A hydraulic load grading control system and method for an indirect wave energy device

Abstract

The present invention discloses a hydraulic load grading control system and method for an indirect wave energy device. The system includes a first hydraulic cylinder group, a second hydraulic cylinder group, a third hydraulic cylinder group, a high-pressure accumulator group, a pressure detection control module, a first hydraulic generator group, a second hydraulic generator group, and a third hydraulic generator group. The detection end of the pressure detection control module is used to obtain the internal pressure of the high-pressure accumulator group, compare the internal pressure with a preset pressure level, and control the opening and closing of the reversing valve and the solenoid valve based on the comparison result. The beneficial effect of the present invention is that it can automatically load all hydraulic loads or automatically unload all hydraulic loads, allowing the wave energy device to operate at full load or at optimal energy conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic power generation control for wave energy devices, and in particular to a hydraulic load grading control system and method for an indirect wave energy device. Background Art

[0002] The conversion process of a conventional hydraulic wave energy device is as follows: driven by waves, the wave-absorbing float drives the hydraulic cylinder installed with it to reciprocate. During this reciprocating motion, the hydraulic cylinder pumps hydraulic oil into the high-pressure accumulator group, converting wave energy into hydraulic energy. This is called primary energy conversion. When the pressure of the accumulator group reaches the set pressure, the control valve group is activated, releasing the high-pressure hydraulic oil in the accumulator group to impact the hydraulic motor, causing it to rotate and converting hydraulic energy into rotational mechanical energy. This is called secondary energy conversion. The hydraulic motor drives the generator connected to the same axis to rotate and generate electricity, converting the rotational mechanical energy into electrical energy. This is called tertiary energy conversion.

[0003] The primary energy conversion process of a wave energy device is a mechanical vibration process. Within this process, an optimal wave capture efficiency exists for each wave force. This efficiency corresponds to an optimal hydraulic load, or the damping force of the hydraulic cylinder, which is calculated by multiplying the effective working area of the hydraulic cylinder by the accumulator pressure. Given a set accumulator pressure, the primary energy conversion efficiency is optimized by adjusting the effective working area of the hydraulic cylinder, or in other words, the amount of hydraulic load applied to the cylinder. Therefore, how to automatically select the appropriate hydraulic load based on wave size—that is, the number of hydraulic cylinders actively working—becomes a key factor in improving the power generation efficiency of wave energy devices. Active hydraulic cylinders are those whose outlets are connected to the high-pressure accumulator bank. Inactive hydraulic cylinders are those whose outlets are connected to the low-pressure circuit and do not participate in any work.

[0004] Currently, most wave energy devices adjust the size of the hydraulic load mainly by manual adjustment, which is done by manually judging the wave size and then controlling the direction of the hydraulic cylinder's oil outlet. There are few reports on control technologies that allow wave energy devices to autonomously adjust the size of the hydraulic load according to the wave size. In view of this, the applicant previously applied for an invention patent "A Hydraulic Automatic Gradual Loading Controller for Wave Energy Devices" (application number CN201610614272.X). The controller requires the addition of multiple hydraulic devices to measure wave power. The measurement system is independent of the energy conversion system, and the control accuracy of the controller is related to the flow control valve. In actual operation, it is difficult for the flow control valve to accurately adjust the flow. Even slight vibrations will cause the flow-pressure characteristic curve of the flow control valve to change. Therefore, the actual application of this system is not ideal. Summary of the Invention

[0005] In response to the above problems, the present invention proposes a hydraulic load grading control system and method for an indirect wave energy device, which indirectly and automatically measures the size of the waves through its own energy conversion system and autonomously selects the size of the hydraulic load according to the size of the waves, thereby improving the primary energy conversion efficiency of the wave energy device and having strong operability.

[0006] To solve the above technical problems, the first aspect of the present invention provides a hydraulic load grading control system for an indirect wave energy device, comprising a first hydraulic cylinder group, a second hydraulic cylinder group, a third hydraulic cylinder group, a high-pressure accumulator group, a pressure detection control module, a first hydraulic generator group, a second hydraulic generator group, and a third hydraulic generator group; the output end of the first hydraulic cylinder group is directly connected to the input end of the high-pressure accumulator group, the output ends of the second hydraulic cylinder group and the third hydraulic cylinder group are respectively connected to the input end of the high-pressure accumulator group and the return oil tank through independent reversing valves, and the output end of the high-pressure accumulator group is respectively connected to the first hydraulic generator group, the second hydraulic generator group, and the third hydraulic generator group through independent solenoid valves. The detection end of the pressure detection control module is used to obtain the internal pressure of the high-pressure accumulator group and compare the internal pressure with a preset pressure level. According to the comparison result, the reversing valve and the solenoid valve are respectively controlled to be on and off. The reversing valve is used to control the second hydraulic cylinder group and the third hydraulic cylinder group to enter / exit the effective working state, and the solenoid valve is used to control the first hydraulic generator group, the second hydraulic generator group, and the third hydraulic generator group to enter / exit the power generation state.

[0007] A second aspect of the present invention provides a hydraulic load grading control method for an indirect wave energy device, which is used in the above-mentioned hydraulic load grading control system for an indirect wave energy device, and is characterized by comprising: obtaining the internal pressure P of the high-pressure accumulator group in real time, setting gradually increasing pressure values P1, P2, P3, P4, P5 and P6, and gradually increasing pressure values P21, P22, P31 and P32, wherein the following pressure relationship P1 needs to be satisfied: <P21<P3<P31<P5,P2<P22<P4<P32<P6;

[0008] The control method includes a first mode, a second mode, a third mode, a fourth mode and a fifth mode, and each mode can only be transformed into an adjacent mode at a time;

[0009] In the first mode, if P2≤P<P22, the second hydraulic cylinder group and the third hydraulic cylinder group are triggered to connect to the return oil tank through the corresponding reversing valve, connect the solenoid valve corresponding to the first hydraulic generator group, and disconnect the solenoid valve corresponding to the second hydraulic generator group and the third hydraulic generator group. After P2≤P<P22 is triggered, the solenoid valve corresponding to the first hydraulic generator group is allowed to be disconnected only under the condition of P≤P1;

