Tidal current energy fixed-pitch generator set and control method thereof

Abstract

The tidal current energy fixed-pitch generator set comprises a generator, a gear box, a main blade, a controller, a main shaft and a main shaft seal, the main shaft is connected with a whole power generation transmission chain in series, and an auxiliary operation device behind the generator is connected with and disconnected from the main shaft through a clutch and comprises a main water chamber and an auxiliary water chamber which are connected with each other through a channel. A bidirectional water pump and a valve are arranged in the channel, an auxiliary shaft paddle connected with the tail shaft is arranged in the main water chamber, a liquid level meter is arranged in the main water chamber and the auxiliary water chamber, and the main water chamber is sealed with the generator through the tail shaft and the tail shaft seal. The invention further discloses a control method. The problems that a fixed-pitch unit cannot be started due to high-flow-rate incoming flow, overload occurs during operation and braking impact occurs during normal shutdown or emergency shutdown are solved or greatly improved through the auxiliary operation device, it is guaranteed that the tidal current energy fixed-pitch propeller generator set can be safely and stably connected to a grid, operate and shut down at various flow rates, and meanwhile when the unit generates power normally, the power generation efficiency is improved. And the power generation efficiency is not influenced.

Description

Technical Field

[0001] The present invention belongs to the technical field of ocean energy power generation, and in particular relates to a tidal current energy fixed pitch generator set, and a control method thereof. Background Art

[0002] Tidal energy is a type of ocean energy that uses the energy of water flow formed by the rise and fall of tides to generate electricity. It is a green and clean energy source. The flow rate and direction of the tide changes over time during the tidal period.

[0003] Tidal energy generator sets are similar to wind power generation. They control the start and stop of the units by monitoring the flow velocity and direction of the incoming flow near the installation point of the units. Currently, the capacity of the units is generally below the MW level. Considering the cost and reliability of the units, most of them adopt a fixed-pitch blade structure without a variable pitch mechanism.

[0004] The problem with the fixed-pitch blade structure is that it can only be started at a low flow rate. At this time, the blade speed can be controlled below the rated speed and is relatively stable, so the inverter can be connected to the grid normally. However, this flow rate window period is often short and easy to miss. When the inflow is too large when the unit is started, the blade rotation speed will be too fast, and the unit will accelerate too fast, causing the inverter to be unable to cut in and connect to the grid. The unit can only be forced to shut down and wait for the next tide period, which reduces the power generation time and reduces the economic benefits. If the inflow is too large and exceeds the rated flow rate during the operation of the unit, the unit will absorb too much energy and cause overload problems. The cost will increase if the maximum capacity of the unit is increased, or the commonly used speed reduction stall unloading will cause vibration problems of the unit. When the unit is shut down, the speed of the unit is first reduced by the inverter electrical brake and then withdrawn, and then the mechanical brake is used to stop the unit. During the operation, there is a delay in the connection between the inverter electrical brake and the mechanical brake, resulting in fluctuations in the speed of the unit, which will cause a certain impact on the transmission chain of the unit and affect the stability and service life of the unit. Summary of the invention

[0005] In order to solve the above-mentioned problems in the prior art, one of the objects of the present invention is to propose a tidal energy fixed-pitch generator set, which provides adjustable resistance during operation through an auxiliary operating device, and optimizes and improves the problems of starting, operating and shutting down control of the fixed-pitch tidal energy generator set.

[0006] The technical solution adopted by the present invention to solve its technical problems is: a tidal energy fixed-pitch generator set, including a generator and a main blade connected to the main shaft output end of the generator through a gear box, and also including a controller and a main shaft seal arranged between the main blade and the gear box. The main shaft is connected in series with the main blade, the gear box, and the generator to form a whole power generation transmission chain. The main blade is sealed with the gear box through the main shaft and the main shaft seal. A clutch and an auxiliary operating device are arranged in sequence behind the generator. The main shaft is connected to the stern shaft through the clutch. The auxiliary operating device includes a main water chamber and an auxiliary water chamber connected to each other through a channel. A two-way water pump and a valve connected to the controller are arranged in the channel. An auxiliary shaft propeller connected to the stern shaft at the tail of the main shaft is arranged in the main water chamber. Liquid level gauges connected to the controller are arranged in the main water chamber and the auxiliary water chamber. The main water chamber is sealed with the generator and the main shaft through the stern shaft seal and the stern shaft.

[0007] Furthermore, there is an upper opening between the main water chamber and the auxiliary water chamber, and the valve and the two-way water pump are located in the lower channel. The upper opening and the lower channel are connected to form a communicating vessel and establish pressure balance, so that the water in the main water chamber and the auxiliary water chamber can flow smoothly to each other.

