the accumulator oil supply pilot check valve V33 and the closing pilot valve V30b, and hydraulic oil is discharged from the first hydraulic chamber C52a to the oil collection tank 130 via the opening pilot valve V30a. The quick-closing operation is performed by controlling the operation of the accumulator oil supply solenoid valve V35 when an abnormality occurs in the hydraulic turbine 90 or in the power system 700 while the generator 98 is outputting power normally.

[0121] In the hybrid servo system of this embodiment, the operation of the water turbine 90 is stopped regardless of the rotation speed of the water turbine 90, and therefore the accumulator 140 can be operated under predetermined conditions without being affected by the operating state of the water turbine 90, so there is no need to excessively increase the amount of hydraulic oil consumed depending on the operating state, and the amount of hydraulic oil consumed can be reduced. Therefore, in this embodiment, there is no need to increase the capacity of the accumulator 140, and therefore the hybrid servo system can be easily made smaller.

[0122] In this embodiment, the sudden closing operation is performed by switching the stored-oil supply solenoid valve V35 from an energized state to a de-energized state.

[0123] Furthermore, in this embodiment, the closing operation and the opening operation are not performed by supplying hydraulic oil from the accumulator 140 to the hydraulic servo motor 50, but by supplying hydraulic oil from the bidirectional pump 110 to the hydraulic servo motor 50. Therefore, in this embodiment, even after the state between the generator 98 and the power grid 700 has shifted from a parallel state to a parallel-off state, the speed governing control operation of the water turbine 90 can be performed according to the situation by using the bidirectional pump 110.

[0124] <Other> Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0125] 50: Hydraulic servo motor, 51: Operating rod, 52: Cylinder, 55: Piston, 90: Water turbine, 91: Runner, 91a: Runner crown, 91b: Runner band, 91c: Runner blade, 92: Main shaft, 93: Upper cover, 94: Lower cover, 95: Guide vane, 96: Casing, 97: Discharge pipe, 98: Generator, 100: Hydraulic circuit section, 110: Bidirectional pump, 130: Oil collection tank, 140: Accumulator, 500: Displacement detection section, 700: Power system, 800: Detection section, 821: First abnormality detection section, 831: Second abnormality detection section, 832: Third abnormality detection section, 841: Fourth abnormality detection section, 842 : Guide vane no-load opening detection unit, 900: Control unit, 912: OR calculation unit, 913: AND calculation unit, 921: OR calculation unit, C52: Internal space, C52a: First hydraulic chamber, C52b: Second hydraulic chamber, DG: De-energized state, EG: Energized state, SV32: Gate valve, V13a: Open-side pilot check valve, V13b: Close-side pilot check valve, V14a: Open-side relief valve, V14b: Close-side relief valve, V30a: Open-side pilot valve, V30b: Close-side pilot valve, V33: Accumulator oil supply pilot check valve, V35: Accumulator oil supply solenoid valve, V36a: Open-side check valve, V36b: Close-side check valve

Claims

1. A hybrid servo system that controls the operation of a water turbine that includes a runner that rotates when water is supplied through guide vanes, and a generator that generates electricity through the rotation of the runner, and outputs electric power from the generator to an electric power grid, a hydraulic circuit unit that drives a hydraulic servo motor for performing a closing operation and an opening operation of the guide vane; a control unit for controlling the operation of the hydraulic circuit unit; Preparation, The hydraulic servo motor a cylinder having an internal space in which a piston provided on an operating rod for operating the guide vane is accommodated, the internal space being divided into a first hydraulic chamber and a second hydraulic chamber by the piston; and The hydraulic circuit section includes: a two-way pump configured to supply hydraulic oil to the first hydraulic chamber via an opening-side pilot valve when performing the opening operation, and to supply hydraulic oil to the second hydraulic chamber via a closing-side pilot valve when performing the closing operation; an accumulator configured to store hydraulic fluid; an accumulated oil supply pilot check valve installed in an oil passage through which hydraulic oil flows from the accumulator to the closing-side pilot valve; an accumulator oil supply solenoid valve configured to supply hydraulic oil stored in the accumulator to a pilot port of the accumulator oil supply pilot check valve, a pilot port of the opening-side pilot valve, and a pilot port of the closing-side pilot valve, respectively, when a quick-closing operation of the guide vane is performed; and when the sudden closing operation is performed, the hydraulic oil stored in the accumulator is supplied to the second hydraulic chamber via the stored oil supply pilot check valve and the closing-side pilot valve, and the hydraulic oil is discharged from the first hydraulic chamber to an oil collection tank via the opening-side pilot valve, When an abnormality occurs in the hydraulic turbine or in the power system while power is being normally output from the generator, the control unit controls the operation of the stored oil supply solenoid valve to perform the sudden closing operation. Hybrid servo system.

2. The sudden closing operation is performed by switching the pressure-accumulated oil supply solenoid valve from an excited state to a de-energized state. The hybrid servo system of claim 1 .

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