[0010] In the second mode, if P22 ≤ P < P4, the second hydraulic cylinder group is triggered to connect to the input end of the high-pressure accumulator group through the corresponding reversing valve, the third hydraulic cylinder group is connected to the return oil tank through the corresponding reversing valve, the solenoid valve corresponding to the first hydraulic generator group is connected, and the solenoid valves corresponding to the second and third hydraulic generator groups are disconnected. After P22 ≤ P < P4 is triggered, the second hydraulic cylinder group is allowed to be controlled to connect to the return oil tank through the corresponding reversing valve only under the condition of P ≤ P21;

[0011] In the third mode, if P4 ≤ P < P32, the second hydraulic cylinder group is triggered to connect to the input end of the high-pressure accumulator group through the corresponding reversing valve, and the third hydraulic cylinder group is connected to the return oil tank through the corresponding reversing valve, connecting the solenoid valves corresponding to the first hydraulic generator group and the second hydraulic generator group, and disconnecting the solenoid valve corresponding to the third hydraulic generator group. After P4 ≤ P < P32 is triggered, the solenoid valve corresponding to the second hydraulic generator group is allowed to be disconnected only under the condition of P ≤ P3;

[0012] In the fourth mode, if P32 ≤ P < P6, the second and third hydraulic cylinder groups are triggered to connect to the input end of the high-pressure accumulator group through the corresponding reversing valves, the solenoid valves corresponding to the first and second hydraulic generator groups are connected, and the solenoid valve corresponding to the third hydraulic generator group is disconnected. After P32 ≤ P < P6 is triggered, the third hydraulic cylinder group is allowed to be controlled to connect to the return oil tank through the corresponding reversing valve only under the condition of P ≤ P31;

[0013] In the fifth mode, if P≥P6, the reversing valves corresponding to the second hydraulic cylinder group and the third hydraulic cylinder group are triggered to be connected to the input end of the high-pressure accumulator group, and the solenoid valves corresponding to the first hydraulic generator group, the second hydraulic generator group and the third hydraulic generator group are connected. After P≥P6 is triggered, the solenoid valve corresponding to the third hydraulic generator group is allowed to be disconnected only under the condition of P≤P5.

[0014] The beneficial effects of the present invention are as follows: during the instantaneous change of wave impact, the entire hydraulic load can be automatically loaded or automatically unloaded, so that the wave energy device can operate in a full-load state or in a state with optimal energy conversion efficiency, and the movement amplitude of the wave-absorbing float can be reduced, thereby reducing the probability of collision between the wave-absorbing float and the device base, thereby protecting the wave energy device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic structural diagram of a hydraulic load classification control system for an indirect wave energy device disclosed in the first embodiment of the present invention;

[0016] Figure 2 This is a schematic structural diagram of a hydraulic load classification control system for an indirect wave energy device disclosed in the second embodiment of the present invention;

[0017] Figure 3 This is the control logic diagram of the hysteresis comparator controller;

[0018] Figure 4 A schematic diagram of the operation of the hydraulic load classification control system of the indirect wave energy device disclosed in the second embodiment of the present invention under low wave conditions;

[0019] Figure 5 A schematic diagram of the operation of the hydraulic load classification control system of the indirect wave energy device disclosed in the second embodiment of the present invention under the transition from small wave conditions to medium wave conditions;

[0020] Figure 6 A schematic diagram of the operation of the hydraulic load classification control system of the indirect wave energy device disclosed in the second embodiment of the present invention when the wave condition changes from medium to large wave conditions;

[0021] Figure 7 A schematic diagram of the operation of the hydraulic load classification control system of the indirect wave energy device disclosed in the second embodiment of the present invention under relatively large wave conditions;

[0022] Among them: 1-first hydraulic cylinder group, 2-second hydraulic cylinder group, 3-third hydraulic cylinder group, 4-high-pressure accumulator group, 5-pressure detection control module, 6-first hydraulic generator group, 7-second hydraulic generator group, 8-third hydraulic generator group, 101-first hydraulic cylinder, 102-first one-way valve, 103-second one-way valve, 201-second hydraulic cylinder, 202-third one-way valve, 203-fourth one-way valve, 204-first two-position three-way reversing valve, 301-third hydraulic cylinder, 302-fifth one-way valve, 303-sixth one-way valve, 3 04-Second two-position three-way reversing valve, 501-Pressure sensor, 502-First hysteresis comparator, 503-Second hysteresis comparator, 504-Third hysteresis comparator, 505-Fourth hysteresis comparator, 506-Fifth hysteresis comparator, 601-First two-position two-way solenoid valve, 602-First hydraulic motor, 603-First generator, 701-Second two-position two-way solenoid valve, 702-Second hydraulic motor, 703-Second generator, 801-Third two-position two-way solenoid valve, 802-Third hydraulic motor, 803-Third generator. DETAILED DESCRIPTION

[0023] To make the objectives, technical solutions, and advantages of the present invention more clear and distinct, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all of the present invention.

[0024] Example 1

[0025] This embodiment proposes a hydraulic load classification control system for an indirect wave energy device. This embodiment takes a three-level load, i.e., three hydraulic cylinders for load adjustment as an example. Figure 1 As shown, it includes a first hydraulic cylinder group 1, a second hydraulic cylinder group 2, a third hydraulic cylinder group 3, a high-pressure accumulator group 4, a pressure detection control module 5, a first hydraulic generator group 6, a second hydraulic generator group 7 and a third hydraulic generator group 8;

[0026] The output end of the first hydraulic cylinder group 1 is directly connected to the input end of the high-pressure accumulator group 4, and the output ends of the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 are respectively connected to the input end of the high-pressure accumulator group 4 and the return oil tank through independent reversing valves. The output end of the high-pressure accumulator group 4 is respectively connected to the first hydraulic generator group 6, the second hydraulic generator group 7 and the third hydraulic generator group 8 through independent solenoid valves. The detection end of the pressure detection control module 5 is used to obtain the internal pressure of the high-pressure accumulator group 4 and compare the internal pressure with a preset pressure level. According to the comparison result, the reversing valve and the solenoid valve are controlled to be on and off respectively. The reversing valve is used to control the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 to enter / exit the effective working state, and the solenoid valve is used to control the first hydraulic generator group 6, the second hydraulic generator group 7 and the third hydraulic generator group 8 to enter / exit the power generation state.