[0008] Furthermore, the main water chamber is generally filled with fresh water or lubricating oil to reduce the pressure of corrosion, and the liquid level does not exceed the axis of the stern shaft to reduce the pressure of the stern shaft seal.

[0009] Furthermore, the auxiliary shaft propeller adopts a tandem double propeller with no limit on the blade type. The material can be stainless steel or nickel aluminum bronze. Composite materials are preferably used to reduce weight. According to the corresponding liquid type, commonly used low-cost metal steel materials can also be selected.

[0010] Furthermore, the controller is a PLC controller.

[0011] The second object of the present invention is to provide a control method for a tidal current energy fixed pitch generator set, the steps are: When the unit is started, it is detected that the flow rate exceeds the set upper limit flow rate of the start-up. The controller controls the clutch to connect to the auxiliary operation device, and adjusts the water level of the main water chamber through the two-way water pump. After the level gauge shows that the target water level has been reached, the controller closes the two-way water pump and the valve. After the previous steps are completed, the unit releases the brake according to the normal start-up procedure, and the main blades and the main shaft are blown by the water flow to start rotating, maintaining a stable speed so that the inverter can be successfully connected to the grid; After the unit is connected to the grid for power generation, the controller controls the clutch to disconnect the auxiliary operation device, or controls the two-way water pump to pump all or most of the water in the main water chamber into the auxiliary water chamber. The controller adjusts the liquid level height of the main water chamber by adjusting the direction and speed of the two-way water pump according to the feedback of the liquid level meter signal; When the unit is generating electricity and running, if it is detected that the flow velocity exceeds the rated flow velocity, the controller controls the clutch to connect to the auxiliary operation device, and at the same time adjusts the water level of the main water chamber through the two-way water pump. After the liquid level gauge shows that the target water level has been reached, the controller closes the two-way water pump and the valve; When the unit needs to shut down, the controller controls the clutch to connect to the auxiliary operation device, and at the same time adjusts the water level in the main water chamber through the two-way water pump. After the liquid level gauge shows that the target water level has been reached, the controller closes the two-way water pump and the valve, and then the unit executes the normal shutdown procedure. After the unit stops completely, the water is gradually pumped into the auxiliary water chamber, and finally the clutch is disconnected to cut out the auxiliary operation device.

[0012] Furthermore, when the unit needs to be shut down urgently, or the inverter cannot provide electrical braking due to a fault, the controller controls the two-way water pump and valve to open, directly raising the water level in the main water chamber to the highest level. The controller controls the clutch to connect to the auxiliary operating device and simultaneously activate the mechanical brake to prevent the unit from running away.

[0013] The beneficial effects of the present invention are: The auxiliary shaft propeller of the present invention runs in the water of the main water chamber, which can provide additional resistance when the unit is running, and provide the unit with stable starting speed, running unloading, and shutdown assistance. The liquid level of the main water chamber where the auxiliary shaft propeller is located interacts with the propeller to provide different precise resistance characteristics, which can control the speed and load of the main propeller blades. When speed and load control are not required, it is cut out without affecting the rotation of the main propeller blades. According to the flow rate and different working conditions, the controller controls the two-way water pump and valve to adjust the water level of the main water chamber according to the feedback of the liquid level meter data, and matches the resistance, so that the unit can operate and shut down stably and safely within any flow range.

[0014] The present invention solves or greatly improves the problems of fixed-pitch units failing to start at high flow rates, overloading during operation, and brake impact during shutdown through an auxiliary operating device, while ensuring that the tidal energy fixed-pitch propeller generator set can be safely and stably connected to the grid, generate electricity, and shut down at various flow rates. At the same time, when the unit is generating electricity normally, it can be cut out without affecting the power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall structural diagram of the present invention; Figure 2 It is a structural schematic diagram of the auxiliary operation device of the present invention.

[0016] The reference numerals of the figures are: 1—main propeller blade, 2—main shaft seal, 3—gear box, 4—generator, 5—auxiliary operating device, 51—auxiliary shaft propeller, 52—main water chamber, 53—auxiliary water chamber, 54—liquid level gauge, 55—channel, 56—bidirectional water pump, 57—valve, 58—stern shaft, 6—stern shaft seal, 7—clutch, 8—main shaft. DETAILED DESCRIPTION