[0027] In this embodiment, no major changes are made to the original hydraulic energy conversion system. Only a reversing valve and a pressure detection control module 5 are added. The logical control strategy is simple and easy to implement. During the design process, the generator power and the hydraulic motor displacement can be calculated according to the incoming wave conditions, and appropriate start and close pressures can be set for the pressure detection control module 5. This enables the wave energy device's hydraulic load level to indirectly and automatically measure the size of the wave, and autonomously adjust the size of the hydraulic load according to the size of the wave, thereby improving the primary energy conversion efficiency of the wave energy device.

[0028] Example 2

[0029] This embodiment provides another hydraulic load classification control system for an indirect wave energy device. Based on the first embodiment, the connection relationship between the first hydraulic cylinder group 1, the second hydraulic cylinder group 2, the third hydraulic cylinder group 3, the high-pressure accumulator group 4, the pressure detection control module 5, the first hydraulic generator group 6, the second hydraulic generator group 7 and the third hydraulic generator group 8 is further described below.

[0030] like Figure 2As shown, the first hydraulic cylinder group 1 includes a first hydraulic cylinder 101, the input end of the first hydraulic cylinder 101 is connected to the oil return tank through a first one-way valve 102, and the output end of the first hydraulic cylinder 101 is connected to the output end of the high-pressure accumulator group 4 through a second one-way valve 103. The second hydraulic cylinder group 2 includes a second hydraulic cylinder 201, the input end of the second hydraulic cylinder 201 is connected to the oil return tank through a third one-way valve 202, and the output end of the second hydraulic cylinder 201 is connected to the A end of the first two-position three-way reversing valve 204 through a fourth one-way valve 203. The B end of the valve 204 is connected to the return oil tank, the C end of the first two-position three-way reversing valve 204 is connected to the input end of the high-pressure accumulator group 4, the third hydraulic cylinder group 3 includes a third hydraulic cylinder 301, the input end of the third hydraulic cylinder 301 is connected to the return oil tank through the fifth one-way valve 302, the output end of the third hydraulic cylinder 301 is connected to the D end of the second two-position three-way reversing valve 304 through the sixth one-way valve 303, the E end of the second two-position three-way reversing valve 304 is connected to the return oil tank, and the F end of the second two-position three-way reversing valve 304 is connected to the input end of the high-pressure accumulator group 4.

[0031] The first hydraulic generator group 6 includes a first two-position two-way solenoid valve 601, the G end of the first two-position two-way solenoid valve 601 is connected to the output end of the high-pressure accumulator group 4, the H end of the first two-position two-way solenoid valve 601 is connected to the input end of the first hydraulic motor 602, the controlled end of the first two-position two-way solenoid valve 601 is connected to the control end of the pressure detection control module 5, the output end of the first hydraulic motor 602 is connected to the return oil tank, and the output shaft of the first hydraulic motor 602 is connected to the input shaft of the first generator 603.

[0032] The second hydraulic generator set 7 includes a second two-position two-way solenoid valve 701, the I end of the second two-position two-way solenoid valve 701 is connected to the output end of the high-pressure accumulator group 4, the J end of the second two-position two-way solenoid valve 701 is connected to the input end of the second hydraulic motor 702, the controlled end of the second two-position two-way solenoid valve 701 is connected to the control end of the pressure detection control module 5, the output end of the second hydraulic motor 702 is connected to the return oil tank, and the output shaft of the second hydraulic motor 702 is connected to the input shaft of the second generator 703.

[0033] The third hydraulic generator group 8 includes a third two-position two-way solenoid valve 801, the K end of the third two-position two-way solenoid valve 801 is connected to the output end of the high-pressure accumulator group 4, the L end of the third two-position two-way solenoid valve 801 is connected to the input end of the third hydraulic motor 802, the controlled end of the third two-position two-way solenoid valve 801 is connected to the control end of the pressure detection control module 5, the output end of the third hydraulic motor 802 is connected to the return oil tank, and the output shaft of the third hydraulic motor 802 is connected to the input shaft of the third generator 803.

[0034] The pressure detection control module 5 includes a pressure sensor 501, the detection end of the pressure sensor 501 is installed at the output end of the high-pressure accumulator group 4, the control end of the pressure sensor 501 is respectively connected to the input ends of the first hysteresis comparator 502, the second hysteresis comparator 503, the third hysteresis comparator 504, the fourth hysteresis comparator 505 and the fifth hysteresis comparator 506, and the output ends of the first hysteresis comparator 502, the second hysteresis comparator 503, the third hysteresis comparator 504, the fourth hysteresis comparator 505 and the fifth hysteresis comparator 506 are respectively connected to the controlled ends of the first two-position two-way solenoid valve 601, the first two-position three-way reversing valve 204, the second two-position three-way reversing valve 304, the third two-position two-way solenoid valve 801 and the second two-position two-way solenoid valve 701.

[0035] Specifically, the control logic diagram of the hysteresis comparator controller is as follows: Figure 3 The control logic diagram of the hysteresis comparator controller receives the pressure signal from the pressure sensor. Initially, it is in state 0, with no voltage signal output. When the pressure gradually rises to po, it outputs a voltage signal, indicating state 1. If the pressure continues to rise, state 1 will persist. When the pressure drops but does not reach pc, state 1 remains. When the pressure drops to pc, the voltage signal output stops, reaching state 0, and the next cycle begins.

[0036] Example 3

[0037] This embodiment provides a hydraulic load grading control method for an indirect wave energy device, which is used in the hydraulic load grading control system of the indirect wave energy device described in the first embodiment, and is characterized by comprising: obtaining the internal pressure P of the high-pressure accumulator group 4 in real time, setting gradually increasing pressure values P1, P2, P3, P4, P5 and P6, and gradually increasing pressure values P21, P22, P31 and P32, wherein the following pressure relationship P1 needs to be satisfied: <P21<P3<P31<P5,P2<P22<P4<P32<P6。

[0038] The control method includes a first mode, a second mode, a third mode, a fourth mode and a fifth mode, and each mode can only be transformed into an adjacent mode at a time;

[0039] In the first mode, if P2≤P<P22, the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 are triggered to connect to the return oil tank through the corresponding reversing valves, the solenoid valve corresponding to the first hydraulic generator group 6 is connected, and the solenoid valves corresponding to the second hydraulic generator group 7 and the third hydraulic generator group 8 are disconnected. After P2≤P<P22 is triggered, the solenoid valve corresponding to the first hydraulic generator group 6 is allowed to be disconnected only when P≤P1 is required;

[0040] In the second mode, if P22 ≤ P < P4, the second hydraulic cylinder group 2 is triggered to connect to the input end of the high-pressure accumulator group 4 through the corresponding reversing valve, the third hydraulic cylinder group 3 is connected to the return oil tank through the corresponding reversing valve, the solenoid valve corresponding to the first hydraulic generator group 6 is connected, and the solenoid valves corresponding to the second hydraulic generator group 7 and the third hydraulic generator group 8 are disconnected. After P22 ≤ P < P4 is triggered, the second hydraulic cylinder group 2 is allowed to be controlled to connect to the return oil tank through the corresponding reversing valve only under the condition of P ≤ P21;

[0041] In the third mode, if P4≤P<P32, the second hydraulic cylinder group 2 is triggered to connect to the input end of the high-pressure accumulator group 4 through the corresponding reversing valve, and the third hydraulic cylinder group 3 is connected to the return oil tank through the corresponding reversing valve. The solenoid valves corresponding to the first hydraulic generator group 6 and the second hydraulic generator group 7 are connected, and the solenoid valve corresponding to the third hydraulic generator group 8 is disconnected. After P4≤P<P32 is triggered, the solenoid valve corresponding to the second hydraulic generator group 7 is allowed to be disconnected only under the condition of P≤P3;

[0042] In the fourth mode, if P32≤P<P6, the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 are triggered to connect to the input end of the high-pressure accumulator group 4 through the corresponding reversing valves, the solenoid valves corresponding to the first hydraulic generator group 6 and the second hydraulic generator group 7 are connected, and the solenoid valve corresponding to the third hydraulic generator group 8 is disconnected. After P32≤P<P6 is triggered, the third hydraulic cylinder group 3 is allowed to be controlled to connect to the return oil tank through the corresponding reversing valve only when P≤P31 is required;

[0043] In the fifth mode, if P≥P6, the reversing valves corresponding to the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 are triggered to be connected to the input end of the high-pressure accumulator group 4, and the solenoid valves corresponding to the first hydraulic generator group 6, the second hydraulic generator group 7 and the third hydraulic generator group 8 are connected. After P≥P6 is triggered, the solenoid valve corresponding to the third hydraulic generator group 8 is allowed to be disconnected only under the condition of P≤P5.

[0044] In this embodiment, the wave size is indirectly measured by measuring the internal pressure P of the accumulator group 4. The hydraulic load is then automatically adjusted based on the wave size, thereby improving the primary energy conversion efficiency of the wave energy device. Furthermore, the adjustment process does not require frequent opening and closing of valves.

[0045] In this embodiment, during the instantaneous change of wave impact, the entire hydraulic load can be automatically loaded or automatically unloaded, so that the wave energy device operates in a full-load state or in a state of optimal energy conversion efficiency. The movement amplitude of the wave-absorbing float can be reduced, thereby reducing the probability of collision between the wave-absorbing float and the device base, thereby protecting the wave energy device.

[0046] In addition, the method described in this embodiment can be extended to control the addition and subtraction of more hydraulic cylinders, dividing the hydraulic load into more levels, so as to adapt to the wave conditions in various oceans.

[0047] Embodiment 4

[0048] This embodiment provides another indirect wave energy device hydraulic load grading control method for the indirect wave energy device hydraulic load grading control system described in Embodiment 2, including: obtaining the internal pressure P of the high-pressure accumulator group 4 in real time through the pressure sensor 501, setting gradually increasing pressure values P1, P2, P3, P4, P5, and P6, and gradually increasing pressure values P21, P22, P31, and P32. Among them, the following pressure relationships need to be satisfied: P1 < P21 < P3 < P31 < P5, P2 < P22 < P4 < P32 < P6; P1 and P2 are respectively the lower threshold and upper threshold of the first hysteresis comparator 502, P21 and P22 are respectively the lower threshold and upper threshold of the second hysteresis comparator 503, P31 and P32 are respectively the lower threshold and upper threshold of the third hysteresis comparator 504, P5 and P6 are respectively the lower threshold and upper threshold of the fourth hysteresis comparator 505, and P3 and P4 are respectively the lower threshold and upper threshold of the fifth hysteresis comparator 506;

[0049] The control method includes a first mode, a second mode, a third mode, a fourth mode, and a fifth mode, and each mode can only transform to an adjacent mode each time;

[0050] In the first mode, if P2 ≤ P < P22, trigger the first hysteresis comparator 502 to control the G end and H end of the first two-position two-way solenoid valve 601 to be connected. After P2 ≤ P < P22 is triggered, only when P ≤ P1 is satisfied, the first hysteresis comparator 502 is allowed to disconnect the connection between the G end and H end of the first two-position two-way solenoid valve 601;

[0051] In the second mode, if P22 ≤ P < P4, trigger the second hysteresis comparator 503 to control the A end and C end of the first two-position three-way directional control valve 204 to be connected. After P22 ≤ P < P4 is triggered, only when P ≤ P21 is satisfied, the second hysteresis comparator 503 is allowed to disconnect the connection between the A end and C end of the first two-position three-way directional control valve 204;

[0052] In the third mode, if P4 ≤ P < P32, trigger the fifth hysteresis comparator 506 to control the I end and J end of the second two-position two-way solenoid valve 701 to be connected. After P4 ≤ P < P32 is triggered, only when P ≤ P3 is satisfied, the fifth hysteresis comparator 506 is allowed to disconnect the connection between the I end and J end of the second two-position two-way solenoid valve 701;

[0053] In the fourth mode, if P32 ≤ P < P6, the third hysteresis comparator 504 is triggered to connect the E and F terminals of the second 2-position 3-way reversing valve 304. After the triggering of P32 ≤ P < P6, the third hysteresis comparator 504 is allowed to disconnect the E and F terminals of the second 2-position 3-way reversing valve 304 only when P ≤ P31.