[0017] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. For example, although the various components in the accompanying drawings are drawn in specific proportions, these proportional relationships are only exemplary, and those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0018] It should be noted that, in the description of the present invention, terms such as "center", "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed or operate in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0019] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be a connection between two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] According to one embodiment of the present invention, Figure 1 As shown, a tidal energy fixed pitch generator set disclosed in the present invention mainly includes a main blade 1, a main shaft seal 2, a gear box 3, a generator 4, a stern shaft seal 6, a clutch 7, a controller and a main shaft 8, and also includes an auxiliary operation device 5. The unit works as a whole underwater, and the sealing of the main blade 1 and the gear box 3 is realized by the main shaft seal 2. The auxiliary operation device 5 arranged after the generator 4 is connected and disconnected with the output shaft of the main blade 1, that is, the main shaft 8, through the clutch 7, and provides rotation resistance for the main blade 1 to control the speed and load or cut out without affecting the rotation of the main blade 1. The auxiliary operation device 5 and the generator 4 are sealed by the stern shaft seal 6. The main shaft 8 is connected in series with the entire power generation transmission chain, and the main shaft 8 is connected to the stern shaft 58 through the clutch 7.

[0021] Reference Figure 2As shown, the auxiliary operation device 5 is composed of an auxiliary shaft propeller 51, a main water chamber 52, an auxiliary water chamber 53, a liquid level gauge 54, a channel 55, a two-way water pump 56, a valve 57 and a stern shaft 58. The main water chamber 52 and the auxiliary water chamber 53 are connected at the upper and lower parts. A valve 57 and a two-way water pump 56 connected to the controller are arranged in the lower channel 55. The upper openings are connected to form a communicating vessel and establish pressure balance. The water in the main water chamber 52 and the auxiliary water chamber 53 can flow smoothly to each other. Fresh water or lubricating oil is generally used in the main water chamber 52 to reduce the pressure of corrosion. The water level is generally set below the axis of the stern shaft 58, which can reduce the pressure of the stern shaft seal 6. The auxiliary shaft propeller 51 can be made of common low-cost metal materials such as stainless steel or nickel-aluminum bronze to reduce the pressure of corrosion. Composite materials are preferably used to reduce weight. According to the corresponding liquid type, common low-cost metal steel materials can also be selected. The blades of the auxiliary shaft propeller 51 can be tandem double propellers, which can reduce the diameter of the propeller.

[0022] The auxiliary shaft propeller 51 in the main water chamber 52 is connected to the stern shaft 58, and the liquid level gauges 54 in the main water chamber 52 and the auxiliary water chamber 53 are connected to the controller. The main water chamber 52 forms a seal with the generator 4 through the stern shaft seal 6 and the stern shaft 58. The other static joint surfaces of the unit are sealed by O-rings or gaskets and fixed with bolts to prevent mutual leakage. The auxiliary shaft propeller 51 runs in the water of the main water chamber 52, which can provide additional resistance when the unit is started, and provide the unit with stable starting speed, operation unloading, and shutdown assistance. The liquid level of the main water chamber 52 interacts with the auxiliary shaft propeller 51 to provide different resistance characteristics, thereby providing rotational resistance for the main blade 1 to control the speed and load or cut out without affecting the rotation of the main blade 1. According to the incoming flow velocity and different working conditions, the controller controls the two-way water pump 56 and the valve 57 to adjust the water level of the main water chamber 52 according to the data of the liquid level gauge 54, and matches the resistance, so that the unit can operate and shut down stably and safely within any incoming flow range.

[0023] After the unit is connected to the grid, the controller controls the clutch 7 to disconnect the auxiliary operation device 5, or controls the two-way water pump 56 to pump all or most of the water in the main water chamber 52 into the auxiliary water chamber 53 through the two-way water pump 56, which can cut off the influence of the auxiliary operation device 5 when the unit is generating electricity normally, and will not cause efficiency loss. The heat generated by the auxiliary shaft propeller 51 during rotation can be conducted to the seawater through the outer shells of the main water chamber 52 and the auxiliary water chamber 53, without the need for an additional cooling system. The controller freely adjusts the liquid level of the main water chamber 52 as needed by adjusting the direction and speed of the two-way water pump 56 according to the signal feedback of the liquid level meter 54, thereby accurately controlling the size of the rotation resistance of the auxiliary shaft propeller 51. When the clutch 7 fails and cannot be disengaged, the water in the main water chamber 52 can be emptied until the auxiliary shaft propeller 51 is exposed to the air, which can minimize the efficiency loss caused by the auxiliary shaft propeller 51 during normal power generation of the unit.