[0054] In the fifth mode, if P≥P6, the fourth hysteresis comparator 505 is triggered to control the connection between the K terminal and the L terminal of the third two-position two-way solenoid valve 801. After P≥P6 is triggered, the fourth hysteresis comparator 505 is allowed to disconnect the connection between the K terminal and the L terminal of the third two-position two-way solenoid valve 801 only under the condition of P≤P5.

[0055] After disconnecting the first two-position two-way solenoid valve 601, only the first hydraulic cylinder group 1 is operational in the system, and the system operates in initial mode. In initial mode, the oil outlet of the first hydraulic cylinder 101 is directly connected to the high-pressure accumulator group 4, performing normal energy storage and pressure stabilization, and is in a loading state with effective work. The oil outlets of the second hydraulic cylinder 201 and the third hydraulic cylinder 301 are connected to the A end of the first two-position three-way reversing valve 204 and the D end of the second two-position three-way reversing valve 304, respectively. The valve cores of the first two-position three-way reversing valve 204 and the second two-position three-way reversing valve 304 are both in the right position, with A and B connected and D and E connected. The oil outlets of the second hydraulic cylinder 201 and the third hydraulic cylinder 301 are connected back to the low-pressure oil circuit of the oil tank, and are in a follow-up state with ineffective work. At the same time, in full mode, the first hydraulic cylinder group 1 is always in operation, that is, uncontrolled.

[0056] Specifically, in the case of small waves, the first hydraulic cylinder 101 is in a loading state, and the second hydraulic cylinder group 2 and the third hydraulic cylinder group 3 are in a follow-up state. Driven by small waves, the stroke and speed of the movement of the first hydraulic cylinder 101 are relatively small, and the flow input from the first hydraulic cylinder 101 to the high-pressure accumulator group 4 is small. The pressure of the high-pressure accumulator group 4 gradually increases. The pressure signal is measured by the pressure sensor 501. When the pressure of the high-pressure accumulator group 4 rises to P2, the first hysteresis comparator 502 is initially in state 1, so a voltage signal is input to the first two-position two-way solenoid valve 601, causing the valve core to move to the left. The G end and the H end are in a connected state, and the high-pressure hydraulic cylinder in the high-pressure accumulator group 4 releases the impact to the first hydraulic motor 602 to drive the first generator 603 to work. Figure 4As shown. Because the flow rate of the first hydraulic cylinder 101 is less than the flow rate of the first hydraulic motor 602 during low waves, meaning the flow rate input to the high-pressure accumulator group 4 is less than the flow rate output, the pressure in the high-pressure accumulator group 4 immediately drops. When the pressure drops to P1, the first hysteresis comparator 502 returns to state 0, and no voltage signal is input to the first 2-position 2-way solenoid valve 601. The return spring returns the valve core to the right position, disconnecting the G and H terminals. The first hydraulic motor 602 and the first generator 603 stop operating, and the accumulator begins the next cycle of energy storage. Therefore, during low waves, the pressure in the high-pressure accumulator group 4 never exceeds P2, and only the first hydraulic cylinder 101 is loaded.

[0057] Specifically, when the waves gradually increase and enter the medium wave state, the stroke and speed of the first hydraulic cylinder 101 also increase accordingly, and the flow of the first hydraulic cylinder 101 input to the high-pressure accumulator group 4 increases. The flow of the first hydraulic cylinder 101 input to the accumulator is greater than the flow of the first hydraulic motor 602. The first hydraulic motor 602 will work continuously. At this time, although the first hydraulic motor 602 is always in the on state, the pressure of the high-pressure accumulator group 4 will continue to rise. When the pressure of the high-pressure accumulator group 4 rises to P22, the second hysteresis comparator 503 begins to be in state 1, so a voltage signal is input to the first two-position three-way reversing valve 204, causing the valve core to move to the left, and the A end and the C end are in a connected state, while the B end is disconnected. The oil outlet of the second hydraulic cylinder 201 will be connected to the high-pressure accumulator group 4 and is in an effective working loading state. At this point, the second hydraulic cylinder 201 has achieved autonomous loading, such as Figure 5 shown.

[0058] Specifically, at this time, both the first hydraulic cylinder 101 and the second hydraulic cylinder 201 are in the loading state. The sum of the flow rates of the first hydraulic cylinder 101 and the second hydraulic cylinder 201 flowing into the high-pressure accumulator group 4 is greater than the flow rate of the first hydraulic motor 602. The pressure of the high-pressure accumulator group 4 will continue to rise. When the pressure reaches P4, the fifth hysteresis comparator 506 starts to be in state 1. Therefore, a voltage signal is input to the second two-position two-way solenoid valve 701, causing the valve core to move leftward, and the I end and the J end are in a connected state. The high-pressure hydraulic cylinder in the high-pressure accumulator group 4 releases an impact to drive the second hydraulic motor 702 to drive the second generator 703 to work. In the medium wave condition, both the first hydraulic cylinder 101 and the second hydraulic cylinder 201 are in the effective work state. The sum of the flow rates of the two hydraulic cylinders input to the high-pressure accumulator group 4 is less than the sum of the flow rates of the first hydraulic motor 602 and the second hydraulic motor 702. Therefore, when the second hydraulic motor 702 is turned on, the pressure of the high-pressure accumulator group 4 will decrease. When it drops to P3, the fifth hysteresis comparator 506 returns to state 0, and no voltage signal is input to the second two-position two-way solenoid valve 701. Under the action of the return spring, the valve core returns to the right position, and the I end and the J end are in a disconnected state. The second hydraulic motor 702 and the second generator 703 stop working, and the pressure of the high-pressure accumulator group 4 starts to rise from P3 again. During this process, the pressure of the high-pressure accumulator group 4 will fluctuate within the range of P3 and P4, manifested as the first hydraulic motor 602 working continuously and the second hydraulic motor 702 working intermittently. Among them, the setting of the P22 value needs to meet the condition of P2 < P22 < P4.