[0024] When the unit is started, when it is detected that the flow rate exceeds the set upper limit flow rate, the controller controls the clutch 7 to connect to the auxiliary operation device 5, and at the same time adjusts the water level of the main water chamber 52 through the two-way water pump 56. After the liquid level meter 54 shows that the target water level has been reached, the controller closes the two-way water pump 56 and the valve 57. After the previous steps are completed, the unit releases the brake according to the normal procedure, and the main blade 1 together with the main shaft 8 is blown by the water flow to start rotating. Due to the corresponding resistance provided by the auxiliary operation device 5, the unit can maintain a stable speed and thus be smoothly connected to the grid through the inverter.

[0025] When the unit is running, if it is detected that the flow velocity exceeds the rated flow velocity, the controller controls the clutch 7 to connect to the auxiliary operation device 5, and at the same time, the controller adjusts the water level of the main water chamber 52 through the two-way water pump 56. After the liquid level meter 54 shows that the target water level has been reached, the controller closes the two-way water pump 56 and the valve 57. During the whole process, the unit generates electricity normally, and no other operations are required except the auxiliary operation device 5. If the incoming flow velocity increases further, the water level of the main water chamber 52 can continue to increase. After the subsequent incoming flow velocity is reduced to the rated flow velocity, the water is gradually pumped out to the auxiliary water chamber 52, and finally the controller disconnects the clutch 7 to cut out the auxiliary operation device 5.

[0026] After the unit is connected to the grid for power generation, the auxiliary operation device 5 is no longer needed to provide resistance. The controller controls the clutch 7 to disconnect the auxiliary operation device 5, or controls the two-way water pump 56 to pump all or most of the water in the main water chamber 52 into the auxiliary water chamber 53 through the two-way water pump 56. This can eliminate the influence of the auxiliary operation device 5 on the normal power generation of the unit without causing any loss in efficiency. The heat generated by the auxiliary shaft propeller 51 during rotation can be conducted to the seawater through the outer shells of the main water chamber 52 and the auxiliary water chamber 53 without the need for an additional cooling system. Based on the signal feedback from the liquid level meter 54, the controller can freely adjust the liquid level of the main water chamber 52 as needed by adjusting the direction and speed of the two-way water pump 56, thereby accurately controlling the size of the rotation resistance of the auxiliary shaft propeller 51. When the clutch 7 fails and cannot be disengaged, the water in the main water chamber 52 can be emptied until the auxiliary shaft propeller 51 is exposed to the air, which can minimize the efficiency loss caused by the auxiliary shaft propeller 51 during normal power generation of the unit. When the unit is generating electricity and running, if it is detected that the flow velocity exceeds the rated flow velocity, the controller controls the clutch 7 to connect to the auxiliary operation device 5. At the same time, the controller adjusts the water level of the main water chamber 52 through the two-way water pump 56. After the level gauge 54 shows that the target water level has been reached, the controller closes the two-way water pump 56 and the valve 57. During the whole process, the unit generates electricity normally, and the excess energy is offset by the resistance provided by the auxiliary operation device 5. If the incoming flow velocity increases further, the water level of the main water chamber 52 can continue to increase to increase the resistance. After the subsequent incoming flow velocity is reduced to the rated flow velocity, the water is gradually pumped into the auxiliary water chamber 53, and finally the controller disconnects the clutch 7 to cut out the auxiliary operation device 5.

[0027] When the unit needs to be shut down, the controller controls the clutch 7 to connect to the auxiliary operation device 5, and adjusts the water level of the main water chamber 52 through the two-way water pump 56. After the liquid level meter 54 shows that the target water level has been reached, the controller closes the two-way water pump 56 and the valve 57. At this time, the unit executes the normal shutdown procedure, firstly, the unit speed is pulled down as much as possible through the frequency converter and then withdrawn, and then the mechanical brake is put into use. Due to the resistance provided by the auxiliary operation device 5, the speed of the unit will not rise when the unit brakes, and the impact is small. After the unit stops completely, the water is gradually pumped out to the auxiliary water chamber 53, and finally the clutch 7 is disconnected to cut out the auxiliary operation device 5.

[0028] When the unit needs emergency shutdown, or the inverter cannot provide electrical braking due to a fault, the controller directly opens the valve 57 and the two-way water pump 56, directly raising the water level in the main water chamber 52 to the highest level, and the clutch 7 is connected to the auxiliary operation device 5 and the mechanical brake is applied at the same time. At this time, the auxiliary operation device 5 can provide the maximum resistance to prevent the unit from running away.

[0029] In a further implementation case, when it is necessary to increase the response speed of the auxiliary operating device 5, the clutch 7 may not be disconnected at all, and the resistance may be controlled only by adjusting the water level. When the unit does not need to provide resistance during normal operation, the water level in the main water chamber 52 may be lowered to a level that does not touch the auxiliary shaft propeller 51, and the efficiency loss can be reduced to a very low level.