[0059] Specifically, when the incoming wave continues to increase and is in a larger wave condition, the movement strokes and speeds of the first hydraulic cylinder 101 and the second hydraulic cylinder 201 increase correspondingly, and the flow rate input to the high-pressure accumulator group 4 also becomes correspondingly larger. The sum of the flow rates of the first hydraulic cylinder 101 and the second hydraulic cylinder 201 is greater than the sum of the flow rates of the first hydraulic motor 602 and the second hydraulic motor 702. Both the first hydraulic motor 602 and the second hydraulic motor 702 will work continuously. At this time, although both the first hydraulic motor 602 and the second hydraulic motor 702 are always in the on state, the pressure of the high-pressure accumulator group 4 will still continue to rise. When the pressure of the high-pressure accumulator group 4 rises to P32, the third hysteresis comparator 504 starts to be in state 1. Therefore, a voltage signal is input to the second two-position three-way directional control valve 304, causing the valve core to move leftward, and the D end and the F end are in a connected state, and the E end is disconnected. The oil outlet of the third hydraulic cylinder 301 will be connected to the high-pressure accumulator group and be in the loading state of effective work.至此,第三液压缸301也实现了自主加载,如 Figure 6 所示。

[0060] Specifically, when the first hydraulic cylinder 101, the second hydraulic cylinder 201, and the third hydraulic cylinder 301 are all in the loading state, the sum of the flow rates of the first hydraulic cylinder 101, the second hydraulic cylinder 201, and the third hydraulic cylinder 301 flowing into the high-pressure accumulator group 4 is greater than the sum of the flow rates of the first hydraulic motor 602 and the second hydraulic motor 702. The pressure of the high-pressure accumulator group 4 will continue to rise. When the pressure reaches P6, the fourth hysteresis comparator 505 starts to be in state 1. Therefore, a voltage signal is input to the third two-position two-way solenoid valve 801, causing the valve core to move to the left, and the K terminal and the L terminal are in a connected state. The high-pressure hydraulic cylinder of the high-pressure accumulator group 4 releases an impact, and the third hydraulic motor 802 drives the third generator 803 to work, as Figure 7 shown. In the case of relatively large waves, the first hydraulic cylinder 101, the second hydraulic cylinder 201, and the third hydraulic cylinder 301 are all in the effective working state. The sum of the flow rates of the first hydraulic cylinder 101, the second hydraulic cylinder 201, and the third hydraulic cylinder 301 input into the accumulator is less than the sum of the flow rates of the first hydraulic motor 602, the second hydraulic motor 702, and the third hydraulic motor 802. Therefore, when the third hydraulic motor 802 is started, the pressure of the high-pressure accumulator group 4 will decrease. When it drops to P5, the fourth hysteresis comparator 505 returns to state 0, and no voltage signal is input to the third two-position two-way solenoid valve 801. Under the action of the return spring, the valve core returns to the right position, and the K terminal and the L terminal are in a disconnected state. The third hydraulic motor 802 and the third generator 803 stop working, and the pressure of the high-pressure accumulator group 4 starts to rise from P5 again. During this process, the pressure of the high-pressure accumulator group 4 will fluctuate within the range of P5 and P6, manifested as the continuous operation of the first hydraulic motor 602 and the second hydraulic motor 702, and the intermittent operation of the third hydraulic motor 802. Among them, the setting of the P32 value needs to meet the condition of P4 < P32 < P6.

[0061] During the process from small waves to medium waves to relatively large waves as described above, the hydraulic load is automatically loaded step by step.

[0062] When transitioning from a larger sea state to a medium sea state, the stroke and speed of the first hydraulic cylinder 101, the second hydraulic cylinder 201, and the third hydraulic cylinder 301 will decrease. When the sum of the flow rates of the three hydraulic cylinders input into the accumulator is less than the sum of the flow rates of the first hydraulic motor 602 and the second hydraulic motor 702, the pressure of the high-pressure accumulator group 4 cannot be maintained between P5 and P6. After the third hydraulic cylinder 301 stops working, the pressure of the high-pressure accumulator group 4 will continue to decrease. When the pressure drops to P31, the third hysteresis comparator 504 starts to be in state 0. Therefore, no voltage signal is input into the second two-position three-way directional control valve 304. Under the action of the return spring, the spool returns to the right position, the D end and the E end are in a connected state, the F end is disconnected, and the oil outlet of the third hydraulic cylinder 301 returns to the low-pressure oil circuit connected to the oil tank, being in a follow-up state of ineffective work. The reduction from a 3-stage load to a 2-stage load is achieved. The pressure of the accumulator will fluctuate between P3 and P4, manifested as the continuous operation of the first hydraulic motor 602, the intermittent operation of the second hydraulic motor 702, and the non-operation of the third hydraulic motor 802. Among them, the setting of the P31 value needs to meet the condition of P3 < P31 < P5.