[0030] Through the application of the above patents, it is ensured that the tidal fixed-pitch propeller generator set can be safely and stably connected to the grid, generate electricity, and shut down under various flow rates. At the same time, when the unit is generating electricity normally, it can be cut out without affecting the power generation efficiency. When it is shut down normally or due to a fault, the impact vibration caused by braking can be greatly reduced.

[0031] The above embodiments are only illustrative of the principles and effects of the present invention, as well as some embodiments of its application. For those skilled in the art, several modifications and improvements may be made without departing from the creative concept of the present invention, and all of these belong to the protection scope of the present invention.

Claims

1. A tidal current energy fixed pitch generator set, comprising a generator (4) and a main blade (1) connected to an output end of a main shaft (8) of the generator (4) via a gear box (3), and further comprising a controller and a main shaft seal (2) arranged between the main blade (1) and the gear box (3), characterized in that: A clutch (7) and an auxiliary operating device (5) are sequentially arranged behind the generator (4); the main shaft (8) is connected to the stern shaft (58) via the clutch (7); the auxiliary operating device (5) comprises a main water chamber (52) and an auxiliary water chamber (53) connected to each other via a channel (55); a two-way water pump (56) and a valve (57) connected to a controller are arranged in the channel (55); an auxiliary shaft propeller (51) connected to the stern shaft (58) is arranged in the main water chamber (52); a liquid level gauge (54) connected to the controller is arranged in the main water chamber (52) and the auxiliary water chamber (53); the main water chamber (52) forms a seal with the generator (4) via a stern shaft seal (6) and the stern shaft (58).

2. A tidal current energy fixed pitch generator set according to claim 1, characterized in that: An upper opening is provided between the main water chamber (52) and the auxiliary water chamber (53), and the bidirectional water pump (56) and the valve (57) are located in the lower channel (55).

3. A tidal current fixed pitch generator set according to claim 2, characterized in that: The main water chamber (52) is filled with fresh water or lubricating oil, and the height of the liquid level does not exceed the axis of the stern shaft (58).

4. A tidal current energy fixed pitch generator set according to claim 3, characterized in that: The auxiliary shaft propeller (51) is a tandem double propeller.

5. A tidal current energy fixed pitch generator set according to claim 3, characterized in that: The auxiliary shaft propeller (51) is made of stainless steel or nickel-aluminum bronze or composite material blades.

6. A tidal current energy fixed pitch generator set according to any one of claims 1 to 5, characterized in that: The controller is a PLC controller.

7. A control method for a tidal current energy fixed pitch generator set as claimed in claim 1, characterized in that: The steps are: When the unit is started, it is detected that the flow rate exceeds the set upper limit, and the controller controls the clutch (7) to connect the auxiliary operation device (5), and at the same time adjusts the water level of the main water chamber (52) through the two-way water pump (56). After the liquid level meter (54) shows that the target water level has been reached, the controller turns off the two-way water pump (56) and the valve (57), and then releases the brake, so that the main blade (1) and the main shaft (8) are blown by the water flow and start to rotate; After the unit is connected to the grid for power generation, the controller controls the clutch (7) to disconnect the auxiliary operation device (5), or controls the bidirectional water pump (56) to pump all or most of the water in the main water chamber (52) into the auxiliary water chamber (53), and the controller adjusts the liquid level of the main water chamber (52) by adjusting the direction and speed of the bidirectional water pump (56) according to the signal feedback from the liquid level meter (54); When the unit is generating electricity and it is detected that the flow velocity exceeds the rated flow velocity, the controller controls the clutch (7) to connect the auxiliary operation device (5), and at the same time adjusts the water level of the main water chamber (52) through the two-way water pump (56). After the liquid level meter (54) shows that the target water level has been reached, the controller closes the two-way water pump (56) and the valve (57); When the unit needs to be shut down, the controller controls the clutch (7) to connect to the auxiliary operation device (5), and at the same time adjusts the water level of the main water chamber (52) through the two-way water pump (56). After the liquid level meter (54) shows that the target water level has been reached, the controller closes the two-way water pump (56) and the valve (57), and then the unit is shut down. After the unit is completely stopped, the water is gradually pumped out to the auxiliary water chamber (53), and finally the clutch (7) is disconnected to cut out the auxiliary operation device (5).

8. The control method of a tidal current energy fixed pitch generator set according to claim 7, characterized in that: When the unit needs to be shut down urgently, the controller controls the bidirectional water pump (56) and the valve (57) to open, directly raising the water level in the main water chamber (52) to the highest level, and the controller controls the clutch (7) to connect to the auxiliary operation device (5) and activate the mechanical brake at the same time.

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