[0063] When transitioning from a medium sea state to a small sea state, the stroke and speed of the first hydraulic cylinder 101 and the second hydraulic cylinder 201 will continue to decrease. When the sum of the flow rates of the first hydraulic cylinder 101 and the second hydraulic cylinder 201 input into the high-pressure accumulator group 4 is less than the flow rate of the first hydraulic motor 602, the pressure of the high-pressure accumulator group 4 cannot be maintained between P3 and P4. After the second hydraulic motor 702 stops working, the pressure of the accumulator will continue to decrease. When the pressure drops to P21, at this time the hysteresis comparison controller 2 starts to be in state 0. Therefore, no voltage signal is input into the first two-position three-way directional control valve 204. Under the action of the return spring, the spool returns to the right position, the A end and the B end are in a connected state, the C end is disconnected, and the oil outlet of the second hydraulic cylinder 201 also returns to the low-pressure oil circuit connected to the oil tank, being in a follow-up state of ineffective work. The reduction from a 2-stage load to a 1-stage load is achieved. The pressure of the high-pressure accumulator group 4 will fluctuate between P1 and P2, manifested as the intermittent operation of the first hydraulic motor 602, and the non-operation of the second hydraulic motor 702 and the third hydraulic motor 802. Among them, the setting of the P21 value needs to meet the condition of P1 < P21 < P3.

[0064] During the above process from a larger sea state to a medium sea state and then to a small sea state, the hydraulic load is automatically unloaded step by step.

[0065] The above embodiment describes that each hydraulic cylinder and hydraulic motor realizes the automatic step-by-step loading of the hydraulic load in the process from small waves to medium waves to larger waves. It also describes that the hydraulic load is automatically unloaded in the process from larger waves to medium waves to small waves. Each switch can only switch to the adjacent mode, and each hysteresis comparator is provided with a lower threshold and an upper threshold, so that the hysteresis comparator will not immediately switch the reversing valve or the solenoid valve, thereby ensuring smooth mode switching and high energy conversion efficiency.

[0066] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A hydraulic load classification control system for an indirect wave energy device, characterized in that: It includes a first hydraulic cylinder group, a second hydraulic cylinder group, a third hydraulic cylinder group, a high-pressure accumulator group, a pressure detection control module, a first hydraulic generator group, a second hydraulic generator group and a third hydraulic generator group; The output end of the first hydraulic cylinder group is directly connected to the input end of the high-pressure accumulator group, and the output ends of the second hydraulic cylinder group and the third hydraulic cylinder group are respectively connected to the input end of the high-pressure accumulator group and the return oil tank through independent reversing valves. The output end of the high-pressure accumulator group is respectively connected to the first hydraulic generator group, the second hydraulic generator group and the third hydraulic generator group through independent solenoid valves. The detection end of the pressure detection control module is used to obtain the internal pressure of the high-pressure accumulator group and compare the internal pressure with a preset pressure level. According to the comparison result, the switching of the reversing valve and the solenoid valve are respectively controlled. The reversing valve is used to control the second hydraulic cylinder group and the third hydraulic cylinder group to enter / exit the effective working state, and the solenoid valve is used to control the first hydraulic generator group, the second hydraulic generator group and the third hydraulic generator group to enter / exit the power generation state; The first hydraulic cylinder group includes a first hydraulic cylinder, an input end of the first hydraulic cylinder is connected to the return oil tank through a first one-way valve, and an output end of the first hydraulic cylinder is connected to the output end of the high-pressure accumulator group through a second one-way valve. The second hydraulic cylinder group includes a second hydraulic cylinder, an input end of the second hydraulic cylinder is connected to the return oil tank through a third one-way valve, an output end of the second hydraulic cylinder is connected to the A end of the first two-position three-way reversing valve through a fourth one-way valve, a B end of the first two-position three-way reversing valve is connected to the return oil tank, and a C end of the first two-position three-way reversing valve is connected to the input end of the high-pressure accumulator group. The third hydraulic cylinder group includes a third hydraulic cylinder, an input end of the third hydraulic cylinder is connected to the return oil tank through a fifth one-way valve, an output end of the third hydraulic cylinder is connected to the D end of the second two-position three-way reversing valve through a sixth one-way valve, a E end of the second two-position three-way reversing valve is connected to the return oil tank, and a F end of the second two-position three-way reversing valve is connected to the input end of the high-pressure accumulator group. The first hydraulic generator set includes a first two-position two-way solenoid valve, a G end of the first two-position two-way solenoid valve is connected to the output end of the high-pressure accumulator group, an H end of the first two-position two-way solenoid valve is connected to the input end of the first hydraulic motor, a controlled end of the first two-position two-way solenoid valve is connected to the control end of the pressure detection control module, an output end of the first hydraulic motor is connected to the return oil tank, and an output shaft of the first hydraulic motor is connected to the input shaft of the first generator; The second hydraulic generator set includes a second two-position two-way solenoid valve, wherein the I end of the second two-position two-way solenoid valve is connected to the output end of the high-pressure accumulator group, the J end of the second two-position two-way solenoid valve is connected to the input end of the second hydraulic motor, the controlled end of the second two-position two-way solenoid valve is connected to the control end of the pressure detection control module, the output end of the second hydraulic motor is connected to the return oil tank, and the output shaft of the second hydraulic motor is connected to the input shaft of the second generator; The third hydraulic generator set includes a third two-position two-way solenoid valve, the K end of the third two-position two-way solenoid valve is connected to the output end of the high-pressure accumulator group, the L end of the third two-position two-way solenoid valve is connected to the input end of the third hydraulic motor, the controlled end of the third two-position two-way solenoid valve is connected to the control end of the pressure detection control module, the output end of the third hydraulic motor is connected to the return oil tank, and the output shaft of the third hydraulic motor is connected to the input shaft of the third generator; The pressure detection control module includes a pressure sensor, the detection end of the pressure sensor is installed at the output end of the high-pressure accumulator group, the control end of the pressure sensor is respectively connected to the input ends of the first hysteresis comparator, the second hysteresis comparator, the third hysteresis comparator, the fourth hysteresis comparator and the fifth hysteresis comparator, and the output ends of the first hysteresis comparator, the second hysteresis comparator, the third hysteresis comparator, the fourth hysteresis comparator and the fifth hysteresis comparator are respectively connected to the controlled ends of the first two-position two-way solenoid valve, the first two-position three-way reversing valve, the second two-position three-way reversing valve, the third two-position two-way solenoid valve and the second two-position two-way solenoid valve.

2. A hydraulic load grading control method for an indirect wave energy device, used in the hydraulic load grading control system of the indirect wave energy device according to claim 1, characterized in that: include: The internal pressure P of the high-pressure accumulator group is obtained in real time, and gradually increasing pressure values P1, P2, P3, P4, P5 and P6 are set, as well as gradually increasing pressure values P21, P22, P31 and P32, wherein the following pressure relationship P1 is also required to be satisfied: <P21<P3<P31<P5,P2<P22<P4<P32<P6; The control method includes a first mode, a second mode, a third mode, a fourth mode and a fifth mode, and each mode can only be transformed into an adjacent mode at a time; In the first mode, if P2≤P<P22, the second hydraulic cylinder group and the third hydraulic cylinder group are triggered to connect to the return oil tank through the corresponding reversing valve, connect the solenoid valve corresponding to the first hydraulic generator group, and disconnect the solenoid valve corresponding to the second hydraulic generator group and the third hydraulic generator group. After P2≤P<P22 is triggered, the solenoid valve corresponding to the first hydraulic generator group is allowed to be disconnected only under the condition of P≤P1; Second mode: If P22 ≤ P < P4, trigger the second hydraulic cylinder group to be connected to the input end of the high-pressure accumulator group through the corresponding reversing valve, the third hydraulic cylinder group to be connected to the oil return tank through the corresponding reversing valve, connect the solenoid valve corresponding to the first hydraulic generator set, and disconnect the solenoid valves corresponding to the second and third hydraulic generator sets. After the trigger of P22 ≤ P < P4, only when P ≤ P21, is it allowed to control the second hydraulic cylinder group to be connected to the oil return tank through the corresponding reversing valve; Third mode: If P4 ≤ P < P32, trigger the second hydraulic cylinder group to be connected to the input end of the high-pressure accumulator group through the corresponding reversing valve, the third hydraulic cylinder group to be connected to the oil return tank through the corresponding reversing valve, connect the solenoid valves corresponding to the first and second hydraulic generator sets, and disconnect the solenoid valve corresponding to the third hydraulic generator set. After the trigger of P4 ≤ P < P32, only when P ≤ P3, is it allowed to disconnect the solenoid valve corresponding to the second hydraulic generator set; Fourth mode: If P32 ≤ P < P6, trigger the second and third hydraulic cylinder groups to be connected to the input end of the high-pressure accumulator group through the corresponding reversing valves, connect the solenoid valves corresponding to the first and second hydraulic generator sets, and disconnect the solenoid valve corresponding to the third hydraulic generator set. After the trigger of P32 ≤ P < P6, only when P ≤ P31, is it allowed to control the third hydraulic cylinder group to be connected to the oil return tank through the corresponding reversing valve; Fifth mode: If P ≥ P6, trigger the reversing valves corresponding to the second and third hydraulic cylinder groups to be connected to the input end of the high-pressure accumulator group, connect the solenoid valves corresponding to the first, second, and third hydraulic generator sets. After the trigger of P ≥ P6, only when P ≤ P5, is it allowed to disconnect the solenoid valve corresponding to the third hydraulic generator set.

3. A hydraulic load grading control method for an indirect wave energy device, used in the hydraulic load grading control system of the indirect wave energy device according to claim 1, characterized in that: Including: Obtain the internal pressure P of the high-pressure accumulator group in real time through the pressure sensor, set gradually increasing pressure values P1, P2, P3, P4, P5, and P6, and gradually increasing pressure values P21, P22, P31, and P32. Among them, the following pressure relationships need to be satisfied: P1 < P21 < P3 < P31 < P5, P2 < P22 < P4 < P32 < P6; P1 and P2 are the lower and upper threshold values of the first hysteresis comparator respectively, P21 and P22 are the lower and upper threshold values of the second hysteresis comparator respectively, P31 and P32 are the lower and upper threshold values of the third hysteresis comparator respectively, P5 and P6 are the lower and upper threshold values of the fourth hysteresis comparator respectively, and P3 and P4 are the lower and upper threshold values of the fifth hysteresis comparator respectively; The control method includes a first mode, a second mode, a third mode, a fourth mode and a fifth mode, and each mode can only be transformed into an adjacent mode at a time; In the first mode, if P2 ≤ P < P22, the first hysteresis comparator is triggered to connect the G and H terminals of the first 2-position 2-way solenoid valve. After the triggering of P2 ≤ P < P22, the first hysteresis comparator is allowed to disconnect the G and H terminals of the first 2-position 2-way solenoid valve only when P ≤ P1. In the second mode, if P22 ≤ P < P4, the second hysteresis comparator is triggered to connect terminals A and C of the first two-position three-way reversing valve. After the second hysteresis comparator is triggered and disconnects terminals A and C of the first two-position three-way reversing valve only when P ≤ P21, the second hysteresis comparator is allowed to disconnect terminals A and C of the first two-position three-way reversing valve. In the third mode, if P4 ≤ P < P32, the fifth hysteresis comparator is triggered to connect terminals I and J of the second 2-position 2-way solenoid valve. After the fifth hysteresis comparator is triggered and disconnects terminals I and J of the second 2-position 2-way solenoid valve only if and only if P ≤ P3, after the fifth hysteresis comparator is triggered and disconnects terminals I and J of the second 2-position 2-way solenoid valve. In the fourth mode, if P32 ≤ P < P6, the third hysteresis comparator is triggered to connect the E and F terminals of the second two-position three-way reversing valve. After the triggering of P32 ≤ P < P6, the third hysteresis comparator is allowed to disconnect the E and F terminals of the second two-position three-way reversing valve only when P ≤ P31. In the fifth mode, if P≥P6, the fourth hysteresis comparator is triggered to control the K and L ends of the third two-position two-way solenoid valve to be connected. After P≥P6 is triggered, the fourth hysteresis comparator is allowed to disconnect the connection between the K and L ends of the third two-position two-way solenoid valve only under the condition of P≤P5.

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